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  • 1.
    AlSalhi, M S.
    et al.
    King Saud University, Saudi Arabia .
    Atif, M
    King Saud University, Saudi Arabia; National Institute of Laser and Optronics, Nilore, Islamabad, Pakistan.
    Ansari, A A.
    King Saud University, Saudi Arabia .
    Khun, Kimleang
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Hussain Ibupoto, Zafar
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology. King Saud University, Riyadh, Saudi Arabia.
    Growth and characterization of ZnO nanowires for optical applications2013In: Laser physics, ISSN 1054-660X, E-ISSN 1555-6611, Vol. 23, no 6, article id 065602Article in journal (Refereed)
    Abstract [en]

    In the present work, cerium oxide CeO2 nanoparticles were synthesized by the sol-gel method and used for the growth of ZnO nanorods. The synthesized nanoparticles were studied by x-ray diffraction (XRD) and Raman spectroscopic techniques. Furthermore, these nanoparticles were used as the seed layer for the growth of ZnO nanorods by following the hydrothermal growth method. The structural study of ZnO nanorods was carried out by means of field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and XRD techniques. This study demonstrated that the grown ZnO nanorods are well aligned, uniform, of good crystal quality and have diameters of less than 200 nm. Energy dispersive x-ray (EDX) analysis revealed that the ZnO nanorods are composed only of zinc, cerium as the seed atom, and oxygen atoms, with no other impurities in the grown nanorods. Moreover, a photoluminescence (PL) approach was applied for the optical characterization, and it was observed that the near-band-edge (NBE) emission was the same as that of the zinc acetate seed layer, however the green and orange/red emission peaks were slightly raised due to possibly higher levels of defects in the cerium oxide seeded ZnO nanorods. This study provides an alternative approach for the controlled synthesis of ZnO nanorods using cerium oxide nanoparticles as the seed nucleation layer, improving both the morphology of the nanorods and the performance of devices based upon them.

  • 2.
    Amloy, Supaluck
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology. Department of Physics, Faculty of Science, Thaksin University, 93110 Phattalung, Thailand .
    Yu, K. H.
    Linköping University, Department of Physics, Chemistry and Biology.
    Karlsson, K Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Farivar, R.
    Applied Semiconductor Physics, Department of Microtechnology and Nanoscience, Chalmers University of Technology, S‐41296 Göteborg, Sweden.
    Andersson, T. G.
    Applied Semiconductor Physics, Department of Microtechnology and Nanoscience, Chalmers University of Technology, S‐41296 Göteborg, Sweden.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Polarized Emission from Single GaN Quantum Dots Grown by Molecular Beam Epitaxy2011Conference paper (Other academic)
    Abstract [en]

    Polarization resolved microphotoluminescence measurements of single MBE‐grown GaN/Al(Ga)N quantum dots (QDs) have been performed. The exciton and biexciton peaks with full width at half maximum as narrow as <500 μeV  were observed. Interestingly, there exist both positive and negative binding energies of the biexciton, explained in term of different sizes of the measured dots, resulting in different built‐in electric field. Moreover, a strongly linearly polarized emission is observed for the investigated dots with a degree of linear polarization of about 0.9, interpreted as the valence‐band mixing induced by in‐plane anisotropy due to strain and/or QD shape.

  • 3.
    Antonsson, Johan
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Eriksson, Ola
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Radio frequency electrode system for optical lesion size estimation in functional neurosurgery2005In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 10, no 3, p. 1-6Article in journal (Refereed)
    Abstract [en]

    Radiofrequency(RF) lesioning in the human brain is one possible surgicaltherapy for severe pain as well as movement disorders. Oneobstacle for a safer lesioning procedure is the lack ofsize monitoring. The aim of this study was to investigateif changes in laser Doppler or intensity signals could beused as markers for size estimation during experimental RF lesioning.A 2 mm in diameter monopolar RF electrode was equippedwith optical fibers and connected to a digital laser Dopplersystem. The optical RF electrode's performance was equal to astandard RF electrode with the same dimensions. An albumin solutionwith scatterers was used to evaluate the intensity and laserDoppler signal changes during lesioning at 70, 80, and 90 °C.Significant signal changes were found for these three different clotsizes, represented by the temperatures (p<0.05,  n=10). The volume, width, andlength of the created coagulations were correlated to the intensitysignal changes (r=0.88, n=30, p<0.0001) and to the perfusion signalchanges (r=0.81, n=30, p<0.0001). Both static and Doppler-shifted light canbe used to follow the lesioning procedure as well asbeing used for lesion size estimation during experimental RF lesioning.

  • 4.
    Armakavicius, Nerijus
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Study of novel electronic materials by mid-infrared and terahertz optical Hall effect2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Development of silicon based electronics have revolutionized our every day life during the last three decades. Nowadays Si based devices operate close to their theoretical limits that is becoming a bottleneck for further progress. In particular, for the growing field of high frequency and high power electronics, Si cannot offer the required properties. Development of materials capable of providing high current densities, carrier mobilities and high breakdown fields is crucial for a progress in state of the art electronics.

    Epitaxial graphene grown on semi-insulating silicon carbide substrates has a high potential to be integrated in the current planar device technologies. High electron mobilities and sheet carrier densities make graphene extremely attractive for high frequency analog applications. One of the remaining challenges is the interaction of epitaxial graphene with the substrate. Typically, much lower free charge carrier mobilities, compared to free standing graphene, and doping, due to charge transfer from the substrate, is reported. Thus, a good understanding of the intrinsic free charge carriers properties and the factors affecting them is very important for further development of epitaxial graphene.

    III-group nitrides have been extensively studied and already have proven their high efficiency as light sources for short wavelengths. High carrier mobilities and breakdown electric fields were demonstrated for III-group nitrides, making them attractive for high frequency and high power applications. Currently, In-rich InGaN alloys and AlGaN/GaN high electron mobility structures are of high interest for the research community due to open fundamental questions.

    Electrical characterization techniques, commonly used for the determination of free charge carrier properties, require good ohmic and Schottky contacts, which in certain cases can be difficult to achieve. Access to electrical properties of buried conductive channels in multilayered structures requires modification of samples and good knowledge of the electrical properties of all electrical contact within the structure. Moreover, the use of electrical contacts to electrically characterize two-dimensional electronic materials, such as graphene, can alter their intrinsic properties. Furthermore, the determination of effective mass parameters commonly employs cyclotron resonance and Shubnikov-de Haas oscillations measurements, which require long scattering times of free charge carriers, high magnetic fields and low temperatures.

    The optical Hall effect is an external magnetic field induced optical anisotropy in  conductive layers due to the motion of the free charge carriers under the influence of the Lorentz force, and is equivalent to the electrical Hall effect at optical frequencies. The optical Hall effect can be measured by generalized ellipsometry and provides a powerful method for the determination of free charge carrier properties in a non-destructive and contactless manner. In principle, a single optical Hall effect measurement can provide quantitative information about free charge carrier types, concentrations, mobilities and effective mass parameters at temperatures ranging from few kelvins to room temperature and above. Further, it was demonstrated that for transparent samples, a backside cavity can be employed to enhance the optical Hall effect.

    Measurement of the optical Hall effect by generalized ellipsometry is an indirect technique requiring subsequent data analysis. Parameterized optical models are fitted to match experimentally measured ellipsometric data by varying physically significant parameters. Analysis of the optical response of samples, containing free charge carriers, employing optical models based on the classical Drude model, which is augmented with an external magnetic field contribution, provide access to the free charge carrier properties.

    The main research results of the graduate studies presented in this licentiate thesis are summarized in the five scientific papers.

    Paper I. Description of the custom-built terahertz frequency-domain spectroscopic ellipsometer at Linköping University. The terahertz ellipsometer capabilities are demonstrated by an accurate determination of the isotropic and anisotropic refractive indices of silicon and m-plane sapphire, respectively. Further, terahertz optical Hall effect measurements of an AlGaN/GaN high electron mobility structures were employed to extract the two-dimensional electron gas sheet density, mobility and effective mass parameters. Last, in-situ optical Hall effect measurement on epitaxial graphene in a gas cell with controllable environment, were used to study the effects of environmental doping on the mobility and carrier concentration.

    Paper II. Presents terahertz cavity-enhanced optical Hall measurements of the monolayer and multilayer epitaxial graphene on semi-insulating 4H-SiC (0001) substrates. The data analysis revealed p-type doping for monolayer graphene with a carrier density in the low 1012 cm−2 range and a carrier mobility of 1550 cm2/V·s. For the multilayer epitaxial graphene, n-type doping with a carrier density in the low 1013 cm−2 range, a mobility of 470 cm2/V·s and an effective mass of (0.14 ± 0.03) m0 were extracted. The measurements demonstrate that cavity-enhanced optical Hall effect measurements can be applied to study electronic properties of two-dimensional materials.

    Paper III. Terahertz cavity-enhanced optical Hall effect measurements are employed to study anisotropic transport in as-grown monolayer, quasi free-standing monolayer and quasi free-standing bilayer epitaxial graphene on semi-insulating 4H-SiC (0001) substrates. The data analysis revealed a strong anisotropy in the carrier mobilities of the quasi freestanding bilayer graphene. The anisotropy is demonstrated to be induced by carriers scattering at the step edges of the SiC, by showing that the mobility is higher along the step than across them. The scattering mechanism is discussed based on the results of the optical Hall effect, low-energy electron microscopy, low-energy electron diffraction and Raman measurements.

    Paper IV. Mid-infrared spectroscopic ellipsometry and mid-infrared optical Hall effect measurements are employed to determine the electron effective mass in an In0.33Ga0.67N epitaxial layer. The data analysis reveals slightly anisotropic effective mass and carrier mobility parameters together with the optical phonon frequencies and broadenings.

    Paper V. Terahertz cavity-enhanced optical Hall measurements are employed to study the free charge carrier properties in a set of AlGaN/GaN high electron mobility structures with modified interfaces. The results show that the interface structure has a significant effect on the free charge carrier mobility and that the sample with a sharp interface between an AlGaN barrier and a GaN buffer layers exhibits a record mobility of 2332±73 cm2/V·s. The determined effective mass parameters showed an increase compared to the GaN value, that is attributed the the penetration of the electron wavefunction into the AlGaN barrier layer.

    List of papers
    1. Cavity-enhanced optical Hall effect in epitaxial graphene detected at terahertz frequencies
    Open this publication in new window or tab >>Cavity-enhanced optical Hall effect in epitaxial graphene detected at terahertz frequencies
    Show others...
    2017 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 421, p. 357-360Article in journal (Refereed) Published
    Abstract [en]

    Cavity-enhanced optical Hall effect at terahertz (THz) frequencies is employed to determine the free charge carrier properties in epitaxial graphene (EG) with different number of layers grown by high-temperature sublimation on 4H-SiC(0001). We find that one monolayer (ML) EG possesses p-type conductivity with a free hole concentration in the low 1012 cmᅵᅵᅵ2 range and a free hole mobility parameter as high as 1550 cm2/Vs. We also find that 6 ML EG shows n-type doping behavior with a much lower free electron mobility parameter of 470 cm2/Vs and an order of magnitude higher free electron density in the low 1013 cmᅵᅵᅵ2 range. The observed differences are discussed. The cavity-enhanced THz optical Hall effect is demonstrated to be an excellent tool for contactless access to the type of free charge carriers and their properties in two-dimensional materials such as EG.

    Place, publisher, year, edition, pages
    Elsevier, 2017
    Keywords
    THz optical Hall effect, Epitaxial graphene, Free charge carrier properties
    National Category
    Physical Sciences Condensed Matter Physics Atom and Molecular Physics and Optics Ceramics
    Identifiers
    urn:nbn:se:liu:diva-132407 (URN)10.1016/j.apsusc.2016.10.023 (DOI)000408756700015 ()
    Note

    Funding agencies: Swedish Research Council (VR) [2013-5580]; Swedish Governmental Agency for Innovation Systems (VINNOVA) under the VINNMER international qualification program [2011-03486, 2014-04712]; Swedish foundation for strategic research (SSF) [FFL12-0181, RIF14-055]

    Available from: 2016-11-09 Created: 2016-11-09 Last updated: 2018-01-12Bibliographically approved
    2. Properties of two-dimensional electron gas in AlGaN/GaN HEMT structures determined by cavity-enhanced THz optical Hall effect
    Open this publication in new window or tab >>Properties of two-dimensional electron gas in AlGaN/GaN HEMT structures determined by cavity-enhanced THz optical Hall effect
    Show others...
    2016 (English)In: Physica Status Solidi C-Current Topics in Solid State Physics, Vol 13 No 5-6, Wiley-VCH Verlagsgesellschaft, 2016, Vol. 13, no 5-6, p. 369-373Conference paper, Published paper (Refereed)
    Abstract [en]

    In this work we employ terahertz (THz) ellipsometry to determine two-dimensional electron gas (2DEG) density, mobility and effective mass in AlGaN/GaN high electron mobility transistor structures grown on 4H-SiC substrates. The effect of the GaN interface exposure to low-flow-rate trimethylaluminum (TMA) on the 2DEG properties is studied. The 2DEG effective mass and sheet density are determined tobe in the range of 0.30-0.32m0 and 4.3-5.5×1012 cm–2, respectively. The 2DEG effective mass parameters are found to be higher than the bulk effective mass of GaN, which is discussed in view of 2DEG confinement. It is shown that exposure to TMA flow improves the 2DEG mobility from 2000 cm2/Vs to values above 2200 cm2/Vs. A record mobility of 2332±61 cm2/Vs is determined for the sample with GaN interface exposed to TMA for 30 s. This improvement in mobility is suggested to be due to AlGaN/GaN interface sharpening causing the reduction of interface roughness scattering of electrons in the 2DEG.

    Place, publisher, year, edition, pages
    Wiley-VCH Verlagsgesellschaft, 2016
    Series
    Physica Status Solidi C-Current Topics in Solid State Physics, ISSN 1862-6351
    Keywords
    AlGaN/GaN HEMTs, THz ellipsometry, 2DEG properties, THz optical Hall effect
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-133135 (URN)10.1002/pssc.201510214 (DOI)000387957200045 ()
    Conference
    11th International Conference on Nitride Semiconductors (ICNS), Beijing, China, August 30-September 4. 2015
    Available from: 2016-12-12 Created: 2016-12-09 Last updated: 2017-10-23Bibliographically approved
  • 5.
    Armakavicius, Nerijus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Bouhafs, Chamseddine
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Stanishev, Vallery
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Kühne, Philipp
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Knight, Sean
    Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, USA.
    Hofmann, Tino
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, USA / Department of Physics and Optical Science, University of North Carolina at Charlotte, USA.
    Schubert, Mathias
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, USA.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Cavity-enhanced optical Hall effect in epitaxial graphene detected at terahertz frequencies2017In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 421, p. 357-360Article in journal (Refereed)
    Abstract [en]

    Cavity-enhanced optical Hall effect at terahertz (THz) frequencies is employed to determine the free charge carrier properties in epitaxial graphene (EG) with different number of layers grown by high-temperature sublimation on 4H-SiC(0001). We find that one monolayer (ML) EG possesses p-type conductivity with a free hole concentration in the low 1012 cmᅵᅵᅵ2 range and a free hole mobility parameter as high as 1550 cm2/Vs. We also find that 6 ML EG shows n-type doping behavior with a much lower free electron mobility parameter of 470 cm2/Vs and an order of magnitude higher free electron density in the low 1013 cmᅵᅵᅵ2 range. The observed differences are discussed. The cavity-enhanced THz optical Hall effect is demonstrated to be an excellent tool for contactless access to the type of free charge carriers and their properties in two-dimensional materials such as EG.

  • 6.
    Aronsson, Christopher
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Tunable and modular assembly of polypeptides and polypeptide-hybrid biomaterials2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Biomaterials are materials that are specifically designed to be in contact with biological systems and have for a long time been used in medicine. Examples of biomaterials range from sophisticated prostheses used for replacing outworn body parts to ordinary contact lenses. Currently it is possible to create biomaterials that can e.g. specifically interact with cells or respond to certain stimuli. Peptides, the shorter version of proteins, are excellent molecules for fabrication of such biomaterials. By following and developing design rules it is possible to obtain peptides that can self-assemble into well-defined nanostructures and biomaterials.

    The aim of this thesis is to create ”smart” and tunable biomaterials by molecular self-assembly using dimerizing –helical polypeptides. Two different, but structurally related, polypeptide-systems have been used in this thesis. The EKIV-polypeptide system was developed in this thesis and consists of four 28-residue polypeptides that can be mixed-and-matched to self-assemble into four different coiled coil heterodimers. The dissociation constant of the different heterodimers range from μM to < nM. Due to the large difference in affinities, the polypeptides are prone to thermodynamic social self-sorting. The JR-polypeptide system, on the other hand, consists of several 42-residue de novo designed helix-loop-helix polypeptides that can dimerize into four-helix bundles. In this work, primarily the glutamic acid-rich polypeptide JR2E has been explored as a component in supramolecular materials. Dimerization was induced by exposing the polypeptide to either Zn2+, acidic conditions or the complementary polypeptide JR2K.

    By conjugating JR2E to hyaluronic acid and the EKIV-polypeptides to star-shaped poly(ethylene glycol), respectively, highly tunable hydrogels that can be self-assembled in a modular fashion have been created. In addition, self-assembly of spherical superstructures has been investigated and were obtained by linking two thiol-modified JR2E polypeptides via a disulfide bridge in the loop region. ŒThe thesis also demonstrates that the polypeptides and the polypeptide-hybrids can be used for encapsulation and release of molecules and nanoparticles. In addition, some of the hydrogels have been explored for 3D cell culture. By using supramolecular interactions combined with bio-orthogonal covalent crosslinking reactions, hydrogels were obtained that enabled facile encapsulation of cells that retained high viability.

    The results of the work presented in this thesis show that dimerizing α–helical polypeptides can be used to create modular biomaterials with properties that can be tuned by specific molecular interactions. The modularity and the tunable properties of these smart biomaterials are conceptually very interesting andmake them useful in many emerging biomedical applications, such as 3D cell culture, cell therapy, and drug delivery

    .

    List of papers
    1. Self-sorting heterodimeric coiled coil peptides with defined and tuneable self-assembly properties
    Open this publication in new window or tab >>Self-sorting heterodimeric coiled coil peptides with defined and tuneable self-assembly properties
    Show others...
    2015 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, no 14063Article in journal (Refereed) Published
    Abstract [en]

    Coiled coils with defined assembly properties and dissociation constants are highly attractive components in synthetic biology and for fabrication of peptide-based hybrid nanomaterials and nanostructures. Complex assemblies based on multiple different peptides typically require orthogonal peptides obtained by negative design. Negative design does not necessarily exclude formation of undesired species and may eventually compromise the stability of the desired coiled coils. This work describe a set of four promiscuous 28-residue de novo designed peptides that heterodimerize and fold into parallel coiled coils. The peptides are non-orthogonal and can form four different heterodimers albeit with large differences in affinities. The peptides display dissociation constants for dimerization spanning from the micromolar to the picomolar range. The significant differences in affinities for dimerization make the peptides prone to thermodynamic social self-sorting as shown by thermal unfolding and fluorescence experiments, and confirmed by simulations. The peptides self-sort with high fidelity to form the two coiled coils with the highest and lowest affinities for heterodimerization. The possibility to exploit self-sorting of mutually complementary peptides could hence be a viable approach to guide the assembly of higher order architectures and a powerful strategy for fabrication of dynamic and tuneable nanostructured materials.

    Place, publisher, year, edition, pages
    NATURE PUBLISHING GROUP, 2015
    National Category
    Physical Sciences Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:liu:diva-121739 (URN)10.1038/srep14063 (DOI)000361177400001 ()26370878 (PubMedID)
    Note

    Funding Agencies|Swedish Research Council (VR); Swedish Foundation for Strategic Research (SSF)

    Available from: 2015-10-06 Created: 2015-10-05 Last updated: 2017-12-01
    2. Tailoring Supramolecular Peptide-Poly(ethylene glycol) Hydrogels by Coiled Coil Self-Assembly and Self-Sorting
    Open this publication in new window or tab >>Tailoring Supramolecular Peptide-Poly(ethylene glycol) Hydrogels by Coiled Coil Self-Assembly and Self-Sorting
    2016 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 17, no 6, p. 2260-2267Article in journal (Refereed) Published
    Abstract [en]

    Physical hydrogels are extensively used in a wide range of biomedical applications. However, different applications require hydrogels with different mechanical and structural properties. Tailoring these properties demands exquisite control over the supramolecular peptides with different affinities for dimerization. Four different mechanical properties of hydrogels using de novo designed coiled coil interactions involved. Here we show that it is possible to control the nonorthogonal peptides, designed to fold into four different coiled coil heterodimers with dissociation constants spanning from mu M to pM, were conjugated to star-shaped 4-arm poly(ethylene glycol) (PEG). The different PEG-coiled coil conjugates self-assemble as a result of peptide heterodimerization. Different combinations of PEG peptide conjugates assemble into PEG peptide networks and hydrogels with distinctly different thermal stabilities, supramolecular, and rheological properties, reflecting the peptide dimer affinities. We also demonstrate that it is possible to rationally modulate the self-assembly process by means of thermodynamic self-sorting by sequential additions of nonpegylated peptides. The specific interactions involved in peptide dimerization thus provides means for programmable and reversible self-assembly of hydrogels with precise control over rheological properties, which can significantly facilitate optimization of their overall performance and adaption to different processing requirements and applications.

    Place, publisher, year, edition, pages
    AMER CHEMICAL SOC, 2016
    National Category
    Polymer Chemistry
    Identifiers
    urn:nbn:se:liu:diva-130135 (URN)10.1021/acs.biomac.6b00528 (DOI)000377924800038 ()27219681 (PubMedID)
    Note

    Funding Agencies|Swedish Research Council [621-2011-4319]; Swedish Foundation for Strategic Research [ICA10-0002]; Linkoping University; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009 00971]

    Available from: 2016-07-12 Created: 2016-07-11 Last updated: 2017-11-28
    3. Zinc-Triggered Hierarchical Self-Assembly of Fibrous Helix-Loop-Helix Peptide Superstructures for Controlled Encapsulation and Release
    Open this publication in new window or tab >>Zinc-Triggered Hierarchical Self-Assembly of Fibrous Helix-Loop-Helix Peptide Superstructures for Controlled Encapsulation and Release
    2016 (English)In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 49, no 18, p. 6997-7003Article in journal (Refereed) Published
    Abstract [en]

    We demonstrate a novel route for hierarchical self-assembly of sub-micrometer-sized peptide superstructures that respond to subtle changes in Zn2+ concentration. The self-assembly process is triggered by a specific folding-dependent coordination of Zn2+ by a de novo designed nonlinear helix-loop-helix peptide, resulting in a propagating fiber formation and formation of spherical superstructures. The superstructures further form larger assemblies that can be completely disassembled upon removal of Zn2+ or degradation of the nonlinear peptide. This flexible and reversible assembly strategy of the superstructures enables facile encapsulation of nanoparticles and drugs that can be released by means of different stimuli.

    Place, publisher, year, edition, pages
    AMER CHEMICAL SOC, 2016
    National Category
    Polymer Chemistry
    Identifiers
    urn:nbn:se:liu:diva-132215 (URN)10.1021/acs.macromol.6b01724 (DOI)000384399100030 ()
    Note

    Funding Agencies|Swedish Research Council [621-2011-4319]; Swedish Foundation for Strategic Research [ICA10-0002]; Linkoping University; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]

    Available from: 2016-10-26 Created: 2016-10-21 Last updated: 2017-11-29
  • 7.
    Arwin, Hans
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Magnusson, Roger
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Fernández del Río, Lia
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Landin, Jan
    Linköping University, Department of Physics, Chemistry and Biology, Ecology. Linköping University, The Institute of Technology.
    Mendoza-Galván, Arturo
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology. Unidad Queretaro, Queretaro, Mexico.
    Järrendahl, Kenneth
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Exploring polarization features in light reflection from beetles with structural colors2015In: Proc. SPIE  9429, Bioinspiration, Biomimetics, and Bioreplication 2015, SPIE - International Society for Optical Engineering, 2015, Vol. 9429, p. 942909-1-942909-13Conference paper (Refereed)
    Abstract [en]

    A Mueller matrix of a sample can be used to determine the polarization of  reflected light  for  incident light with arbitrary polarization. The polarization can be quantified  in terms of ellipticity, polarization azimuth and degree of polarization. We apply spectroscopic Mueller-matrix ellipsometry at multiple angles of incidence  to study the cuticle of beetles and derive  polarization features for incident unpolarized light.  In particular we address chiral phenomena in scarab beetles,  the origin of their structural colors and the observed high degree of circular polarization is discussed. Results from beetles in the Scarabaeidae subfamilies Cetoniinae and Rutelinae are presented including specimens with broad-band silver- or gold-like colors with metallic shine as well as specimens with narrow-band green or red reflectors. The variation of polarization with angle of incidence and occurrence of both left-handed and right-handed polarization from a single species are presented. We also use Mueller-matrix spectra in electromagnetic modeling and show how to determine structural parameters including cuticle layer thicknesses and optical properties. Interference oscillations in the observed spectra are due to allowed optical modes and we show how to develop a structural model of a cuticle based on this effect. Sum decomposition of  Mueller matrices measured on a depolarizing cuticle of a beetle is briefly discussed.

  • 8.
    Arwin, Hans
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, Faculty of Science & Engineering.
    Mendoza-Galvan, A.
    Cinvestav IPN, Mexico.
    Magnusson, Roger
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, Faculty of Science & Engineering.
    Andersson, Anette
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Landin, Jan
    Linköping University, Department of Physics, Chemistry and Biology, Ecology. Linköping University, Faculty of Science & Engineering.
    Järrendahl, Kenneth
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, Faculty of Science & Engineering.
    Garcia-Caurel, E.
    University of Paris Saclay, France.
    Ossikovski, R.
    University of Paris Saclay, France.
    Structural circular birefringence and dichroism quantified by differential decomposition of spectroscopic transmission Mueller matrices from Cetonia aurata2016In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 41, no 14, p. 3293-3296Article in journal (Refereed)
    Abstract [en]

    Transmission Mueller-matrix spectroscopic ellipsometry is applied to the cuticle of the beetle Cetonia aurata in the spectral range 300-1000 nm. The cuticle is optically reciprocal and exhibits circular Bragg filter features for green light. By using differential decomposition of the Mueller matrix, the circular and linear birefringence as well as dichroism of the beetle cuticle are quantified. A maximum value of structural optical activity of 560 degrees/mm is found. (C) 2016 Optical Society of America

  • 9.
    Askari Ghotbabadi, Sadegh
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering. University of Ulster, North Ireland.
    Ul Haq, Atta
    University of Ulster, North Ireland.
    Macias-Montero, Manuel
    University of Ulster, North Ireland.
    Levchenko, Igor
    Queensland University of Technology, Australia.
    Yu, Fengjiao
    University of St Andrews, Scotland.
    Zhou, Wuzong
    University of St Andrews, Scotland.
    (Ken) Ostrikov, Kostya
    Queensland University of Technology, Australia; Queensland University of Technology, Australia; CSIRO, Australia.
    Maguire, Paul
    University of Ulster, North Ireland.
    Svrcek, Vladimir
    National Institute Adv Ind Science and Technology, Japan.
    Mariotti, Davide
    University of Ulster, North Ireland.
    Ultra-small photoluminescent silicon-carbide nanocrystals by atmospheric-pressure plasmas2016In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, no 39, p. 17141-17149Article in journal (Refereed)
    Abstract [en]

    Highly size-controllable synthesis of free-standing perfectly crystalline silicon carbide nanocrystals has been achieved for the first time through a plasma-based bottom-up process. This low-cost, scalable, ligand-free atmospheric pressure technique allows fabrication of ultra-small (down to 1.5 nm) nanocrystals with very low level of surface contamination, leading to fundamental insights into optical properties of the nanocrystals. This is also confirmed by their exceptional photoluminescence emission yield enhanced by more than 5 times by reducing the nanocrystals sizes in the range of 1-5 nm, which is attributed to quantum confinement in ultra-small nanocrystals. This method is potentially scalable and readily extendable to a wide range of other classes of materials. Moreover, this ligand-free process can produce colloidal nanocrystals by direct deposition into liquid, onto biological materials or onto the substrate of choice to form nanocrystal films. Our simple but efficient approach based on non-equilibrium plasma environment is a response to the need of most efficient bottom-up processes in nanosynthesis and nanotechnology.

  • 10.
    Atlasov, K. A.
    et al.
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne (EPFL), Lausanne, Switzerland .
    Surrente, A.
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne (EPFL), Lausanne, Switzerland .
    Calic, M.
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne (EPFL), Lausanne, Switzerland .
    Karlsson, K Fredrik
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne (EPFL), Lausanne, Switzerland .
    Gallo, P.
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne (EPFL), Lausanne, Switzerland .
    Felici, Marco
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne (EPFL), Lausanne, Switzerland .
    Dwir, Benjamin
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne (EPFL), Lausanne, Switzerland .
    Rudra, Alok
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne (EPFL), Lausanne, Switzerland .
    Kapon, E.
    Lab. of Phys. of Nanostruct., Ecole Polytech. Fed. de Lausanne (EPFL), Lausanne, Switzerland .
    Site-controlled quantum-wire and quantum-dot photonic-crystal microcavity lasers2010In: Photonics Society Winter Topicals Meeting Series (WTM), 2010 IEEE, 2010, p. 149-150Conference paper (Refereed)
    Abstract [en]

    Based on site- and energy-controlled quantum wires (QWR) and quantum dots (QD), diverse photonic-crystal microcavity laser systems are proposed and discussed. Results demonstrating QWR lasing, cavity coupling and QD ordered arrays are presented.

  • 11.
    Bakker, Jimmy W. P.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    New methodology for optical sensing and analysis2004Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis describes the research I have done, and partly will do, during my time as a PhD student in the laboratory of Applied Optics at Linköping University. Due to circumstances beyond the scope of this book, this incorporates three quite different projects. The first two, involving gas sensing and measuring on paper with ellipsometry, have been discontinued, whereas the third one, measuring fluorescence with a computer screen and web camera, is in full progress and will be until I complete my studies.

    Thus the purpose of this work also has several aspects. Partly, it describes performed research and its results, as well as theoretical background. On the other hand, it provides practical and theoretical background necessary for future work. While the three projects are truly quite different, each of them has certain things in common with each of the other. This is certainly also true for the necessary theory. Two of them involve spectroscopic ellipsometry, for example, while another pair needs knowledge of color theory, etc. This makes it impossible to separate the projects, despite of their differences. Hopefully, these links between the different projects, connecting the different chapters, will make this work whole and consistent in its own way.

    List of papers
    1. Improvement of porous silicon based gas sensors by polymer modification
    Open this publication in new window or tab >>Improvement of porous silicon based gas sensors by polymer modification
    2003 (English)In: Physica Status Solidi (A), ISSN 0031-8965, Vol. 197, no 2, p. 378-381Article in journal (Refereed) Published
    Abstract [en]

    Gas sensing was performed using spectroscopic ellipsometry and porous silicon films. Modification of the porous layer by polymer deposition showed an increase in sensitivity to organic solvent vapor of up to 135%. The increase in sensitivity is strongly dependent on polymer concentration. At high concentrations, too much polymer is deposited, presumably blocking the pores, causing a decrease in sensitivity. At sufficiently low concentrations, the polymer causes a strong increase in sensitivity. This is assumed to be caused by the polymer being deposited inside the pores, where its interaction with the vapor influences the sensitivity. At very low concentration, the sensitivity approaches values obtained without polymer modification. The sensitivity increase is different for different vapors, pointing to possible selectivity enhancement.

    Keywords
    07.07.Df, 61.43.Gt, 78.67.Bf, 82.35.Gh
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-13772 (URN)10.1002/pssa.200306529 (DOI)
    Available from: 2004-12-10 Created: 2004-12-10 Last updated: 2013-10-14
    2. Determination of refractive index of printed and unprinted paper using spectroscopic ellipsometry.
    Open this publication in new window or tab >>Determination of refractive index of printed and unprinted paper using spectroscopic ellipsometry.
    2004 (English)In: Thin Solid Films, ISSN 0040-6090, Vol. 455-456, p. 361-365Article in journal (Refereed) Published
    Abstract [en]

    An attempt is made to address the basic physical properties of printed and unprinted paper surfaces by using spectroscopic ellipsometry in the range 300–900 nm to determine the effective complex-valued refractive index N. Some simulations to address the effect of structural properties have also been done and a qualitative comparison with some other methods, in particular Brewster angle measurements, has been made. Unprinted paper and paper printed in different colors have been studied. The measured absorption properties matched the colors of the used inks well. The effects of roughness on the determined spectra of N are discussed. Simulations show that compared to other methods, like Brewster-angle reflectometry, spectroscopic ellipsometry provides a more accurate value of N, especially in wavelength regions were the color pigments show absorption.

    Keywords
    Spectroscopic ellipsometry; Paper surfaces; Optical properties; Gloss variation
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-13773 (URN)10.1016/j.tsf.2004.01.024 (DOI)
    Available from: 2004-12-10 Created: 2004-12-10 Last updated: 2013-10-14
    3. Enhancing classification capabilities of computer screen photo-assisted fluorescence fingerprinting
    Open this publication in new window or tab >>Enhancing classification capabilities of computer screen photo-assisted fluorescence fingerprinting
    2005 (English)In: Sensors and Actuators B: Chemical, ISSN 0925-4005, Vol. 110, no 2, p. 190-194Article in journal (Refereed) Published
    Abstract [en]

    The separation of emission from transmitted light for the fingerprinting of fluorescent substances using a computer screen photo-assisted technique (CSPT) is demonstrated. CSPT is a technique for optical evaluation using a simple cell with just a standard computer set and a web camera as instrumentation. It has been demonstrated to be a versatile system for colorimetric and fluorescent fingerprinting. Here the omnidirectional property of fluorescent emission is utilized to separate it from the background, using a simple optical arrangement compatible with CSPT purposes. This enhances the classification capabilities and makes classification at sub-μM concentrations possible.

    Keywords
    Computer screen photo-assisted technique; Fluorescence; Spectral fingerprinting; Bioassays; Home tests
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-13774 (URN)10.1016/j.snb.2005.01.046 (DOI)
    Available from: 2004-12-10 Created: 2004-12-10 Last updated: 2009-09-08
  • 12.
    Bakker, Jimmy W. P.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Optical Detection Using Computer Screen Photo-assisted Techniques and Ellipsometry2006Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Two main subjects, ellipsometry and computer screen photo-assisted techniques (CSPT), form the main line in this thesis. Ellipsometry is an optical technique based on the detection of polarization changes of light upon interaction with a sample. As most optical detection techniques it is non-intrusive and an additional advantage is its high surface sensitivity: thickness resolution in the order of pm can in principle be achieved. Therefore, ellipsometry is widely used as a technique for determination of optical constants and layer thickness for thin-layer structures. Lately ellipsometry has also been proposed for sensing applications, utilizing the detection of changes in the properties of thin layers. One application is described in this thesis concerning the detection of volatile organic solvents in gas phase using modified porous silicon layers, fabricated by electrochemical etching of silicon to create nm-sized pores. This greatly increases the surface area, promoting gas detection because the number of adsorption sites increases. Other applications of ellipsometry discussed in this thesis are based on combination with CSPT.

    CSPT is a way to exploit existing optical techniques for use in low-cost applications. In CSPT the computer screen itself is used as a (programmable) light source for optical measurements. For detection a web camera can be used and the whole measurement platform is formed by the computer. Since computers are available almost everywhere, this is a promising way to create optical measurement techniques for widespread use, for example in home-diagnostics. Since the only thing that needs to be added is a sample holder governing the physical or chemical process and directing the light, the cost can be kept very low. First, the use of CSPT for the measurement of fluorescence is described. Fluorescence is used in many detection applications, usually by chemically attaching a fluorescent marker molecule to a suitable species in the process and monitoring the fluorescent emission. The detection of fluorescence is shown to be possible using CSPT, first in a cuvette-based setup, then using a custom designed micro array. In the latter, polarizers were used for contrast enhancement, which in turn led to the implementation of an existing idea to test CSPT for ellipsometry measurements. In a first demonstration, involving thickness measurement of silicon dioxide on silicon, a thickness resolution in the order of nm was already achieved. After improvement of the system, gradients in protein layers could be detected, opening the door toward biosensor applications. Some further development will be needed to make the CSPT applications described here ready for the market, but the results so far are certainly promising.

    List of papers
    1. Improvement of porous silicon based gas sensors by polymer modification
    Open this publication in new window or tab >>Improvement of porous silicon based gas sensors by polymer modification
    2003 (English)In: Physica Status Solidi (A), ISSN 0031-8965, Vol. 197, no 2, p. 378-381Article in journal (Refereed) Published
    Abstract [en]

    Gas sensing was performed using spectroscopic ellipsometry and porous silicon films. Modification of the porous layer by polymer deposition showed an increase in sensitivity to organic solvent vapor of up to 135%. The increase in sensitivity is strongly dependent on polymer concentration. At high concentrations, too much polymer is deposited, presumably blocking the pores, causing a decrease in sensitivity. At sufficiently low concentrations, the polymer causes a strong increase in sensitivity. This is assumed to be caused by the polymer being deposited inside the pores, where its interaction with the vapor influences the sensitivity. At very low concentration, the sensitivity approaches values obtained without polymer modification. The sensitivity increase is different for different vapors, pointing to possible selectivity enhancement.

    Keywords
    07.07.Df, 61.43.Gt, 78.67.Bf, 82.35.Gh
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-13772 (URN)10.1002/pssa.200306529 (DOI)
    Available from: 2004-12-10 Created: 2004-12-10 Last updated: 2013-10-14
    2. Enhancing classification capabilities of computer screen photo-assisted fluorescence fingerprinting
    Open this publication in new window or tab >>Enhancing classification capabilities of computer screen photo-assisted fluorescence fingerprinting
    2005 (English)In: Sensors and Actuators B: Chemical, ISSN 0925-4005, Vol. 110, no 2, p. 190-194Article in journal (Refereed) Published
    Abstract [en]

    The separation of emission from transmitted light for the fingerprinting of fluorescent substances using a computer screen photo-assisted technique (CSPT) is demonstrated. CSPT is a technique for optical evaluation using a simple cell with just a standard computer set and a web camera as instrumentation. It has been demonstrated to be a versatile system for colorimetric and fluorescent fingerprinting. Here the omnidirectional property of fluorescent emission is utilized to separate it from the background, using a simple optical arrangement compatible with CSPT purposes. This enhances the classification capabilities and makes classification at sub-μM concentrations possible.

    Keywords
    Computer screen photo-assisted technique; Fluorescence; Spectral fingerprinting; Bioassays; Home tests
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-13774 (URN)10.1016/j.snb.2005.01.046 (DOI)
    Available from: 2004-12-10 Created: 2004-12-10 Last updated: 2009-09-08
    3. Two-dimensional micro array fluorescence fingerprinting with a computer screen photo-assisted technique
    Open this publication in new window or tab >>Two-dimensional micro array fluorescence fingerprinting with a computer screen photo-assisted technique
    2005 (English)In: Spectral Imaging: Instrumentation, Applications, and Analysis III, 2005, p. 9-15Conference paper, Published paper (Other academic)
    Abstract [en]

    Detection and classification of fluorescent dyes are demonstrated using a computer screen photo-assisted technique (CSPT). This technique has previously been demonstrated for analyzing fluorescence from 96 wells microtiterplates (200 µl per well) and from a single cuvette with some optics to enhance sensitivity. In this work a custom designed array of wells with a volume of approximately 1 mu;l is used. In order to measure such small volumes without saturating the detector, the transmitted light is masked by placing the sample between two crossed polarizers. This arrangement blocks nearly all the transmitted light, while the emitted light, which is nearly unpolarized, can still be detected. The lowest amount (concentration x volume) of analyte detectable in this setup is about 40 times smaller than in the previous setups.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-13835 (URN)10.1117/12.589586 (DOI)
    Available from: 2006-05-04 Created: 2006-05-04 Last updated: 2009-04-28
    4. Computer screen photo-assisted off-null ellipsometry
    Open this publication in new window or tab >>Computer screen photo-assisted off-null ellipsometry
    2006 (English)In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 45, no 30, p. 7795-7799Article in journal (Refereed) Published
    Abstract [en]

    The ellipsometric measurement of thickness is demonstrated using a computer screen as a light source and a webcam as a detector, adding imaging off-null ellipsometry to the range of available computer screen photoassisted techniques. The results show good qualitative agreement with a simplified theoretical model and a thickness resolution in the nanometer range is achieved. The presented model can be used to optimize the setup for sensitivity. Since the computer screen serves as a homogeneous large area illumination source, which can be tuned to different intensities for different parts of the sample, a large sensitivity range can be obtained without sacrificing thickness resolution.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-13836 (URN)10.1364/AO.45.007795 (DOI)
    Available from: 2006-05-04 Created: 2006-05-04 Last updated: 2017-12-13
    5. Non-labeled immunodetection with a computer screen photo-assisted technique
    Open this publication in new window or tab >>Non-labeled immunodetection with a computer screen photo-assisted technique
    Manuscript (Other academic)
    Identifiers
    urn:nbn:se:liu:diva-13837 (URN)
    Available from: 2006-05-04 Created: 2006-05-04 Last updated: 2010-01-13
  • 13.
    Beličev, P.P.
    et al.
    University of Belgrade, Serbia.
    Gligorić, G.
    University of Belgrade, Serbia.
    Radosavljević, A.
    University of Belgrade, Serbia.
    Maluckov, A.
    University of Belgrade, Serbia.
    Stepić, M.
    University of Belgrade, Serbia.
    Johansson, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Light Localization in Nonlinear Binary Two-Dimensional Lieb Lattices2016In: Abstract Book of RIAO-OPTILAS 2016 / [ed] Moraga, P. and Saavedra, C, Concepción - Chile: CEFOP-UdeC , 2016, p. 80-80Conference paper (Refereed)
    Abstract [en]

    Light localization in photonic lattices (PLs) is a well-known phenomenon which has been investigated during decades. It has been shown that light localization in the linear regime can be achieved by designing PLs with specific geometries, instead of embedding defects or disorder in otherwise periodic lattices [1]. These geometries provide conditions necessary for destructive wave interference, leading to formation of a perfectly flat (dispersionless) energy band. Eigenvectors associated to the flat-band (FB) eigenfrequencies are entirely degenerate and compact states (FB modes) and any superposition of them is nondiffracting. One of the simplest FB lattice patterns is the two-dimensional (2D) Lieb lattice [2,3] in which the primitive cell contains three sites. By appropriate spatial repetition of this fundamental block, it is possible to achieve a FB in the energy spectrum. Light confinement in PLs can also be a consequence of the interplay between nonlinearity and diffraction when these effects cancel each other, leading to formation of solitons. Recently, it has been reported that nonlinearity and “binarism” in quasi-one-dimensional FB systems can increase the range of existence and stability of FB ring modes [4].

    We model a 2D binary Lieb lattice with nonlinearity of Kerr type and analyse numerically and analytically the existence, stability and dynamical properties of various localized modes found to emerge in spectrum. From the derived dispersion relation we found that binarism does not affect the FB. However, due to the presence of additional periodicity, new gaps occur in the energy spectrum above and below the FB and their widths depend on the ratio between coupling constants. Like in the uniform Lieb lattice, we found eigenmodes in the form of a staggered four-peak “ring” structure, but only under certain conditions which require a particular relation between the field amplitudes in neighbouring sites. In the nonlinear regime, ring modes survive in the uniform Lieb lattice but lose their stability moving away from the FB. On the other hand, nonlinearity destroys the existence of ring solutions in the binary Lieb lattice, leading to a new class of stable localized solutions which can be found in minigaps. As in previous kagome and ladder binary nonlinear strips [4], it is shown that the binarism increases the existence range of stable nonlinear localized solutions.

    References

    [1] R. A. Vicencio, M. Johansson, Physical Review A 87, 061803(R) (2013).

    [2] R. A. Vicencio et al., Physical Review Letters 114, 245503 (2015).

    [3] D. Leykam, O. Bahat-Treidel, A. S. Desyatnikov, Physical Review A 86, 031805(R) (2012).

    [4] P. P. Beličev et al., Physical Review E 92, 052916 (2015).

  • 14.
    Beličev, P.P.
    et al.
    University of Belgrade, Serbia..
    Gligorić, G.
    University of Belgrade, Serbia..
    Radosavljević, A.
    University of Belgrade, Serbia..
    Maluckov, A.
    University of Belgrade, Serbia..
    Stepić, M.
    University of Belgrade, Serbia..
    Vicencio, R.A.
    University of Chile, Chile..
    Johansson, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    On localized modes in nonlinear binary kagome ribbons2015Conference paper (Other academic)
    Abstract [en]

    One of the attractive two-dimensional [2D] lattice configurations is characterized by kagome geometry. The specific arrangement of its elements, i.e. waveguides, in the form of periodic hexagons renders completely flat the first energy band in linear case. As a consequence, the localized ring-like eigenmodes belonging to the lowest energy state propagate without diffraction through the system [1, 2]. Here we study kagome ribbon [3], which can be interpreted as one-dimensional counterpart of the standard 2D kagome lattice, and can be fabricated by dint of the direct femtosecond laser inscription [4, 5].

    The existence, stability and dynamical properties of various localized modes in binary kagome ribbon with defocusing Kerr type of nonlinearity have been explored, both numerically and analytically. We derived the corresponding dispersion relation and the bandgap spectrum, confirmed the opening of mini-gaps in it and found several types of stable ring-like modes to exist: staggered, unstaggered and vortex. Beside these nonlinear mode configurations occurring in a semi-infinite gap, we investigated features of "hourglass" solutions, identified in [3] as interesting structures when kagome lattice dimensionality is reduced to 1D. In nonlinear binary kagome ribbon dynamically stable propagation of unstaggered rings, vortex modes with certain topological charge and hourglass solutions are observed, while the staggered ring solutions are destabilized. In addition, we examined possibility to generate stable propagating solitary modes inside the first mini-gap and found that these mode patterns localize within sites mutually coupled by smaller coupling constant. The last feature is opposite to the nonlinear localized solutions found in the semi-infinite gap.

    REFERENCES

    [1] R. A. Vicencio, C. Mejía-Cortés, J. Opt. 16, 015706 (2014).

    [2] R. A. Vicencio, M. Johansson, Phys. Rev. A 87, R061803 (2013).

    [3] M. Molina, Phys. Lett. A 376, 3458 (2012).

    [4] K. Davies et al., Opt. Lett. 21, 1729 (1996).

    [5] K. Itoh et al., MRS Bulletin 31, 620 (2006).

  • 15.
    Bergström, Anna
    Linköping University, Department of Physics, Chemistry and Biology.
    SPR Sensor Surfaces based on Self-Assembled Monolayers2009Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The study and understanding of molecular interactions is fundamentally important in today's field of life sciences and there is a demand for well designed surfaces for biosensor applications. The biosensor has to be able to detect specific molecular interactions, while non-specific binding of other substances to the sensor surface should be kept to a minimum.                                                                                                                                                                                The objective of this master´s thesis was to design sensor surfaces based on self-assembled monolayers (SAMs) and evaluate their structural characteristics as well as their performance in Biacore systems. By mixing different oligo (ethylene glycol) terminated thiol compounds in the SAMs, the density of functional groups for bimolecular attachment could be controlled.  Structural characteristics of the SAMs were studied using Ellipsometry, Contact Angle Goniometry, IRAS and XPS. Surfaces showing promising results were examined further with Surface Plasmon Resonance in Biacore instruments.

    Mixed SAM surfaces with a tailored degree of functional COOH groups could be prepared. The surfaces showed promising characteristics in terms of stability, immobilization capacity of biomolecules, non-specific binding and kinetic assay performance, while further work needs to be dedicated to the improvement of their storage stability. In conclusion, the SAM based sensor surfaces studied in this thesis are interesting candidates for Biacore applications.

  • 16.
    Bi, Shubo
    et al.
    Shanghai Univ, Peoples R China; Sci and Technol Near Surface Detect Lab, Peoples R China.
    Wang, Chi
    Shanghai Univ, Peoples R China; Sci and Technol Near Surface Detect Lab, Peoples R China.
    Zhu, Jun
    Sci and Technol Near Surface Detect Lab, Peoples R China.
    Yuan, Zhiwen
    Sci and Technol Near Surface Detect Lab, Peoples R China.
    Yu, Yingjie
    Shanghai Univ, Peoples R China.
    Valyukh, Sergiy
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Asundi, Anand
    Nanyang Technol Univ, Singapore.
    Influence of no-core fiber on the focusing performance of an ultra-small gradient-index fiber probe2018In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 107, p. 46-53Article in journal (Refereed)
    Abstract [en]

    The light-beam expansion effect of a no-core fiber on the focusing performance of an ultra-small gradient-index fiber probe is investigated with a view to optimizing the optical performance of such probes. By taking the variable relationship between the focusing performance (including the working distance and the focusing spot size) of the probe and the length of the no-core fiber as the criterion, the effective beam expansion length of the no-core fiber in the ultra-small gradient-index fiber probe is calculated based on the basic properties of the Gaussian beam. Verification and analysis are done by numerical calculations and experimental measurements, respectively. The obtained results show that the working distance of an ultra-small gradient-index fiber probe can be increased effectively by adding a no-core fiber; however, this will lead to increasing the focusing spot size. For the parameters of the fiber probe studied here, the effective beam expansion length of the no-core fiber spacer is less than 0.357 mm. (C) 2018 Elsevier Ltd. All rights reserved.

  • 17.
    Borgh, Annika
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Biomimetic surfaces: Preparation, characterization and application2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis describes the preparation, characterization and application of a few biomimetic surfaces. Biomimetics is a modern development of the ancient Greek concept of mimesis, i.e. man-made imitation of nature. The emphasis has been on the preparation and characterization of two types of model systems with properties inspired by nature with future applications in bioanalysis, biosensors and antifreeze materials. One type of model system involves phosphorylated surfaces; the other consists of surfaces mimicking antifreeze (glyco)proteins. The surfaces were made by chemisorbing organosulfur substances to a gold surface into monomolecular layers, so called self-assembled monolayers (SAMs). The physicochemical properties of the SAMs were thoroughly characterized with null ellipsometry, contact angle goniometry, x-ray photoelectron spectroscopy and infrared spectroscopy prior to application.

    The work on antifreeze surfaces was inspired by the structural properties of antifreeze (glyco)proteins, which can be found in polar fish. Two model systems were developed and studied with respect to ice nucleation of condensed water layers. One was designed to mimic the active domain of antifreeze glycoproteins (AFGP) and the other mimicked type I antifreeze proteins (AFP I). Subsequent ice nucleation studies showed a significant difference between the AFGP model and a (OH/CH3) reference system displaying identical wetting properties, whereas the AFP I model was indistinguishable from the reference system.

    The model systems with phosphorylated surfaces were inspired from phosphorylations and biomineralization. Two systems were developed, short- and long-chained amino acid analogues, with and without a phosphate group. A novel approach with protected groups before attachment to gold were developed for the long-chained analogues. The protective groups could be removed successfully after assembly. The long-chained SAMs were evaluated with electrochemical methods and significantly higher capacitance values were observed for the phosphorylated SAMs compared to the non-phosphorylated.

    List of papers
    1. A new route to the formation of biomimetic phosphate assemblies on gold: Synthesis and characterization
    Open this publication in new window or tab >>A new route to the formation of biomimetic phosphate assemblies on gold: Synthesis and characterization
    Show others...
    2006 (English)In: Journal of Colloid and Interface Science, ISSN 1095-7103, Vol. 295, no 1, p. 41-49Article in journal (Refereed) Published
    Abstract [en]

    A biomimetic model system based on long-chain alkanethiols tailored with serine, threonine and tyrosine side-chain groups is created as a platform for the study of phosphorylated amino acids. The phosphorylated analogues are synthesized with protective tert-butyl groups that after assembly on thin polycrystalline gold films are removed in an acidic deprotection solution to form the corresponding phosphate self-assembled monolayers (SAMs). The SAMs are thoroughly characterized with null ellipsometry, contact angle goniometry, infrared reflection–absorption spectroscopy and X-ray photoelectron spectroscopy. The assembly and the subsequent deprotection process are optimized with respect to molecular orientation and chain conformation by varying the incubation time and the exposure time to the deprotection solution. The high quality of the generated SAMs suggests that the present assembly/deprotection approach is an attractive alternative when traditional synthetic routes become demanding because of solubility problems.

    Keywords
    SAM; Thiols; Gold; Phosphorylated amino acids; Surface deprotection scheme
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-14334 (URN)10.1016/j.jcis.2005.08.026 (DOI)
    Available from: 2007-03-16 Created: 2007-03-16 Last updated: 2010-09-06
    2. Electrochemical Evaluation of the Interfacial Capacitance upon Phosphorylation of Amino Acid Analogue Molecular Films
    Open this publication in new window or tab >>Electrochemical Evaluation of the Interfacial Capacitance upon Phosphorylation of Amino Acid Analogue Molecular Films
    Show others...
    2001 (English)In: Analytical Chemistry, ISSN 0003-2700, Vol. 73, no 18, p. 4463-4468Article in journal (Refereed) Published
    Abstract [en]

    An approach based on electrochemistry to differentiate between phosphorylated and nonphosphorylated amino acid analogues adsorbed on gold is presented. Analogues of serine, threonine, and tyrosine, containing thiohexadecyl headgroups, were synthesized and assembled on gold, and the surface capacitance was evaluated using electrochemical impedance spectroscopy. A procedure for deprotection of tert-butyl phosphate protecting groups, on the monolayer, is also described. Characterizations of the assembled analogues by cyclic voltammetry, infrared spectroscopy, and ellipsometry are used to confirm the insulating properties of the monolayers and the outcome of surface modifications. The results from cyclic voltammetry show good insulating properties for the monolayers even after phosphate deprotection. The infrared measurements reveal well-ordered monolayers, and the thickness from ellipsometry is in good agreement with expectations from molecular modeling. The impedance experiments show a capacitance increase up to 0.6 μF/cm2 as phosphate groups are introduced. The results in this study indicate the possibility of using a surface chemical and impedance spectroscopy approach to detect the kinase/phosphatase activity and kinetics involved in phosphorylation reactions.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-14335 (URN)10.1021/ac010487+ (DOI)
    Available from: 2007-03-16 Created: 2007-03-16 Last updated: 2009-05-11
    3. Synthesis and Monolayer Characterization of Phosphorylated Amino Acid Analogs
    Open this publication in new window or tab >>Synthesis and Monolayer Characterization of Phosphorylated Amino Acid Analogs
    2002 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 254, no 2, p. 322-330Article in journal (Refereed) Published
    Abstract [en]

    The synthesis of a series of thiols containing phosphorylated and non-phosphorylated serine, threonine, and tyrosine amino acid residues is described. The synthesized molecules, based on 3-mercaptopropionic acid, were assembled onto gold and subsequently characterized using infrared reflection-absorption spectroscopy, ellipsometry, X-ray photoelectron spectroscopy, and contact angle goniometry. The ellipsometric analysis indicates that they form densely packed and well-oriented monolayers on gold, with thicknesses that are in good agreement with estimated values from space-filling models. The bulky and space-demanding phosphorylated threonine analog was, however, found to be an exception. The increase in layer thickness when adding a phosphate group to the threonine is only 35% of that observed for the two other analogs. A detailed infrared examination of the influence of cation coordination to the phosphorylated serine analog using calcium and magnesium reveals structural similarities to those of the inorganic phosphate compound calcium hydroxy apatite. We furthermore discuss the application of these monolayers as soft templates for biomineralization.

    Place, publisher, year, edition, pages
    Maryland Heights, MO, United States: Academic Press, 2002
    Keywords
    SAM; phosphorylated amino acid; phosphate layer; alkanethiols; gold; counterion influence
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-14336 (URN)10.1006/jcis.2002.8576 (DOI)000178935400016 ()
    Available from: 2007-03-16 Created: 2007-03-16 Last updated: 2017-12-13Bibliographically approved
    4. Mimicking the properties of antifreeze glycoproteins: synthesis and characterization of a model system for ice nucleation and antifreeze studies
    Open this publication in new window or tab >>Mimicking the properties of antifreeze glycoproteins: synthesis and characterization of a model system for ice nucleation and antifreeze studies
    2005 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 109, no 33, p. 15849-15859Article in journal (Refereed) Published
    Abstract [en]

    Synthesis of β-D-Gal-(1 → 3)-β-D-GalNAc coupled to HOC2H4NHCOC15H30SH is described. This compound was coadsorbed at various proportions with C2H5OC2H4NHCOC15H30SH to form statistically mixed self-assembled monolayers (SAMs) on gold in an attempt to mimic the properties of the active domain in antifreeze glycoproteins (AFGPs). The monolayers were characterized by null ellipsometry, contact angle goniometry, X-ray photoelectron spectroscopy, and infrared reflection−absorption spectroscopy. The disaccharide compound adsorbed preferentially, and SAMs prepared at a solution molar ratio >0.3 displayed total wetting. The mixed SAMs showed well-organized alkyl chains up to a disaccharide surface fraction of 0.8. The amount of gauche conformers in the alkyls increased rapidly above this point, and the monolayers became disordered and less densely packed. Furthermore, the generated mixed SAMs were subjected to water vapor at constant relative humidity and the subsequent ice crystallization on a cooled substrate was monitored via an optical microscope. Interestingly, rapid crystallization occurred within a narrow range of temperatures on mixed SAMs with a high disaccharide content, surface fraction >0.3. The reported crystallization temperatures and the ice layer topography were compared with results obtained for a much simpler reference system composed of −OH/−CH3 terminated n-alkanethiols in order to account for changes in topography of the water/ice layer with surface energy. Although preliminary, the obtained results can be useful in the search for the molecular mechanism behind the antifreeze activity of AFGPs.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-14337 (URN)10.1021/jp050752l (DOI)
    Available from: 2007-03-16 Created: 2007-03-16 Last updated: 2017-12-13
    5. Biomimetic Surfaces for Ice Interaction Studies
    Open this publication in new window or tab >>Biomimetic Surfaces for Ice Interaction Studies
    Manuscript (Other academic)
    Identifiers
    urn:nbn:se:liu:diva-14338 (URN)
    Available from: 2007-03-16 Created: 2007-03-16 Last updated: 2010-01-13
  • 18.
    Bosma, Tom
    et al.
    Univ Groningen, Netherlands.
    Lof, Gerrit J. J.
    Univ Groningen, Netherlands.
    Gilardoni, Carmem M.
    Univ Groningen, Netherlands.
    Zwier, Olger V
    Univ Groningen, Netherlands.
    Hendriks, Freddie
    Univ Groningen, Netherlands.
    Magnusson, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. Norstel AB, Sweden.
    Ellison, Alexandre
    Norstel AB, Sweden.
    Gällström, Andreas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. Saab Dynam AB, SE-58188 Linkoping, Sweden.
    Ivanov, Ivan Gueorguiev
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Nguyen, Son Tien
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Havenith, Remco W. A.
    Univ Groningen, Netherlands; Univ Groningen, Netherlands; Univ Ghent, Belgium.
    van der Wal, Caspar H.
    Univ Groningen, Netherlands.
    Identification and tunable optical coherent control of transition-metal spins in silicon carbide2018In: NPJ QUANTUM INFORMATION, ISSN 2056-6387, Vol. 4, article id 48Article in journal (Refereed)
    Abstract [en]

    Color centers in wide-bandgap semiconductors are attractive systems for quantum technologies since they can combine long-coherent electronic spin and bright optical properties. Several suitable centers have been identified, most famously the nitrogen-vacancy defect in diamond. However, integration in communication technology is hindered by the fact that their optical transitions lie outside telecom wavelength bands. Several transition-metal impurities in silicon carbide do emit at and near telecom wavelengths, but knowledge about their spin and optical properties is incomplete. We present all-optical identification and coherent control of molybdenum-impurity spins in silicon carbide with transitions at near-infrared wavelengths. Our results identify spin S= 1/2 for both the electronic ground and excited state, with highly anisotropic spin properties that we apply for implementing optical control of ground-state spin coherence. Our results show optical lifetimes of similar to 60 ns and inhomogeneous spin dephasing times of similar to 0.3 mu S, establishing relevance for quantum spin-photon interfacing.

  • 19.
    Börjesson, Anders
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Erdtman, Edvin
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ahlström, Peter
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Berlin, Mikael
    Tetra Pak Packaging Solutions AB, Ruben Rausings gata, Lund, Sweden.
    Andersson, Thorbjörn
    Tetra Pak Packaging Solutions AB, Ruben Rausings gata, Lund, Sweden.
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Molecular modelling of oxygen and water permeation in polyethylene2013In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 54, no 12, p. 2988-Article in journal (Refereed)
    Abstract [en]

    Monte Carlo and molecular dynamics simulations were performed to calculate solubility, S, and diffusion, D, coefficients of oxygen and water in polyethylene, and to obtain a molecular-level understanding of the diffusion mechanism. The permeation coefficient, P, was calculated from the product of S and D. The AMBER force field, which yields the correct polymer densities under the conditions studied, was used for the simulations, and it was observed that the results were not sensitive to the inclusion of atomic charges in the force field. The simulated S for oxygen and water are higher and lower than experimental data, respectively. The calculated diffusion coefficients are in good agreement with experimental data. Possible reasons for the discrepancy in the simulated and experimental solubilities, which results in discrepancies in the permeation coefficients, are discussed. The diffusion of both penetrants occurs mainly by large amplitude, infrequent jumps of the molecules through the polymer matrix.

  • 20.
    Carlsson, Andreas
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering. Swedish National Forens Centre NFC, Linkoping, Sweden.
    Synthesis and spectroscopic characterization of emerging synthetic cannabinoids and cathinones2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The application of different analytical techniques is fundamental in forensic drug analysis. In the wake of the occurrence of large numbers of new psychoactive substances possessing similar chemical structures as already known ones, focus has been placed on applied criteria for their univocal identification. These criteria vary, obviously, depending on the applied technique and analytical approach. However, when two or more substances are proven to have similar analytical properties, these criteria no longer apply, which imply that complementary techniques have to be used in their differentiation.

    This work describes the synthesis of some structural analogues to synthetic cannabinoids and cathinones based on the evolving patterns in the illicit drug market. Six synthetic cannabinoids and six synthetic cathinones were synthesized, that, at the time for this study, were not as yet found in drug seizures. Further, a selection of their spectroscopic data is compared to those of already existing analogues; mainly isomers and homologues. The applied techniques were mass spectrometry (MS), Fourier transformed infrared (FTIR, gas phase) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. In total, 59 different compounds were analyzed with the  selected techniques.

    The results from comparison of spectroscopic data showed that isomeric substances may in some cases be difficult to unambiguously identify based only on their GC-MS EI spectra. On the other hand, GC-FTIR demonstrated more distinguishable spectra. The spectra for the homologous compounds showed however, that the GC-FTIR technique was less successful compared to GC-MS. Also a pronounced fragmentation pattern for some of the cathinones was found.

    In conclusion, this thesis highlights the importance of using complementary techniques for the univocal identification of synthetic cannabinoids and cathinones. By increasing the number of analogues investigated, the more may be learnt about the capabilities of different techniques for structural differentiations, and thereby providing important identification criteria leading to trustworthy forensic evidence.

    List of papers
    1. Prediction of designer drugs: synthesis and spectroscopic analysis of synthetic cannabinoid analogues of 1H-indol-3-yl(2,2,3,3-tetramethylcyclopropyl) methanone and 1H-indol-3-yl(adamantan-1-yl)methanone
    Open this publication in new window or tab >>Prediction of designer drugs: synthesis and spectroscopic analysis of synthetic cannabinoid analogues of 1H-indol-3-yl(2,2,3,3-tetramethylcyclopropyl) methanone and 1H-indol-3-yl(adamantan-1-yl)methanone
    Show others...
    2016 (English)In: Drug Testing and Analysis, ISSN 1942-7603, E-ISSN 1942-7611, Vol. 8, no 10, p. 1015-1029Article in journal (Refereed) Published
    Abstract [en]

    In this work, emergence patterns of synthetic cannabinoids were utilized in an attempt to predict those that may appear on the drug market in the future. Based on this information, two base structures of the synthetic cannabinoid analogues - (1H-indol-3-yl (2,2,3,3-tetramethylcyclopropyl) methanone and 1H-indol-3-yl(adamantan-1-yl)methanone) - together with three substituents butyl, 4-fluorobutyl and ethyl tetrahydropyran - were selected for synthesis. This resulted in a total of six synthetic cannabinoid analogues that to the authors knowledge have not yet appeared on the drug market. Spectroscopic data, including nuclearmagnetic resonance (NMR), mass spectrometry (MS), and Fourier transforminfrared (FTIR) spectroscopy (solid and gas phase), are presented for the synthesized analogues and some additional related cannabinoids. In this context, the suitability of the employed techniques for the identification of unknowns is discussed and the use of GC-FTIR as a secondary complementary technique to GC-MS is addressed. Examples of compounds that are difficult to differentiate by their mass spectra, but can be distinguished based upon their gas phase FTIR spectra are presented. Conversely, structural homologueswhere mass spectra aremore powerful than gas phase FTIR spectra for unambiguous assignments are also exemplified. This work further emphasizes that a combination of several techniques is the key to success in structural elucidations. Copyright (C) 2015 John Wiley amp; Sons, Ltd.

    Place, publisher, year, edition, pages
    WILEY-BLACKWELL, 2016
    Keywords
    drug analysis; proactive; synthetic cannabinoids; synthesis; mass spectrometry
    National Category
    Pharmaceutical Sciences
    Identifiers
    urn:nbn:se:liu:diva-132473 (URN)10.1002/dta.1904 (DOI)000384806400003 ()26526273 (PubMedID)
    Note

    Funding Agencies|Swedish Contingencies Agency (MSB)

    Available from: 2016-11-13 Created: 2016-11-12 Last updated: 2018-01-13
  • 21.
    Charalambidis, Georgios
    et al.
    University of Crete, Greece.
    Georgilis, Evangelos
    University of Crete, Greece; Fdn Research and Technology Hellas FORTH, Greece.
    Panda, Manas K.
    University of Crete, Greece; CSIR NIIST, India.
    Anson, Christopher E.
    Karlsruhe Institute Technology, Germany.
    Powell, Annie K.
    Karlsruhe Institute Technology, Germany; Karlsruhe Institute Technology, Germany.
    Doyle, Stephen
    Karlsruhe Institute Technology, Germany; Karlsruhe Institute Technology, Germany.
    Moss, David
    Karlsruhe Institute Technology, Germany; Karlsruhe Institute Technology, Germany.
    Jochum, Tobias
    Karlsruhe Institute Technology, Germany; Karlsruhe Institute Technology, Germany; Abcr GmbH, Germany.
    Horton, Peter N.
    University of Southampton, England.
    Coles, Simon J.
    University of Southampton, England.
    Linares, Mathieu
    Linköping University, Department of Physics, Chemistry and Biology, Bioinformatics. Linköping University, Faculty of Science & Engineering.
    Beljonne, David
    University of Mons UMONS, Belgium; University of Mons UMONS, Belgium.
    Naubron, Jean-Valere
    Aix Marseille University, France.
    Conradt, Jonas
    Karlsruhe Institute Technology, Germany; Karlsruhe Institute Technology, Germany.
    Kalt, Heinz
    Karlsruhe Institute Technology, Germany; Karlsruhe Institute Technology, Germany.
    Mitraki, Anna
    University of Crete, Greece; Fdn Research and Technology Hellas FORTH, Greece.
    Coutsolelos, Athanassios G.
    University of Crete, Greece.
    Silviu Balaban, Teodor
    Aix Marseille University, France.
    A switchable self-assembling and disassembling chiral system based on a porphyrin-substituted phenylalanine-phenylalanine motif2016In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 7, no 12657Article in journal (Refereed)
    Abstract [en]

    Artificial light-harvesting systems have until now not been able to self-assemble into structures with a large photon capture cross-section that upon a stimulus reversibly can switch into an inactive state. Here we describe a simple and robust FLFL-dipeptide construct to which a meso-tetraphenylporphyrin has been appended and which self-assembles to fibrils, platelets or nanospheres depending on the solvent composition. The fibrils, functioning as quenched antennas, give intense excitonic couplets in the electronic circular dichroism spectra which are mirror imaged if the unnatural FDFD-analogue is used. By slightly increasing the solvent polarity, these light-harvesting fibres disassemble to spherical structures with silent electronic circular dichroism spectra but which fluoresce. Upon further dilution with the nonpolar solvent, the intense Cotton effects are recovered, thus proving a reversible switching. A single crystal X-ray structure shows a head-to-head arrangement of porphyrins that explains both their excitonic coupling and quenched fluorescence.

  • 22.
    Chateau, Denis
    et al.
    Laboratoire de Chimie, Université de Lyon, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1.
    Liotta, Adrien
    Laboratoire de Chimie, Université de Lyon, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1.
    Lundén, Hampus
    Electrooptical Systems, Swedish Defence Research Agency (FOI).
    Lerouge, Frederic
    Laboratoire de Chimie, Université de Lyon, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1.
    Chaput, Frederic
    Laboratoire de Chimie, Université de Lyon, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1.
    Krein, Douglas
    Air Force Research Laboratory.
    Cooper, Thomas
    Air Force Research Laboratory.
    Lopes, Cesar
    Electrooptical Systems, Swedish Defence Research Agency (FOI).
    El-Amay, Ali A. G.
    Department on Physics, Norwegian University of Science and Technology.
    Lindgren, Mikael
    Department on Physics, Norwegian University of Science and Technology.
    Parola, Stephane
    Laboratoire de Chimie, Université de Lyon, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1.
    Long Distance Enhancement of Nonlinear Optical Properties Using Low Concentration of Plasmonic Nanostructures in Dye Doped Monolithic Sol-Gel Materials.2016In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 26, no 33, p. 10Article in journal (Refereed)
    Abstract [en]

    Monolithic sol-gel silica composites incorporating platinum-based chromophores and various types of gold nanoparticles (AuNPs) are prepared and polished to high optical quality. Their photophysical properties are investigated. The glass materials show well-defined localized surface plasmon resonance (SPR) absorbance from the visible to NIR. No redshifts of the AuNP plasmon absorption peaks due to the increase in nanoparticle doping concentration are observed in the glasses, proving that no or very small SPR coupling effects occur between the AuNPs. At 600 nm excitation, but not at 532 nm, the AuNPs improve the nonlinear absorption performance of glasses codoped with 50 × 10−3 m of a Pt-acetylide chromophore. The glasses doped with lower concentrations of AuNPs (2-5 μm average distance) and 50 × 10−3 m in chromophore, show a marked improvement in nonlinear absorption, with no or only small improvement for the more highly AuNP doped glasses. This study shows the importance of excitation wavelength and nanoparticle concentration for composite systems employing AuNPs to improve two-photon absorption of chromophores. [ABSTRACT FROM AUTHOR]

  • 23.
    Chen, Shula
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Jansson, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Stehr, Jan Eric
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Huang, Yuqing
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Ishikawa, Fumitaro
    Ehime University, Japan.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Dilute Nitride Nanowire Lasers Based on a GaAs/GaNAs Core/Shell Structure2017In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 17, no 3, p. 1775-1781Article in journal (Refereed)
    Abstract [en]

    Nanowire (NW) lasers operating in the near infrared spectral range are of significant technological importance for applications in telecommunications, sensing, and medical diagnostics. So far, lasing within this spectral range has been achieved using GaAs/AlGaAs, GaAs/GaAsP, and InGaAs/GaAs core/shell NWs. Another promising III-V material, not yet explored in its lasing capacity, is the dilute nitride GaNAs. In this work, we demonstrate, for the first time, optically pumped lasing from the GaNAs shell of a single GaAs/GaNAs core/shell NW. The characteristic "S"-shaped pump power dependence of the lasing intensity, with the concomitant line width narrowing, is observed, which yields a threshold gain, g(th), of 3300 cm(-1) and a spontaneous emission coupling factor beta, of 0.045. The dominant lasing peak is identified to arise from the HE21b, cavity mode, as determined from its pronounced emission polarization along the NW axis combined with theoretical calculations of lasing threshold for guided modes inside the nanowire. Even without intentional pas sivation of the NW surface, the lasing emission can be sustained up to 150 K. This is facilitated by the improved surface quality due to nitrogen incorporation, which partly suppresses the surface-related nonradiative recombination centers via nitridation. Our work therefore represents the first step toward development of room-temperature infrared NW lasers based on dilute nitrides with extended tunability in the lasing wavelength.

  • 24.
    Dahlqvist, Martin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Meshkian, Rahele
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Tao, Quanzheng
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Prediction and synthesis of a family of atomic laminate phases with Kagome-like and in-plane chemical ordering2017In: Science Advances, ISSN 0036-8156, E-ISSN 2375-2548, Vol. 3, no 7, article id e1700642Article in journal (Refereed)
    Abstract [en]

    The enigma of MAX phases and their hybrids prevails. We probe transition metal (M) alloying in MAX phases for metal size, electronegativity, and electron configuration, and discover ordering in these MAX hybrids, namely, (V2/3Zr1/3)(2)AlC and (Mo2/3Y1/3)(2)AlC. Predictive theory and verifying materials synthesis, including a judicious choice of alloying M from groups III to VI and periods 4 and 5, indicate a potentially large family of thermodynamically stable phases, with Kagome-like and in-plane chemical ordering, and with incorporation of elements previously not known for MAX phases, including the common Y. We propose the structure to be monoclinic C2/c. As an extension of the work, we suggest a matching set of novel MXenes, from selective etching of the A-element. The demonstrated structural design on simultaneous two-dimensional (2D) and 3D atomic levels expands the property tuning potential of functional materials.

  • 25.
    de las Casas, Charles F.
    et al.
    University of Chicago, IL 60637 USA.
    Christle, David J.
    University of Chicago, IL 60637 USA.
    Ul-Hassan, Jawad
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Ohshima, Takeshi
    National Institute Quantum and Radiol Science and Technology, Japan.
    Nguyen, Son Tien
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Awschalom, David D.
    University of Chicago, IL 60637 USA.
    Stark tuning and electrical charge state control of single divacancies in silicon carbide2017In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 111, no 26, article id 262403Article in journal (Refereed)
    Abstract [en]

    Neutrally charged divacancies in silicon carbide (SiC) are paramagnetic color centers whose long coherence times and near-telecom operating wavelengths make them promising for scalable quantum communication technologies compatible with existing fiber optic networks. However, local strain inhomogeneity can randomly perturb their optical transition frequencies, which degrades the indistinguishability of photons emitted from separate defects and hinders their coupling to optical cavities. Here, we show that electric fields can be used to tune the optical transition frequencies of single neutral divacancy defects in 4H-SiC over a range of several GHz via the DC Stark effect. The same technique can also control the charge state of the defect on microsecond timescales, which we use to stabilize unstable or non-neutral divacancies into their neutral charge state. Using fluorescence-based charge state detection, we show that both 975 nm and 1130 nm excitation can prepare their neutral charge state with near unity efficiency. (C) 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons. org/licenses/by/4.0/).

  • 26.
    del Río, Lía Fernández
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, Faculty of Science & Engineering.
    Optical and Structural Characterization of Natural Nanostructures2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The spectacular biodiversity of our planet is the result of millions of years of evolution. Over this time animals and plants have evolved and adapted to different environments, developing specific behavioral and physical adaptations to increase their chances of survival. During the last centuries human's curiosity has pushed us to study and understand the phenomena and mechanisms of the nature that surrounds us. This understanding has even led to the fields of biomimetics where we seek solutions to human challenges by emulating nature.

    Scarab beetles (from the insect family Scarabaeidae) have fascinated humans for centuries due to the brilliant metallic shine of their chitin-rich exoskeletons and more recently for their ability to polarize reflected light. This doctoral thesis focuses on the optical characterization of the polarized reflected light from beetles in the Chrysina genus, although beetles from other genera also have been investigated. All the Chrysina beetles studied here share one characteristic, they all reflect left-handed near-circular polarized light. In some cases we also detect right-handed polarized light.

    We have observed two different main behaviors among the studied Chrysina beetles. Those which are green-colored scatter the reflected polarized light, whereas those with metallic appearance are broadband specular reflectors. We present a detailed analysis of the optical properties with Mueller-matrix spectroscopic ellipsometry combined with optical- and electron-microscopy studies of the exoskeletons. This allow us to create a model that reproduces the optical properties of these structures. The model consists of a chiral (helicoidal) multilayer structure with a gradual change of the pitch and a constant rotation of the optic axis of the layers.

    Beetles are not alone to have polarizing structures in nature and it is known that many birds and insects have the ability to detect linearly polarized light. This raises the question of whether the polarization properties of the beetles are the direct or indirect results of evolution or just pure coincidence. In order to get a better understanding of the possible reasons of this particular ability, we present a simulation study of different possible scenarios in nature where incoming light could be polarized or unpolarized, and where we consider detectors (eyes) sensitive to different states of polarized light. If the beetles are able to use this characteristic for camouflage, to confuse predators or for intraspecific communication is,

    however, still unknown and requires further investigation.

    My research results provide deeper understanding of the properties of light reflected on the beetle's exoskeleton and the nanostructures responsible for the polarization of the reflected light. The developed model could be used as bioinspiration for the fabrication of novel nano-optical devices. My results can also complement biological behavioral experiments aiming to understand the purposes of this specific optical characteristics in nature.

    List of papers
    1. Polarizing properties and structure of the cuticle of scarab beetles from the Chrysina genus
    Open this publication in new window or tab >>Polarizing properties and structure of the cuticle of scarab beetles from the Chrysina genus
    2016 (English)In: PHYSICAL REVIEW E, ISSN 2470-0045, Vol. 94, no 1, p. 012409-Article in journal (Refereed) Published
    Abstract [en]

    The optical properties of several scarab beetles have been previously studied but few attempts have been made to compare beetles in the same genus. To determine whether there is any relation between specimens of the same genus, we have studied and classified seven species from the Chrysina genus. The polarization properties were analyzed with Mueller-matrix spectroscopic ellipsometry and the structural characteristics with optical microscopy and scanning electron microscopy. Most of the Chrysina beetles are green colored or have a metallic look (gold or silver). The results show that the green-colored beetles polarize reflected light mainly at off-specular angles. The gold-colored beetles polarize light left-handed near circular at specular reflection. The structure of the exoskeleton is a stack of layers that form a cusplike structure in the green beetles whereas the layers are parallel to the surface in the case of the gold-colored beetles. The beetle C. gloriosa is green with gold-colored stripes along the elytras and exhibits both types of effects. The results indicate that Chrysina beetles can be classified according to these two major polarization properties.

    Place, publisher, year, edition, pages
    AMER PHYSICAL SOC, 2016
    National Category
    Mathematical Analysis
    Identifiers
    urn:nbn:se:liu:diva-130835 (URN)10.1103/PhysRevE.94.012409 (DOI)000380116500010 ()
    External cooperation:
    Note

    Funding Agencies|Knut and Alice Wallenberg foundation; Swedish Research Council; Centre in Nano Science and Nano Technology (CeNano) at Linkoping University

    Available from: 2016-08-26 Created: 2016-08-26 Last updated: 2016-11-16
    2. Polarizing properties and structural characteristics of the cuticle of the scarab Beetle Chrysina gloriosa
    Open this publication in new window or tab >>Polarizing properties and structural characteristics of the cuticle of the scarab Beetle Chrysina gloriosa
    2014 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 571, no 3, p. 410-415Article in journal (Refereed) Published
    Abstract [en]

    The scarab beetle Chrysina gloriosa is green with gold-colored stripes along its elytras. The properties of light reflected on these areas are investigated using Mueller-matrix spectroscopic ellipsometry. Both areas reflect light with high degree of left-handed polarization but this effect occurs for specular reflection for the gold-colored areas and for off-specular angles for the green areas. The colors and polarization phenomena originate from reflection of light in the cuticle and a structural analysis is presented to facilitate understanding of the different behaviors of these two areas. Scanning electron microscopy (SEM) images of the cross section of beetle cuticles show a multilayered structure. On the gold-colored areas the layers are parallel to the surface whereas on the green-colored areas they form cusp-like structures. Optical microscopy images show a rather flat surface in the gold-colored areas compared to the green-colored areas which display a net of polygonal cells with star-shaped cavities in the center. Each of the polygons corresponds to one of the cusps observed in the SEM images. Atomic force microscopy images of the star-shaped cavities are also provided. The roughness of the surface and the cusp-like structure of the green-colored areas are considered to cause scattering on this area.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keywords
    Scarab beetle; Near-circular polarization; Mueller-matrix spectroscopic ellipsometry
    National Category
    Atom and Molecular Physics and Optics
    Identifiers
    urn:nbn:se:liu:diva-112885 (URN)10.1016/j.tsf.2013.11.149 (DOI)000346055200013 ()
    Conference
    ICSE-VI International Conference on Spectroscopic Ellipsometry May 2013
    Funder
    Swedish Research CouncilKnut and Alice Wallenberg Foundation
    Available from: 2014-12-18 Created: 2014-12-18 Last updated: 2017-12-05Bibliographically approved
    3. Polarization of light reflected from Chrysina gloriosa under various illuminations
    Open this publication in new window or tab >>Polarization of light reflected from Chrysina gloriosa under various illuminations
    2014 (English)In: Materials Today: Proceedings, Elsevier Ltd , 2014, Vol. 1, p. 172-176Conference paper, Published paper (Refereed)
    Abstract [en]

    When illuminated with unpolarized light, the scarab beetle Chrysina gloriosa, reflects left-handed near-circularly polarized light for a broad range of angles of incidence and wavelengths in the visible. It is, however, known that light scattered from the sky, reflected on water or transmitted through leaves often is linearly polarized. In this study we have analysed the polarization of light reflected on this beetle when illuminated with different polarization states of light. We have also analysed how the response would be with a polarization-sensitive detector. The reflected irradiance is shown to be highest when the incident light is s-polarized or left-handed polarized and the detector is unpolarized (or vice versa). In the case in which both, the source and the detector, are polarized, the irradiance is highest when both are s-polarized. On the contrary the visibility is low when the source is s-polarized and the detector is p-polarized.

    Place, publisher, year, edition, pages
    Elsevier Ltd, 2014
    Series
    Materials Today: Proceedings, ISSN 2214-7853
    Keywords
    Mueller-matrix spectroscopic ellipsometry; Near-circular polarization; Scarab beetle
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-116444 (URN)10.1016/j.matpr.2014.09.020 (DOI)2-s2.0-84923048023 (Scopus ID)
    Conference
    Living Light: Uniting biology and photonics - A memorial meeting in honour of Prof Jean-Pol Vigneron
    Available from: 2015-03-27 Created: 2015-03-26 Last updated: 2016-11-16
    4. Comparison and analysis of Mueller-matrix spectra from exoskeletons of blue, green and red Cetonia aurata
    Open this publication in new window or tab >>Comparison and analysis of Mueller-matrix spectra from exoskeletons of blue, green and red Cetonia aurata
    2014 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 571, p. 739-743Article in journal (Refereed) Published
    Abstract [en]

    The exoskeleton, also called the cuticle, of specimens of the scarab beetle Cetonia aurata is a narrow-band reflector which exhibits metallic shine. Most specimens of C. aurata have a reflectance maximum in the green part of the spectrum but variations from blue–green to red–green are also found. A few specimens are also more distinct blue or red. Furthermore, the reflected light is highly polarized and at near-normal incidence near-circular left-handed polarization is observed. The polarization and color phenomena are caused by a nanostructure in the cuticle. This nanostructure can be modeled as a multilayered twisted biaxial layer from which reflection properties can be calculated. Specifically we calculate the cuticle Mueller matrix which then is fitted to Mueller matrices determined by dual-rotating compensator ellipsometry in the spectral range 400–800 nm at multiple angles of incidence. This non-linear regression analysis provides structural parameters like pitch of the chiral structure as well as layer refractive index data for the different layers in the cuticle. The objective here is to compare spectra measured on C. aurata with different colors and develop a generic structural model. Generally the degree of polarization is large in the spectral region corresponding to the color of the cuticle which for the blue specimen is 400–600 nm whereas for the red specimen it is 530–730 nm. In these spectral ranges, the Mueller-matrix element m41 is non-zero and negative, in particular for small angles of incidence, implicating that the reflected light becomes near-circularly polarizedwith an ellipticity angle in the range 20°–45°.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keywords
    Mueller-matrix ellipsometry; Scarab beetles; Chiral structures; Circular polarization; Natural photonic structures
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-112685 (URN)10.1016/j.tsf.2014.02.012 (DOI)000346055200076 ()
    Conference
    6th International Conference on Spectroscopic Ellipsometry (ICSE-VI), May 26–31, 2013, Kyoto, Japan
    Funder
    Knut and Alice Wallenberg FoundationSwedish Research Council
    Available from: 2014-12-08 Created: 2014-12-08 Last updated: 2017-12-05Bibliographically approved
  • 27.
    Diczfalusy, Elin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology.
    Broberg, Sarah
    Linköping University, Department of Physics, Chemistry and Biology.
    Non-Invasive Methods for Detecting Drug and Alcohol Impaired Drivers: - a Study of Alcohol and Drug Biomarkers and Optical Detection Techniques2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In recent years, the use of alcohol and psychoactive drugs in combination withdriving has recieved increased attention. The lack of in-vehicle devices capable ofdetecting recent drug consumption and the difficulties associated with the breathbasedalcolocks in use today makes it interesting to investigate methods that areable to non-invasivelly measure analytes directly in the blood.

    The assignment of this project, commissioned by Volvo Technology Corporationand Volvo Car Corporation, is to map substances that constitute a possible threatto traffic safety, identify suitable detection markers as a proof of administrationof these substances, and study possible non-invasive techniques to detect thesemarkers. The objective is to present for Volvo if and how to continue evaluatingand developing a non-invasive detection device.

    The project has been carried out by performing an extensive literature study and averification experiment. From the literature review, a number of substances affectingdriving performance could be identified, and a metabolic study was performedfor each drug to map suitable biomarkers. Furthermore, two potential techniquesfor non-invasive detection, near-infrared Raman spectroscopy and near-infraredspectroscopy, were found and evaluated. The experiment was conducted usingnear-infrared Raman spectroscopy, with the aim of investigating the sensitivityand linearity of the method for ethanol detection.

    Based on the theoretical evaluation, both near-infrared Raman spectroscopy andnear-infrared spectroscopy are expected to have potential for non-invasive detectionof ethanol. The experiment further proved the theoretical conclusionsmade for near-infrared Raman spectroscopy. However, neither of the techniquesis thought to have potential for drug detection.Altogether, we believe that non-invasive ethanol detection is possible, but suggestfurther experiments in order to determine which technique to be preferred.

  • 28.
    Dini, Francesca
    et al.
    Department of Electronic Engineering, University of Rome, Italy.
    Magna, Gabriele
    Department of Electronic Engineering, University of Rome, Italy.
    Martinelli, Eugenio
    Department of Electronic Engineering, University of Rome, Italy.
    Pomarico, Giuseppe
    Department of Chemical Science and Technologies, University of Rome, Italy.
    Di Natale, Corrado
    Department of Electronic Engineering, University of Rome, Italy.
    Paolesse, Roberto
    Department of Chemical Science and Technologies, University of Rome, Italy.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Combining porphyrins and pH indicators for analyte detection2015In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 407, no 14, p. 3975-3984Article in journal (Refereed)
    Abstract [en]

    High sensitivity and cross-selectivity are mandatory properties for sensor arrays. Although metalloporphyrins and pH indicators are among the most common and appropriate choices for the preparation of optical sensor arrays, the sensitivity spectrum of these dyes is limited to those analytes able to induce an optical response. To extend the receptive field of optical sensors, we explore the design of composite materials, where the molecular interaction among the subunits enriches their sensing working mechanisms. We demonstrate that blends of single metalloporphyrins and pH indicators, tested with a transduction apparatus based on ubiquitous and easily available hardware, can be endowed with sensing properties wider than those of single constituents, enabling the recognition of a broad range of volatiles.

  • 29.
    Dullin, Christian
    et al.
    University of Medical Centre Goettingen, Germany.
    Larsson, Emanuel
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering. Elettra Sincrotrone Trieste, Italy; University of Trieste, Italy.
    Tromba, Giuliana
    Elettra Sincrotrone Trieste, Italy.
    Markus, Andrea M.
    University of Medical Centre Goettingen, Germany.
    Alves, Frauke
    University of Medical Centre Goettingen, Germany; University of Medical Centre Goettingen, Germany; Max Planck Institute Expt Med, Germany.
    Phase-contrast computed tomography for quantification of structural changes in lungs of asthma mouse models of different severity2015In: Journal of Synchrotron Radiation, ISSN 0909-0495, E-ISSN 1600-5775, Vol. 22, p. 1106-1111Article in journal (Refereed)
    Abstract [en]

    Lung imaging in mouse disease models is crucial for the assessment of the severity of airway disease but remains challenging due to the small size and the high porosity of the organ. Synchrotron inline free-propagation phase-contrast computed tomography (CT) with its intrinsic high soft-tissue contrast provides the necessary sensitivity and spatial resolution to analyse the mouse lung structure in great detail. Here, this technique has been applied in combination with single-distance phase retrieval to quantify alterations of the lung structure in experimental asthma mouse models of different severity. In order to mimic an in vivo situation as close as possible, the lungs were inflated with air at a constant physiological pressure. Entire mice were embedded in agarose gel and imaged using inline free-propagation phase-contrast CT at the SYRMEP beamline (Synchrotron Light Source, Elettra, Trieste, Italy). The quantification of the obtained phase-contrast CT data sets revealed an increasing lung soft-tissue content in mice correlating with the degree of the severity of experimental allergic airways disease. In this way, it was possible to successfully discriminate between healthy controls and mice with either mild or severe allergic airway disease. It is believed that this approach may have the potential to evaluate the efficacy of novel therapeutic strategies that target airway remodelling processes in asthma.

  • 30.
    Ekeroth, Sebastian
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Growth and Characterization of Al1-xInxN Nanospirals2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this work columnar nanospirals of AlInN were grown on top of TiN-coated sapphire substrates by magnetron sputtering. A variety of samples with different growth parameters were fabricated and investigated.

    The main objectives in this work were to optimize the degree of circular polarization and to control the active wavelength region for where this polarization effect occurs. Attempts were made to achieve a high degree of circular polarization in both reflected and transmitted light.

    It is shown that for reflected light it is possible to achieve a high degree of circular polarization within the visible wavelength regions. For transmitted light the concept of achieving circularly polarized light is proven.

  • 31.
    Elofsson, Viktor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanoscale engineering. Linköping University, Faculty of Science & Engineering.
    Almyras, Georgios
    Linköping University, Department of Physics, Chemistry and Biology, Nanoscale engineering. Linköping University, Faculty of Science & Engineering.
    Lü, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Nanoscale engineering. Linköping University, Faculty of Science & Engineering.
    Garbrecht, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Boyd, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Sarakinos, Kostas
    Linköping University, Department of Physics, Chemistry and Biology, Nanoscale engineering. Linköping University, Faculty of Science & Engineering.
    Structure formation in Ag-X (X = Au, Cu) alloys synthesized far-from-equilibrium2018In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 123, no 16Article in journal (Refereed)
    Abstract [en]

    We employ sub-monolayer, pulsed Ag and Au vapor fluxes, along with deterministic growth simulations, and nanoscale probes to study structure formation in miscible Ag-Au films synthesized under far-from-equilibrium conditions. Our results show that nanoscale atomic arrangement is primarily determined by roughness build up at the film growth front, whereby larger roughness leads to increased intermixing between Ag and Au. These findings suggest a different structure formation pathway as compared to the immiscible Ag-Cu system for which the present study, in combination with previously published data, reveals that no significant roughness is developed, and the local atomic structure is predominantly determined by the tendency of Ag and Cu to phase-separate.

  • 32.
    Eriksson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Photoluminescence Characteristics of III-Nitride Quantum Dots and Films2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    III-Nitride semiconductors are very promising in both electronics and optical devices. The ability of the III-Nitride semiconductors as light emitters to span the electromagnetic spectrum from deep ultraviolet light, through the entire visible region, and into the infrared part of the spectrum, is a very important feature, making this material very important in the field of light emitting devices. In fact, the blue emission from Indium Gallium Nitride (InGaN), which was awarded the 2014 Nobel Prize in Physics, is the basis of the common and important white light emitting diode (LED).

    Quantum dots (QDs) have properties that make them very interesting for light emitting devices for a range of different applications, such as the possibility of increasing device efficiency. The spectrally well-defined emission from QDs also allows accurate color reproduction and high-performance communication devices. The small size of QDs, combined with selective area growth allows for an improved display resolution. By control of the polarization direction of QDs, they can be used in more efficient displays as well as in traditional communication devices. The possibility of sending out entangled photon pairs is another QD property of importance for quantum key distribution used for secure communication.

    QDs can hold different exciton complexes, such as the neutral single exciton, consisting of one electron and one hole, and the biexciton, consisting of two excitons. The integrated PL intensity of the biexciton exhibits a quadratic dependence with respect to the excitation power, as compared to the linear power dependence of the neutral single exciton. The lifetime of the neutral exciton is 880 ps, whereas the biexciton, consisting of twice the number of charge carriers and lacks a dark state, has a considerably shorter lifetime of only 500 ps. The ratio of the lifetimes is an indication that the size of the QD is in the order of the exciton Bohr radius of the InGaN crystal making up these QDs in the InGaN QW.

    A large part of the studies of this thesis has been focused on InGaN QDs on top of hexagonal Gallium Nitride (GaN) pyramids, selectively grown by Metal Organic Chemical Vapor Deposition (MOCVD). On top of the GaN pyramids, an InGaN layer and a GaN capping layer were grown. From structural and optical investigations, InGaN QDs have been characterized as growing on (0001) facets on truncated GaN pyramids. These QDs exhibit both narrow photoluminescence linewidths and are linearly polarized in directions following the symmetry of the pyramids.

    In this work, the neutral single exciton, and the more rare negatively charged exciton, have been investigated. At low excitation power, the integrated intensity of the PL peak of the neutral exciton increases linearly with the excitation power. The negatively charged exciton, on the other hand, exhibits a quadratic power dependence, just like that of the biexciton. Upon increasing the temperature, the power dependence of the negatively charged exciton changes to linear, just like the neutral exciton. This change in power dependence is explained in terms of electrons in potential traps close to the QD escaping by thermal excitation, leading to a surplus of electrons in the vicinity of the QD. Consequently, only a single exciton needs to be created by photoexcitation in order to form a negatively charged exciton, while the extra electron is supplied to the QD by thermal excitation.

    Upon a close inspection of the PL of the neutral exciton, a splitting of the peak of just below 0.4 meV is revealed. There is an observed competition in the integrated intensity between these two peaks, similar to that between an exciton and a biexciton. The high energy peak of this split exciton emission is explained in terms of a remotely charged exciton. This exciton state consists of a neutral single exciton in the QD with an extra electron or hole in close vicinity of the QD, which screens the built-in field in the QD.

    The InGaN QDs are very small; estimated to be on the order of the exciton Bohr radius of the InGaN crystal, or even smaller. The lifetimes of the neutral exciton and the negatively charged exciton are approximately 320 ps and 130 ps, respectively. The ratio of the lifetimes supports the claim of the QD size being on the order of the exciton Bohr radius or smaller, as is further supported by power dependence results. Under the assumption of a spherical QD, theoretical calculations predict an emission energy shift of 0.7 meV, for a peak at 3.09 eV, due to the built-in field for a QD with a diameter of 1.3 nm, in agreement with the experimental observations.

    Studying the InGaN QD PL from neutral and charged excitons at elevated temperatures (4 K to 166 K) has revealed that the QDs are surrounded by potential fluctuations that trap charge carriers with an energy of around 20 meV, to be compared with the exciton trapping energy in the QDs of approximately 50 meV. The confinement of electrons close to the QD is predicted to be smaller than for holes, which accounts for the negative charge of the charged exciton, and for the higher probability of capturing free electrons. We have estimated the lifetimes of free electrons and holes in the GaN barrier to be 45 ps and 60 ps, in consistence with excitons forming quickly in the barrier upon photoexcitation and that free electrons and holes get trapped quickly in local potential traps close to the QDs. This analysis also indicates that there is a probability of 35 % to have an electron in the QD between the photoexcitation pulses, in agreement with a lower than quadratic power dependence of the negatively charged exciton.

    InN is an attractive material due to its infrared emission, for applications such as light emitters for communication purposes, but it is more difficult to grow with high quality and low doping concentration as compared to GaN. QDs with a higher In-composition or even pure InN is an interesting prospect as being a route towards increased quantum confinement and room temperature device operation. For all optical devices, p-type doping is needed. Even nominally undoped InN samples tend to be heavily n-type doped, causing problems to make pn-junctions as needed for LEDs. In our work, we present Mg-doped p-type InN films, which when further increasing the Mg-concentration revert to n-type conductivity. We have focused on the effect of the Mg-doping on the light emission properties of these films. The low Mg doped InN film is inhomogeneous and is observed to contain areas with n-type conductivity, so called n-type pockets in the otherwise p-type InN film. A higher concentration of Mg results in a higher crystalline quality and the disappearance of the n-type pockets. The high crystalline quality has enabled us to determine the binding energy of the Mg dopants to 64 meV. Upon further increase of the Mg concentration, the film reverts to ntype conductivity. The highly Mg doped sample also exhibits a red-shifted emission with features that are interpreted as originating from Zinc-Blende inclusions in the Wurtzite InN crystal, acting as quantum wells. The Mg doping is an important factor in controlling the conductivity of InN, as well as its light emission properties, and ultimately construct InN-based devices.

    In summary, in this thesis, both pyramidal InGaN QDs and InGaN QDs in a QW have been investigated. Novel discoveries of exciton complexes in these QD systems have been reported. Knowledge has also been gained about the challenging material InN, including a study of the effect of the Mg-doping concentration on the semiconductor crystalline quality and its light emission properties. The outcome of this thesis enriches the knowledge of the III-Nitride semiconductor community, with the long-term objective to improve the device performance of III-Nitride based light emitting devices.

    List of papers
    1. InGaN quantum dot formation mechanism on hexagonal GaN/InGaN/GaN pyramids
    Open this publication in new window or tab >>InGaN quantum dot formation mechanism on hexagonal GaN/InGaN/GaN pyramids
    Show others...
    2012 (English)In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 23, no 30, p. 305708-Article in journal (Refereed) Published
    Abstract [en]

    Growing InGaN quantum dots (QDs) at the apex of hexagonal GaN pyramids is an elegant approach to achieve a deterministic positioning of QDs. Despite similar synthesis procedures by metal–organic chemical vapor deposition, the optical properties of the QDs reported in the literature vary drastically. The QDs tend to exhibit either narrow or broad emission lines in the micro-photoluminescence spectra. By coupled microstructural and optical investigations, the QDs giving rise to narrow emission lines were concluded to nucleate in association with a (0001) facet at the apex of the GaN pyramid.

    Place, publisher, year, edition, pages
    Institute of Physics (IOP), 2012
    National Category
    Atom and Molecular Physics and Optics
    Identifiers
    urn:nbn:se:liu:diva-79321 (URN)10.1088/0957-4484/23/30/305708 (DOI)000306333500030 ()
    Available from: 2012-07-10 Created: 2012-07-10 Last updated: 2017-12-07Bibliographically approved
    2. Dynamic characteristics of the exciton and the biexciton in a single InGaN quantum dot
    Open this publication in new window or tab >>Dynamic characteristics of the exciton and the biexciton in a single InGaN quantum dot
    Show others...
    2012 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 101, no 6Article in journal (Refereed) Published
    Abstract [en]

    The dynamics of the exciton and the biexciton related emission from a single InGaN quantum dot (QD) have been measured by time-resolved microphotoluminescence spectroscopy. An exciton-biexciton pair of the same QD was identified by the combination of power dependence and polarization-resolved spectroscopy. Moreover, the spectral temperature evolution was utilized in order to distinguish the biexciton from a trion. Both the exciton and the biexciton related emission reveal mono-exponential decays corresponding to time constants of similar to 900 and similar to 500 ps, respectively. The obtained lifetime ratio of similar to 1.8 indicates that the QD is small, with a size comparable to the exciton Bohr radius.

    Place, publisher, year, edition, pages
    American Institute of Physics (AIP), 2012
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-84908 (URN)10.1063/1.4742343 (DOI)000307862400022 ()
    Note

    Funding Agencies|Thaksin University in Thailand||Swedish Research Council (VR)||Swedish Foundation for Strategic Research (SSF)||Knut and Alice Wallenberg Foundation||

    Available from: 2012-10-26 Created: 2012-10-26 Last updated: 2017-12-07
    3. The charged exciton in an InGaN quantum dot on a GaN pyramid
    Open this publication in new window or tab >>The charged exciton in an InGaN quantum dot on a GaN pyramid
    Show others...
    2013 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 103, no 1Article in journal (Refereed) Published
    Abstract [en]

    The emission of a charged exciton in an InGaN quantum dot (QD) on top of a GaN pyramid is identified experimentally. The intensity of the charged exciton exhibits the expected competition with that of the single exciton, as observed in temperature-dependent micro-photoluminescence measurements, performed with different excitation energies. The non-zero charge state of this complex is further supported by time resolved micro-photoluminescence measurements, which excludes neutral alternatives of biexciton. The potential fluctuations in the vicinity of the QD that localizes the charge carriers are proposed to be responsible for the unequal supply of electrons and holes into the QD.

    Place, publisher, year, edition, pages
    American Institute of Physics (AIP), 2013
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-95961 (URN)10.1063/1.4812984 (DOI)000321497200036 ()
    Note

    Funding Agencies|NANO-N consortium||Swedish Foundation for Strategic Research (SSF)||

    Available from: 2013-08-19 Created: 2013-08-12 Last updated: 2017-12-06
  • 33.
    Faber, Felix
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Characterization of attractors in a model for boundary-driven nonlinear optical waveguide arrays with disorder, gain and damping2013Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    The purpose of this thesis is to study the effects of gain and damping on a nonlinear waveguide array with a strong disorder that is driven in the first site, and try to find regimes which have stable stationary solutions. This has been done with a modified DNLS (Discrete nonlinear Schrödinger equation). Stable stationary solutions were mainly found when the damping was stronger than the gain, but some stable stationary regimes were also found when the gain was stronger than the damping.

  • 34.
    Fahleson, Tobias
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Ågren, Hans
    KTH Royal Institute Technology, Sweden.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering. KTH Royal Institute Technology, Sweden.
    A Polarization Propagator for Nonlinear X-ray Spectroscopies2016In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 7, no 11, p. 1991-1995Article in journal (Refereed)
    Abstract [en]

    A complex polarization propagator approach has been developed to third order and implemented in density functional theory (DFT), allowing for the direct calculation of nonlinear molecular properties in the X-ray wavelength regime without explicitly addressing the excited-state manifold. We demonstrate the utility of this propagator method for the modeling of coherent near-edge X-ray two-photon absorption using, as an example, DFT as the underlying electronic structure model. Results are compared with the corresponding near edge X-ray absorption fine structure spectra, illuminating the differences in the role of symmetry, localization, and correlation between the two spectroscopies. The ramifications of this new technique for nonlinear X-ray research are briefly discussed.

  • 35.
    Fernandez del Rio, Lia
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    An Investigation of the Polarization States of Light Reflected from Scarab Beetles of the Chrysina Genus2011Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    The polarization behaviour for six species of Scarab beetles from the Chrysina genus is investigated with Mueller Matrix Spectroscopic Ellipsometer (MMSE). The m41 element of the matrix, which is related to the circular polarization behaviour, is analysed. The ellipticity, degree of polarization and azimuth angle are also presented to get a better understanding of the polarization effect.

    The measurements were done with a dual rotating compensator ellipsometer. The measured wavelength region was from 240 to 1000 nm and the angle of incidence from 25° to 75° in most of the cases.

    In general very high ellipticities (near circular) are reported. All specimens studied reflect both right- and left-handed polarized light. Depending on the species, two general types of polarization behaviour were observed. Chrysina macropus and Chrysina peruviana showed m41 values close to 0. Green stripes on Chrysina gloriosa showed similar polarization behaviour whereas gold stripes on the same beetle had much more pronounced m41 variations. Large m41 variations were also observed for Chrysina argenteola, Chrysina chrysargyrea and Chrysina resplendens. Four specimens of Chrysina resplendens show different m41 patterns suggesting differences in their structures.

  • 36.
    Fernandez Del Rio, Lía
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Järrendahl, Kenneth
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Polarizing properties and structural characteristics of the cuticle of the scarab Beetle Chrysina gloriosa2014In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 571, no 3, p. 410-415Article in journal (Refereed)
    Abstract [en]

    The scarab beetle Chrysina gloriosa is green with gold-colored stripes along its elytras. The properties of light reflected on these areas are investigated using Mueller-matrix spectroscopic ellipsometry. Both areas reflect light with high degree of left-handed polarization but this effect occurs for specular reflection for the gold-colored areas and for off-specular angles for the green areas. The colors and polarization phenomena originate from reflection of light in the cuticle and a structural analysis is presented to facilitate understanding of the different behaviors of these two areas. Scanning electron microscopy (SEM) images of the cross section of beetle cuticles show a multilayered structure. On the gold-colored areas the layers are parallel to the surface whereas on the green-colored areas they form cusp-like structures. Optical microscopy images show a rather flat surface in the gold-colored areas compared to the green-colored areas which display a net of polygonal cells with star-shaped cavities in the center. Each of the polygons corresponds to one of the cusps observed in the SEM images. Atomic force microscopy images of the star-shaped cavities are also provided. The roughness of the surface and the cusp-like structure of the green-colored areas are considered to cause scattering on this area.

  • 37.
    Fernández del Río, Lía
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    An Investigation of the Polarizing Properties and Structural Characteristics in theCuticles of the Scarab Beetles Chrysina gloriosa and Cetonia aurata2012Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Light reflected from the scarab beetles Cetonia aurata (C. aurata) and Chrysina gloriosa (C. gloriosa) has left-handed polarization. In this work the polarizing properties and structural characteristics of the cuticles of these two beetles are investigated with two different techniques: scanning electron microscopy (SEM) and Mueller-matrix spectroscopic ellipsometry (MMSE).

    SEM is used to get cross section images of the epicutucle and the endocuticle. Thicknesses around 18 μm were measured for both layers for C. aurata and between 12 and 16 μm for C. gloriosa. A layered structure is observed in both beetles. In addition, a cusp-like structure is also observed in C. gloriosa.

    MMSE showed left-handed near-circular polarization of light reflected on both beetles. For C. aurata this is observed in a narrow wavelength range (500-600 nm) and for C. gloriosa in a wider wavelength range (400-700 nm) when measured on golden areas of the cuticle. C. gloriosa also has green areas where the reflected light was linearly polarized.

    The results are used in regression modelling. A good model approximation was found for C. aurata for angles up to 60 whereas a good starting point for future work was reached for C. gloriosa.

  • 38.
    Fink, Reinhold F.
    et al.
    Uppsala University.
    Eschner, Annika
    University of Lund.
    Magnuson, Martin
    Uppsala University.
    Björneholm, Olle
    Uppsala University.
    Hjelte, Ingela
    Uppsala University.
    Miron, Catalin
    University of Lund.
    Bässler, Margit
    University of Lund.
    Svensson, Svante
    Uppsala University.
    Novella Piancastelli, Maria
    Uppsala University.
    Sörensen, Stacey L.
    University of Lund.
    Specific production of very long-lived core-excited sulphur atoms by 2p-1s excitation of the OCS molecule followed by ultrafast dissociation2006In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 39, no 12, p. L269-L275Article in journal (Refereed)
    Abstract [en]

    A core-excited sulfur state with a lifetime almost one order of magnitude longer than in molecular 2p core-hole states is selectively produced by ultrafast dissociation of S 2p → σ* excited OCS. Clear evidence for this is provided by strong atomic peaks (20% of the total intensity) in x-ray fluorescence but very weak ones (2%) in the corresponding resonant Auger spectrum. Corroborating the assignment of the spectra, ab initio calculations explain the enhanced lifetime: the Auger decay of the produced 3D3 (2p53p5) sulfur state is strongly decreased as it contradicts a newly derived propensity rule of the L2,3MM Auger decay.

  • 39.
    Fransson, Thomas
    Linköping University, Department of Physics, Chemistry and Biology.
    Chemical bond analysis in the ten-electron series2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis presents briefly the application of quantum mechanics on systems ofchemical interest, i.e., the field of quantum chemistry and computational chemistry.The molecules of the ten-electron series, hydrogen fluoride, water, ammonia,methane and neon, are taken as computational examples. Some applications ofquantum chemistry are then shown on these systems, with emphasis on the natureof the molecular bonds. Conceptual methods of chemistry and theoreticalchemistry for these systems are shown to be valid with some restrictions, as theseinterpretations does not represent physically measurable entities.The orbitals and orbital energies of neon is studied, the binding van der Waalsinteractionresulting in a Ne2 molecule is studied with a theoretical bond lengthof 3.23 °A and dissociation energy of 81.75 μEh. The equilibrium geometries ofFH, H2O, NH3 and CH4 are studied and the strength and character of the bondsinvolved evaluated using bond order, dipole moment, Mulliken population analysisand L¨owdin population analysis. The concept of electronegativity is studied in thecontext of electron transfer. Lastly, the barrier of inversion for NH3 is studied, withan obtained barrier height of 8.46 mEh and relatively constant electron transfer.

  • 40.
    Fransson, Thomas
    Linköping University, Department of Physics, Chemistry and Biology.
    X-ray absorption spectroscopy by means of Lanczos-chain driven damped coupled cluster response theory2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A novel method by which to calculate the near edge X-rayabsorption fine structure region of the X-ray absorption spectrum has been derived and implemented. By means of damped coupled cluster theory at coupled cluster levels CCS, CC2, CCSD and CCSDR(3), the spectra of neon and methane have been investigated. Using methods incorprating double excitations, the important relaxation effects maybe taken into account by simultaneous excitation of the core electron and relaxation of other electrons. An asymmetric Lanczos-chain driven approach has been utilized as a means to partially resolve the excitation space given by the coupled cluster Jacobian. The K-edge of the systems have been considered, and relativistic effects are estimated with use of the Douglas--Kroll scalar relativistic Hamiltonian. Comparisons have been made to results obtained with the four-component static-exchange approach and ionization potentials obtained by the {Delta}SCF-method.

    The appropriate basis sets by which to describe the core and excited states have been been determined.  The addition of core-polarizing functions and diffuse or Rydberg functions is important for this description. Scalar relativistic effects accounts for an increase in excitation energies due to the contraction of the 1s-orbital, and this increase is seen to be 0.88 eV for neon. The coupled cluster hierachy shows a trend of convergence towards the experimental spectrum, with an 1s -> 3p excitation energy for neon of an accuracy of 0.40 eV at a relativistic CCSDR(3) level of theory. Results obtained at the damped coupled cluster and STEX levels of theory, respectively, are seen to be in agreement, with a mere relative energy shift.

  • 41.
    Fransson, Thomas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Harada, Yoshihisa
    University of Tokyo, Japan.
    Kosugi, Nobuhiro
    Institute Molecular Science, Japan.
    Besley, Nicholas A.
    University of Nottingham, England.
    Winter, Bernd
    Helmholtz Centre Berlin, Germany.
    Rehr, John J.
    University of Washington, WA 98195 USA.
    Pettersson, Lars G. M.
    Stockholm University, Sweden.
    Nilsson, Anders
    Stockholm University, Sweden.
    X-ray and Electron Spectroscopy of Water2016In: Chemical Reviews, ISSN 0009-2665, E-ISSN 1520-6890, Vol. 116, no 13, p. 7551-7569Article, review/survey (Refereed)
    Abstract [en]

    Here we present an overview of recent developments of X-ray and electron spectroscopy to probe water at different temperatures. Photon-induced ionization followed by detection of electrons from either the 0 is level or the valence band is the basis of photoelectron spectroscopy. Excitation between the 0 is and the unoccupied states or occupied states is utilized in X-ray absorption and X-ray emission spectroscopies. These techniques probe the electronic structure of the liquid phase and show sensitivity to the local hydrogen-bonding structure. Both experimental aspects related to the measurements and theoretical simulations to assist in the interpretation are discussed in detail. Different model systems are presented such as the different bulk phases of ice and various adsorbed monolayer structures on metal surfaces.

  • 42.
    Fullagar, Wilfred K.
    et al.
    Lund University, Sweden; Australian National University, Australia.
    Uhlig, Jens
    Lund University, Sweden.
    Mandal, Ujjwal
    Lund University, Sweden; University of Burdwan, India.
    Kurunthu, Dharmalingam
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Lund University, Sweden.
    El Nahhas, Amal
    Lund University, Sweden.
    Tatsuno, Hideyuki
    Lund University, Sweden.
    Honarfar, Alireza
    Lund University, Sweden.
    Parnefjord Gustafsson, Fredrik
    Lund University, Sweden.
    Sundstrom, Villy
    Lund University, Sweden.
    Palosaari, Mikko R. J.
    University of Jyvaskyla, Finland.
    Kinnunen, Kimmo M.
    University of Jyvaskyla, Finland.
    Maasilta, Ilari J.
    University of Jyvaskyla, Finland.
    Miaja-Avila, Luis
    NIST, CO 80305 USA.
    ONeil, Galen C.
    NIST, CO 80305 USA.
    Il Joe, Young
    NIST, CO 80305 USA.
    Swetz, Daniel S.
    NIST, CO 80305 USA.
    Ullom, Joel N.
    NIST, CO 80305 USA.
    Beating Darwin-Bragg losses in lab-based ultrafast x-ray experiments2017In: STRUCTURAL DYNAMICS, ISSN 2329-7778, Vol. 4, no 4, article id 044011Article in journal (Refereed)
    Abstract [en]

    The use of low temperature thermal detectors for avoiding Darwin-Bragg losses in lab-based ultrafast experiments has begun. An outline of the background of this new development is offered, showing the relevant history and initiative taken by this work. (C) 2017 Author(s).

  • 43.
    Fullager, Daniel B.
    et al.
    University of North Carolina Charlotte, NC 28223 USA.
    Boreman, Glenn D.
    University of North Carolina Charlotte, NC 28223 USA.
    Hofmann, Tino
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. University of North Carolina Charlotte, NC 28223 USA.
    Infrared dielectric response of nanoscribe IP-dip and IP-L monomers after polymerization from 250 cm(-1) to 6000 cm(-1)2017In: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 7, no 3, p. 888-894Article in journal (Refereed)
    Abstract [en]

    Direct laser writing via two photon polymerization has enabled previously unavailable degrees of freedom in the additive fabrication of micro-to-meso scale structures. The structures produced by these techniques are ideally suited to create optical devices which operate from the THz regime to the near infrared spectrum into the visible spectral range. Here we report on the infrared dielectric response of two monomers IP-dip and IP-L after polymerization which are frequently employed in commercial two photon lithography tools from nanoscribe over the spectral range of 250 cm(-1) to 6000 cm(-1). A parameterized dielectric function model is presented and discussed. (C) 2017 Optical Society of America

  • 44.
    Giustina, M.
    et al.
    Austrian Academic Science, Austria; University of Vienna, Austria.
    Versteegh, M. A. M.
    Austrian Academic Science, Austria; University of Vienna, Austria.
    Wengerowsky, S.
    Austrian Academic Science, Austria; University of Vienna, Austria.
    Handsteiner, J.
    Austrian Academic Science, Austria; University of Vienna, Austria.
    Hochrainer, A.
    Austrian Academic Science, Austria; University of Vienna, Austria.
    Phelan, K.
    Austrian Academic Science, Austria.
    Steinlechner, F.
    Austrian Academic Science, Austria.
    Kofler, J.
    Max Planck Institute Quantum Opt MPQ, Germany.
    Larsson, Jan-Åke
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Abellan, C.
    Barcelona Institute Science and Technology, Spain; ICREA, Spain.
    Amaya, W.
    Barcelona Institute Science and Technology, Spain; ICREA, Spain.
    Pruneri, V.
    Barcelona Institute Science and Technology, Spain; ICREA, Spain.
    Mitchell, M. W. M.
    Barcelona Institute Science and Technology, Spain; ICREA, Spain.
    Beyer, J.
    Phys Technical Bundesanstalt, Germany.
    Gerrits, T.
    NIST, CO 80305 USA.
    Lita, A.
    NIST, CO 80305 USA.
    Shalm, L. K.
    NIST, CO 80305 USA.
    Nam, S. W.
    NIST, CO 80305 USA.
    Scheidl, T.
    Austrian Academic Science, Austria; University of Vienna, Austria.
    Ursin, R.
    Austrian Academic Science, Austria.
    Wittmann, B.
    Austrian Academic Science, Austria; University of Vienna, Austria.
    Zeilinger, A.
    Austrian Academic Science, Austria; University of Vienna, Austria.
    Significant-Loophole-Free Test of Local Realism with Entangled Photons2016In: 2016 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE , 2016Conference paper (Refereed)
    Abstract [en]

    We report an experimental violation of a Bell inequality with strong statistical significance. Our experiment employs polarization measurements on entangled single photons and closes the locality, freedom-of-choice, fair-sampling, coincidence-time, and memory loopholes simultaneously.

  • 45.
    Gomez, E. S.
    et al.
    Univ Concepcion, Chile.
    Riquelme, P.
    Univ Concepcion, Chile.
    Solis-Prosser, M. A.
    Univ Concepcion, Chile.
    Gonzalez, P.
    Univ Concepcion, Chile.
    Ortega, E.
    Univ Concepcion, Chile; Austrian Acad Sci, Austria.
    Xavier, Guilherme B
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering. Univ Concepcion, Chile.
    Lima, G.
    Univ Concepcion, Chile; Univ Concepcion, Chile.
    Tunable entanglement distillation of spatially correlated down-converted photons2018In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 26, no 11, p. 13961-13972Article in journal (Refereed)
    Abstract [en]

    We report on a new technique for entanglement distillation of the bipartite continuous variable state of spatially correlated photons generated in the spontaneous parametric down-conversion process ( SPDC), where tunable non-Gaussian operations are implemented and the post-processed entanglement is certified in real-time using a single-photon sensitive electron multiplying CCD (EMCCD) camera. The local operations are performed using non-Gaussian filters modulated into a programmable spatial light modulator and, by using the EMCCD camera for actively recording the probability distributions of the twin-photons, one has fine control of the Schmidt number of the distilled state. We show that even simple non-Gaussian filters can be finely tuned to a similar to 67% net gain of the initial entanglement generated in the SPDC process. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

  • 46.
    Greczynski, Grzegorz
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Zhirkov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Petrov, Ivan
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. University of Illinois, IL 61801 USA; University of Illinois, IL 61801 USA.
    Greene, Joseph E
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. University of Illinois, IL 61801 USA; University of Illinois, IL 61801 USA; University of Illinois, IL 61801 USA.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Control of the metal/gas ion ratio incident at the substrate plane during high-power impulse magnetron sputtering of transition metals in Ar2017In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 642, p. 36-40Article in journal (Refereed)
    Abstract [en]

    High-power impulse magnetron sputtering (HiPIMS) of materials systems with metal/gas-atom mass ratios m(Me)/m(g) near, or less than, unity presents a challenge for precise timing of synchronous substrate-bias pulses to select metal-ion irradiation of the film and, thus, reduce stress while increasing layer density during low-temperature growth. The problem stems from high gas-ion fluxes Fg+(t) at the substrate, which overlap with metal-ion fluxes FMe+(t). We use energy-and time-dependent mass spectrometry to analyze FMe+(t) and Fg+(t) for Group IVb transition-metal targets in Ar and show that the time-and energy-integrated metal/gas ion ratio NMe+/NAr+ at the substrate can be controlled over a wide range by adjusting the HiPIMS pulse length tau(ON), while maintaining the peak target current density J(T,peak) constant. The effect is a consequence of severe gas rarefaction which scales with J(T)(t). For Ti-HiPIMS, terminating the discharge at the maximum J(T)(t), corresponding to tau(ON) = 30 mu s, there is an essentially complete loss of Ar+ ion intensity, yielding NTi+/NAr+ similar to 60. With increasing tau(ON),J(T)(t) decreases and NTi+/NAr+ gradually decays, due to Ar refill, to similar to 1 with tau(ON) = 120 s. Time-resolved ion-energy distribution functions confirm that the degree of rarefaction depends on tau(ON): for shorter pulses, tau ONHTC/SUBTAG amp;lt; FORTITLEHTC_RETAIN 60 [rs, the original sputtered-atom Sigmund-Thompson energy distributions are preserved long after the HiPIMS pulse, which is in distinct contrast to longer pulses, tau(ON) amp;gt;= 60 mu s, for which the energy distributions collapse into narrow ther-malized peaks. Thus, optimizing the HiPIMS pulse width minimizes the gas-ion flux to the substrate independent of m(Me)/m(g).

    The full text will be freely available from 2019-09-14 16:21
  • 47.
    Greiner, Franko
    et al.
    Christian Albrechts Univ Kiel, Germany.
    Melzer, Andre
    Ernst Moritz Arndt Univ Greifswald, Germany.
    Tadsen, Benjamin
    Christian Albrechts Univ Kiel, Germany.
    Groth, Sebastian
    Christian Albrechts Univ Kiel, Germany.
    Killer, Carsten
    EURATOM, Germany.
    Kirchschlager, Florian
    Christian Albrechts Univ Kiel, Germany; UCL, England.
    Wieben, Frank
    Christian Albrechts Univ Kiel, Germany.
    Pilch, Iris
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Krueger, Harald
    Ernst Moritz Arndt Univ Greifswald, Germany.
    Block, Dietmar
    Christian Albrechts Univ Kiel, Germany.
    Piel, Alexander
    Christian Albrechts Univ Kiel, Germany.
    Wolf, Sebastian
    Christian Albrechts Univ Kiel, Germany.
    Diagnostics and characterization of nanodust and nanodusty plasmas2018In: European Physical Journal D: Atomic, Molecular and Optical Physics, ISSN 1434-6060, E-ISSN 1434-6079, Vol. 72, no 5, article id 81Article in journal (Refereed)
    Abstract [en]

    Plasmas growing or containing nanometric dust particles are widely used and proposed in plasma technological applications for production of nano-crystals and surface deposition. Here, we give a compact review of in situ methods for the diagnostics of nanodust and nanodusty plasmas, which have been developed in the framework of the SFB-TR24 to fully characterize these systems. The methods include kinetic Mie ellipsometry, angular-resolved Mie scattering, and 2D imaging Mie ellipsometry to get information about particle growth processes, particle sizes and particle size distributions. There, also the role of multiple scattering events is analyzed using radiative transfer simulations. Computed tomography and Abel inversion techniques to get the 3D dust density profiles of the particle cloud will be presented. Diagnostics of the dust dynamics yields fundamental dust and plasma properties like particle charges and electron and ion densities. Since nanodusty plasmas usually form dense dust clouds electron depletion (Haynes effect) is found to be significant.

  • 48.
    Gubaydullin, A. R.
    et al.
    ITMO Univ, Russia; Univ Claude Bernard Lyon 1, France.
    Morozov, K. M.
    St Petersburg Acad Univ, Russia.
    Ivanov, K. A.
    ITMO Univ, Russia.
    Symonds, C.
    Univ Claude Bernard Lyon 1, France.
    Bellessa, J.
    Univ Claude Bernard Lyon 1, France.
    Monkman, A. P.
    Univ Durham, England.
    Kaliteevski, M. A.
    ITMO Univ, Russia; St Petersburg Acad Univ, Russia; Russian Acad Sci, Russia.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Control of spontaneous emission rate in Tamm plasmon structures2018In: 2018 INTERNATIONAL CONFERENCE LASER OPTICS (ICLO 2018), IEEE , 2018, p. 131-131Conference paper (Refereed)
    Abstract [en]

    We have studied experimentally and theoretically spontaneous emission rate modification in Tamm plasmon structures with semiconductor( InAs/GaAs quantum dots) and organic (CBP) emitters. Time-resolved spectroscopy demonstrates that spontaneous emission rate is increased by one order in magnitude. Experimentally measured spontaneous emission pattern coincides with calculated dependence of modal Purcel factor on frequency and angle of emission.

  • 49.
    Gunnarsson, Rickard
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Brenning, Nils
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering. KTH Royal Inst Technol, Sweden.
    Ojamäe, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Kalered, Emil
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Raadu, Michael Allan
    KTH Royal Inst Technol, Sweden.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Nucleation of titanium nanoparticles in an oxygen-starved environment. II: theory2018In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 51, no 45, article id 455202Article in journal (Refereed)
    Abstract [en]

    The nucleation and growth of pure titanium nanoparticles in a low-pressure sputter plasma has been believed to be essentially impossible. The addition of impurities, such as oxygen or water, facilitates this and allows the growth of nanoparticles. However, it seems that this route requires such high oxygen densities that metallic nanoparticles in the hexagonal alpha Ti-phase cannot be synthesized. Here we present a model which explains results for the nucleation and growth of titanium nanoparticles in the absent of reactive impurities. In these experiments, a high partial pressure of helium gas was added which increased the cooling rate of the process gas in the region where nucleation occurred. This is important for two reasons. First, a reduced gas temperature enhances Ti-2 dimer formation mainly because a lower gas temperature gives a higher gas density, which reduces the dilution of the Ti vapor through diffusion. The same effect can be achieved by increasing the gas pressure. Second, a reduced gas temperature has a more than exponential effect in lowering the rate of atom evaporation from the nanoparticles during their growth from a dimer to size where they are thermodynamically stable, r*. We show that this early stage evaporation is not possible to model as a thermodynamical equilibrium. Instead, the single-event nature of the evaporation process has to be considered. This leads, counter intuitively, to an evaporation probability from nanoparticles that is exactly zero below a critical nanoparticle temperature that is size-dependent. Together, the mechanisms described above explain two experimentally found limits for nucleation in an oxygen-free environment. First, there is a lower limit to the pressure for dimer formation. Second, there is an upper limit to the gas temperature above which evaporation makes the further growth to stable nuclei impossible.

  • 50.
    Guo, Yiting
    et al.
    Chinese Acad Sci, Peoples R China; Univ Chinese Acad Sci, Peoples R China.
    Liu, Yanfeng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Zhu, Qinglian
    Xi An Jiao Tong Univ, Peoples R China.
    Li, Cheng
    Chinese Acad Sci, Peoples R China.
    Jin, Yingzhi
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Puttisong, Yuttapoom
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Liu, Feng
    Hebei Univ, Peoples R China.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ma, Wei
    Xi An Jiao Tong Univ, Peoples R China.
    Li, Weiwei
    Chinese Acad Sci, Peoples R China.
    Effect of Side Groups on the Photovoltaic Performance Based on Porphyrin-Perylene Bisimide Electron Acceptors2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 38, p. 32454-32461Article in journal (Refereed)
    Abstract [en]

    In this work, we developed four porphyrin-based small molecular electron acceptors for non-fullerene organic solar cells, in which different side groups attached to the porphyrin core were selected in order to achieve optimized performance. The molecules contain porphyrin as the core, perylene bisimides as end groups, and the ethynyl unit as the linker. Four side groups, from 2,6-di(dodecyloxy)phenyl to (2-ethylhexyl)thiophen-2-yl, pentadecan-7-yl, and 3,5-di(dodecyloxy)phenyl unit, were applied into the electron acceptors. The new molecules exhibit broad absorption spectra from 300 to 900 nm and high molar extinction coefficients. The molecules as electron acceptors were applied into organic solar cells, showing increased power conversion efficiencies from 1.84 to 5.34%. We employed several techniques, including photoluminescence spectra, electroluminescence spectra, atomic force microscopy, and grazing-incidence wide-angle X-ray to probe the blends to find the effects of the side groups on the photovoltaic properties. We found that the electron acceptors with 2,6-di(dodecyloxy)phenyl units show high-lying frontier energy levels, good crystalline properties, and low nonradiative recombination loss, resulting in possible large phase separation and low energy loss, which is responsible for the low performance. Our results provide a detailed study about the side groups of non-fullerene materials, demonstrating that porphyrin can be used to design electron acceptors toward near-infrared absorption.

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