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  • 101.
    Cranston, Emily D
    et al.
    Royal Institute of Technology.
    Eita, Mohamed
    Royal Institute of Technology.
    Johansson, Erik
    Royal Institute of Technology.
    Netrval, Julia
    Bruker AXS Nord AB.
    Salajkova, Michaela
    Royal Institute of Technology.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Wagberg, Lars
    Royal Institute of Technology.
    Determination of Youngs Modulus for Nanofibrillated Cellulose Multilayer Thin Films Using Buckling Mechanics2011Inngår i: BIOMACROMOLECULES, ISSN 1525-7797, Vol. 12, nr 4, s. 961-969Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Youngs modulus of multilayer films containing nanofibrillated cellulose (NFC) and polyethyleneimine (PEI) was determined Using the strain-induced elastic buckling instability for mechanical measurements (SLEBIMM) technique.(1) Multilayer films were built up on polydimethylsiloxane substrates using electrostatic layer-by-layer assembly. At 50% relative humidity, SIEBIMM gave a constant Youngs modulus of 1.5 +/- 0.2 GPa for 35-75 run thick films. Conversely, in vacuum, the Youngs modulus was 10 times larger, at 17.2 +/- 1.2 GPa. A slight decrease in buckling wavelength with increasing strain was observed by scanning electron microscopy with in situ compression, and above 10% strain, extensive cracking parallel to the compressive direction occurred. We conclude that whereas PEI acts as a "glue" to hold multiple layers of NFC together, it prevents full development of hydrogen bonding and specific fibril-fibril interactions, and at high humidity, its hygroscopic nature decreases the elastic modulus when compared with pure NFC films.

  • 102.
    Darakchieva, V.
    et al.
    IFM Linköpings universitet.
    Paskov, Plamen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Schubert, Mattias
    Fakultät für Physik und Geowissenshaften Universität Leipzig.
    Paskova, Tanja
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Amano, H.
    Dept of Electrical and Electronic Engineering Meijo University, Japan.
    Akasaki, I.
    Dept. of Electrical and Electronic Engineering Meijo University, Japan.
    Strain evolution and phonons in AlN/GaN superlattices2003Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    AlN/GaN superlattices (SLs) with different periods grown on GaN buffer layers were studied by infrared spectroscopic ellipsometry (IRSE), Raman scattering (RS) and high-resolution reciprocal space mapping (RSM). The lattice parameters and the degree of strain in the GaN buffer and the SL constituents were determined. Phonon modes originating from the buffer layer and the SL sublayers were identified and their frequency shifts were correlated with the strain state of the films.

  • 103.
    Darakchieva, Vanya
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Paskova, T.
    Institute of Solid State Physics, University of Bremen, 28359 Bremen, Germany.
    Schubert, M.
    Department of Electrical Engineering, University of Nebraska, Lincoln, NE 68588, United States.
    Paskov, Plamen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Hommel, D.
    Institute of Solid State Physics, University of Bremen, 28359 Bremen, Germany.
    Heuken, M.
    Aixtron AG, D-52072 Aachen, Germany.
    Off, J.
    Institute of Physics 4, University of Stuttgart, 70569 Stuttgart, Germany.
    Haskell, B.A.
    Materials Department, University of California, Santa Barbara, CA 93106, United States.
    Fini, P.T.
    Materials Department, University of California, Santa Barbara, CA 93106, United States.
    Speck, J.S.
    Materials Department, University of California, Santa Barbara, CA 93106, United States.
    Nakamura, S.
    Materials Department, University of California, Santa Barbara, CA 93106, United States.
    Effect of anisotropic strain on phonons in a-plane and c-plane GaN layers2007Inngår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 300, nr 1, s. 233-238Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have studied phonons in two types of anisotropically strained GaN films: c-plane GaN films grown on a-plane sapphire and a-plane GaN films grown on r-plane sapphire. The anisotropic strain in the films is determined by high-resolution X-ray diffraction (HRXRD) in different measuring geometries and the phonon parameters have been assessed by generalized infrared spectroscopic ellipsometry (GIRSE). The effect of strain anisotropy on GaN phonon frequencies is presented and the phonon deformation potentials aA1 (TO), bA1 (TO), cE1 (TO) and cE1 (LO) are determined. © 2006 Elsevier B.V. All rights reserved.

  • 104.
    Darakchieva, Vanya
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Paskova, Tanja
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Paskov, Plamen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Schubert, M
    Monemar, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Figge, S
    Hommel, D
    Haskell, BA
    Fini, PT
    Nakamura, S
    Assessment of phonon mode characteristics via infrared spectroscopic ellipsometry on a-plane GaN2006Inngår i: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 243, nr 7, s. 1594-1598Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Generalized infrared spectroscopic ellipsometry was applied to study the vibrational properties of anisotropically strained a-plane GaN films with different thicknesses. We have established a correlation between the phonon mode parameters and the strain, which allows the determination of the deformation potentials and strain-free frequency of the GaN A,(TO) mode. These results are compared with previous theoretical and experimental findings and discussed.

  • 105.
    Darakchieva, Vanya
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Paskova, Tanja
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Schubert, M.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Paskov, Plamen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hommel, D.
    Off, J.
    Scholz, F.
    Heuken, M.
    Haskell, B.A.
    Fini, P.T.
    Speck, S.J.
    Nakamura, S.
    Anisotropic strain and phonon deformation potentials in GaN2007Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 75, nr 19, s. 195217-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report optical phonon frequency studies in anisotropically strained c -plane- and a -plane-oriented GaN films by generalized infrared spectroscopic ellipsometry and Raman scattering spectroscopy. The anisotropic strain in the films is obtained from high-resolution x-ray diffraction measurements. Experimental evidence for splitting of the GaN E1 (TO), E1 (LO), and E2 phonons under anisotropic strain in the basal plane is presented, and their phonon deformation potentials c E1 (TO), c E1 (LO), and c E2 are determined. A distinct correlation between anisotropic strain and the A1 (TO) and E1 (LO) frequencies of a -plane GaN films reveals the a A1 (TO), b A1 (TO), a E1 (LO), and b E1 (LO) phonon deformation potentials. The a A1 (TO) and b A1 (TO) are found to be in very good agreement with previous results from Raman experiments. Our a A1 (TO) and a E1 (LO) phonon deformation potentials agree well with recently reported theoretical estimations, while b A1 (TO) and b E1 (LO) are found to be significantly larger than the theoretical values. A discussion of the observed differences is presented. © 2007 The American Physical Society.

  • 106.
    del Río, Lía Fernández
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska fakulteten.
    Optical and Structural Characterization of Natural Nanostructures2016Doktoravhandling, med artikler (Annet vitenskapelig)
    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.

    Delarbeid
    1. Polarizing properties and structure of the cuticle of scarab beetles from the Chrysina genus
    Åpne denne publikasjonen i ny fane eller vindu >>Polarizing properties and structure of the cuticle of scarab beetles from the Chrysina genus
    2016 (engelsk)Inngår i: PHYSICAL REVIEW E, ISSN 2470-0045, Vol. 94, nr 1, s. 012409-Artikkel i tidsskrift (Fagfellevurdert) 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.

    sted, utgiver, år, opplag, sider
    AMER PHYSICAL SOC, 2016
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-130835 (URN)10.1103/PhysRevE.94.012409 (DOI)000380116500010 ()
    Eksternt samarbeid:
    Merknad

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

    Tilgjengelig fra: 2016-08-26 Laget: 2016-08-26 Sist oppdatert: 2016-11-16
    2. Polarizing properties and structural characteristics of the cuticle of the scarab Beetle Chrysina gloriosa
    Åpne denne publikasjonen i ny fane eller vindu >>Polarizing properties and structural characteristics of the cuticle of the scarab Beetle Chrysina gloriosa
    2014 (engelsk)Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 571, nr 3, s. 410-415Artikkel i tidsskrift (Fagfellevurdert) 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.

    sted, utgiver, år, opplag, sider
    Elsevier, 2014
    Emneord
    Scarab beetle; Near-circular polarization; Mueller-matrix spectroscopic ellipsometry
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-112885 (URN)10.1016/j.tsf.2013.11.149 (DOI)000346055200013 ()
    Konferanse
    ICSE-VI International Conference on Spectroscopic Ellipsometry May 2013
    Forskningsfinansiär
    Swedish Research CouncilKnut and Alice Wallenberg Foundation
    Tilgjengelig fra: 2014-12-18 Laget: 2014-12-18 Sist oppdatert: 2017-12-05bibliografisk kontrollert
    3. Polarization of light reflected from Chrysina gloriosa under various illuminations
    Åpne denne publikasjonen i ny fane eller vindu >>Polarization of light reflected from Chrysina gloriosa under various illuminations
    2014 (engelsk)Inngår i: Materials Today: Proceedings, Elsevier Ltd , 2014, Vol. 1, s. 172-176Konferansepaper, Publicerat paper (Fagfellevurdert)
    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.

    sted, utgiver, år, opplag, sider
    Elsevier Ltd, 2014
    Serie
    Materials Today: Proceedings, ISSN 2214-7853
    Emneord
    Mueller-matrix spectroscopic ellipsometry; Near-circular polarization; Scarab beetle
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-116444 (URN)10.1016/j.matpr.2014.09.020 (DOI)2-s2.0-84923048023 (Scopus ID)
    Konferanse
    Living Light: Uniting biology and photonics - A memorial meeting in honour of Prof Jean-Pol Vigneron
    Tilgjengelig fra: 2015-03-27 Laget: 2015-03-26 Sist oppdatert: 2016-11-16
    4. Comparison and analysis of Mueller-matrix spectra from exoskeletons of blue, green and red Cetonia aurata
    Åpne denne publikasjonen i ny fane eller vindu >>Comparison and analysis of Mueller-matrix spectra from exoskeletons of blue, green and red Cetonia aurata
    2014 (engelsk)Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 571, s. 739-743Artikkel i tidsskrift (Fagfellevurdert) 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°.

    sted, utgiver, år, opplag, sider
    Elsevier, 2014
    Emneord
    Mueller-matrix ellipsometry; Scarab beetles; Chiral structures; Circular polarization; Natural photonic structures
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-112685 (URN)10.1016/j.tsf.2014.02.012 (DOI)000346055200076 ()
    Konferanse
    6th International Conference on Spectroscopic Ellipsometry (ICSE-VI), May 26–31, 2013, Kyoto, Japan
    Forskningsfinansiär
    Knut and Alice Wallenberg FoundationSwedish Research Council
    Tilgjengelig fra: 2014-12-08 Laget: 2014-12-08 Sist oppdatert: 2017-12-05bibliografisk kontrollert
  • 107.
    Eita, Mohamed
    et al.
    Royal Institute Technology KTH.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Granberg, Hjalmar
    Innventia AB.
    Wagberg, Lars
    Royal Institute Technology KTH.
    Addition of silica nanoparticles to tailor the mechanical properties of nanofibrillated cellulose thin films2011Inngår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 363, nr 2, s. 566-572Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Over the last decade, the use of nanocellulose in advanced technological applications has been promoted both due the excellent properties of this material in combination with its renewability. In this study, multilayered thin films composed of nanofibrillated cellulose (NFC), polyvinyl amine (PVAm) and silica nanoparticles were fabricated on polydimethylsiloxane (PDMS) using a layer-by-layer adsorption technique. The multilayer build-up was followed in situ by quartz crystal microbalance with dissipation, which indicated that the PVAm-SiO(2)-PVAm-NFC system adsorbs twice as much wet mass material compared to the PVAm-NFC system for the same number of bilayers. This is accompanied with a higher viscoelasticity for the PVAm-SiO(2)-PVAm-NFC system. Ellipsometry indicated a dry-state thickness of 2.2 and 3.4 nm per bilayer for the PVAm-NFC system and the PVAm-SiO(2)-PVAm-NFC system, respectively. Atomic force microscopy height images indicate that in both systems, a porous network structure is achieved. Youngs modulus of these thin films was determined by the Strain-Induced Elastic Buckling Instability for Mechanical Measurements (SIEBIMM) technique. The Youngs modulus of the PVAm/NFC films was doubled, from 1 to 2 GPa, upon incorporation of silica nanoparticles in the films. The introduction of the silica nanoparticles lowered the refractive index of the films, most probably due to an increased porosity of the films.

  • 108.
    Ekeroth, Sebastian
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Growth and Characterization of Al1-xInxN Nanospirals2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    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.

  • 109. Engstrom, C.
    et al.
    Berlind, Torun
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Birch, Jens
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Ivanov, I.P.
    Cypress Semiconductor Corporation, 2401 East 86th Street, Bloomington, MN 55425, United States.
    Kirkpatrick, S.R.
    Department of Mechanical Engineering, Center for Mat. Res. and Analysis, University of Nebraska-Lincoln, 255 WSEC, Lincoln, NE 68588-0656, United States.
    Rohde, S.
    Department of Mechanical Engineering, Center for Mat. Res. and Analysis, University of Nebraska-Lincoln, 255 WSEC, Lincoln, NE 68588-0656, United States.
    Design, plasma studies, and ion assisted thin film growth in an unbalanced dual target magnetron sputtering system with a solenoid coil2000Inngår i: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 56, nr 2, s. 107-113Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An original design and solution to the problem of magnetic field interactions in a vacuum chamber between two unbalanced magnetron sputtering sources and a solenoid coil serving to increase plasma density in near substrate position, is presented. By changing the solenoid coil current strength and direction, plasma growth conditions in an argon discharge and Ti-magnetron cathodes were found to vary in a broad region. Langmuir probe analysis shows that an increase in the coil current from 0 to 6 A caused plasma and substrate floating potentials to change from -7 to -30 V and from +1 to -10 V, respectively, as well as increasing the ion densities to a biased substrate from 0.2 to 5.2 mA cm-2 for each of the magnetrons. By using a ferro-powder magnetic field model, as well as finite element method analysis, we demonstrate the interference of the three magnetic fields - those of the two magnetrons and the solenoid coil. X-ray diffraction and transmission electron microscopy were used to study the microstructure and morphology of Ti-films grown under different ion bombardment conditions. At low Ar-ion-to-Ti-atom arrival rate ratios, Jion/Jn to approximately 1.5, at the substrate, variations of the ion energy, Eion, from 8 to 70 eV has only a minor effect on the microstructure and film preferred crystallographic orientation, resulting in an open/porous structure with defect-rich grains. At a higher Jion/Jn value of approximately 20, films with a well-defined dense structure were deposited at ion energies of 80 eV. The increase in ion flux also resulted in changes of the Ti film preferred orientation, from an (0 0 0 2) preferred orientation to a mixture of (0 0 0 2) and (1 0 1¯ 1) orientations.

  • 110.
    Fernandez del Rio, Lia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    An Investigation of the Polarization States of Light Reflected from Scarab Beetles of the Chrysina Genus2011Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    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.

  • 111.
    Fernandez Del Rio, Lia
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Järrendahl, Kenneth
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Polarization of light reflected from Chrysina gloriosa under various illuminations2014Inngår i: Materials Today: Proceedings, Elsevier Ltd , 2014, Vol. 1, s. 172-176Konferansepaper (Fagfellevurdert)
    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.

  • 112.
    Fernandez Del Rio, Lia
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska fakulteten.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska fakulteten.
    Järrendahl, Kenneth
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska fakulteten.
    Polarizing properties and structure of the cuticle of scarab beetles from the Chrysina genus2016Inngår i: PHYSICAL REVIEW E, ISSN 2470-0045, Vol. 94, nr 1, s. 012409-Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 113.
    Fernandez Del Rio, Lía
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Järrendahl, Kenneth
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Polarizing properties and structural characteristics of the cuticle of the scarab Beetle Chrysina gloriosa2014Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 571, nr 3, s. 410-415Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 114.
    Fernández del Río, Lia
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Landin, Jan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Magnusson, Roger
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Järrendahl, Kenneth
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    A Mueller Matrix Spectroscopic Ellipsometry Study of Scarab Beetles of the Chrysina Genus2012Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The attractive shiny metallic colour of jewel scarabs is originating from the structure of the exoskeleton.For some directions and wavelengths of the incident light this structure will also cause the reflectedlight to have a large ellipticity (near-circular polarization). This is due to that the exoskeleton is ahelicoidal structure, formed by layers of chitin molecules. The reflected light is most commonly lefthandedpolarized but right-handed polarization is also observed. In this work six species of Scarabbeetles from the Chrysina genus are investigated. The complete Mueller-matrix is measured with adual rotating compensator ellipsometer (RC2, J.A.Woollam Co., Inc.). The results are presented ascontour plots where we represent different parameters as a function of incidence angle 2[25; 75]and wavelength 2[240; 1000]nm of the incident beam. Parameters of particular interest are the m41element of the Mueller-matrix, which is related to the circular polarization behaviour, the degree ofpolarization, the ellipticity and the absolute value of the azimuth angle. From ocular observationsthrough left- and right-circularly polarizing filters all specimens showed clear polarization effects interms of colour changes. However, the Mueller matrix ellipsometry measurements showed two generaltypes of polarization behaviour depending on the studied species. Chrysina macropus and Chrysinaperuviana had a smaller range of m41 values around zero. Much larger m41 variations were observedfor Chrysina argenteola, Chrysina chrysargyrea and Chrysina resplendens. Chrysina gloriosa hadboth types of polarization behaviour depending on if the measurements where made on the green orgolden parts of this striped beetle. Comparisons among samples of beetles from the same species wereconducted. For instance, different specimens of Chrysina resplendens show rather large differences inthe polarization response whereas specimens of Chrysina chrysargyrea showed very similar polarizationbehaviour. All studied specimens did in some sense reflect both right- and left-handed polarizedlight. In many cases very high ellipticities (near-circular polarization states) were observed. Modelsof structures generating the observed polarization effects as well as biological aspects will also bediscussed.Figure 257: Three pictures of C. chrysargyrea from left to right taken with aleft-circular polarizer, no filters and with a right-circular polarizer in front of thecamera. Two contour plots of m41 for C. chrysargyrea showing a large region withleft-handed near-circular polarization and C. resplendens showing a large regionwith right-handed near-circular polarization.

  • 115.
    Filippini, Daniel
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Bakker, Jimmy
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Fingerprinting of fluorescence substances for diagnostic purposes using computer screen illumination2004Inngår i: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 106, s. 302-310Artikkel i tidsskrift (Fagfellevurdert)
  • 116.
    Filippini, Daniel
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Bakker, Jimmy
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Fingerprinting of fluorescent substances for diagnostic purposes using computer screen illumination2005Inngår i: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 106, s. 302-310Artikkel i tidsskrift (Fagfellevurdert)
  • 117.
    Gallas, B
    et al.
    University of Paris 06.
    Guth, N
    University of Paris 06.
    Rivory, J
    University of Paris 06.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Magnusson, Roger
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Guida, G
    University of Paris Ouest.
    Yang, J
    Queens University.
    Robbie, K
    Queens University.
    Nanostructured chiral silver thin films: A route to metamaterials at optical frequencies2011Inngår i: THIN SOLID FILMS, ISSN 0040-6090, Vol. 519, nr 9, s. 2650-2654Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a study of the optical properties of three-armed square nanospirals made of silver and realized as nanostructured thin films with Glancing Angle Deposition. Optical property variations with polarization were investigated using numerical simulations. For each polarisation case, two principal resonances were determined corresponding to excitation of plasmonic modes of nanospirals which resonances frequency depended on the dimensions of the nanospirals. Calculation of current flows in the nanospirals showed patterns resembling those observed in U-shaped resonators. In particular, a mode with anti-parallel current flow in opposite arms indicates the existence of a magnetic-like resonance in the square nanospirals. We present also generalized spectroscopic ellipsometry measurements obtained on one sample at an incidence angle of 25, and evidence conversion between polarization states even for light polarized in the plane containing one of the arms. The measurements showed good agreement with the results of calculations for an ideal structure. The differences in the conversion of polarization between measurements and calculations were mainly attributed to the existence of structural non-idealities in the actual sample.

  • 118.
    Gallas, B.
    et al.
    Inst de NanoSciences de Paris - CNRS, Université Pierre et Marie Curie, France.
    Rivory, J.
    Inst de NanoSciences de Paris - CNRS, Université Pierre et Marie Curie, France.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Vidal, F.
    Inst de NanoSciences de Paris - CNRS, Université Pierre et Marie Curie, France.
    Etgens, V.H.
    Inst de NanoSciences de Paris - CNRS, Université Pierre et Marie Curie, France.
    Changes in optical properties of MnAs thin films on GaAs(001) induced by a- to B-phase transition2008Inngår i: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 205, nr 4, s. 859-862Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    MnAs layers with 45 nm thickness were grown epitaxially on GaAs(001) substrates. Ellipsometry measurements were made in the spectral range 0.045 eV to 6 eV as a function of temperature (between –10 °C and 50 °C) at 70° of incidence. In this way the transition from the hexagonal α-phase to the orthorhombic β-phase could be monitored. Non-zero off-diagonal elements of the Jones matrix for an azimuth of 38° off the [10] axis of the substrate indicate that the optical functions of MnAs are anisotropic in both phases. The optical conductivity exhibits low-energy interband transitions around 0.3 eV, more clearly seen in the α-phase than in the β-phase. Extrapolation of the optical conductivity to zero frequency confirms that the α-phase is about two times more conducting than the β-phase. A broad structure is observed in the visible range around 3 eV. The α-phase is characterised by an anisotropy induced energy difference of this structure with a maximum at 2.8 eV for the extraordinary index and at 3.15 eV for the ordinary index. This difference vanishes in the β-phase in which anisotropy mainly induces changes in amplitude of the 3 eV structure. The assignment of the structures will be discussed.

  • 119.
    Gallas, B.
    et al.
    Inst des NanoSciences de Paris - CNRS, Université Pierre et Marie Curie, France.
    Rivory, J.
    Inst des NanoSciences de Paris - CNRS, Université Pierre et Marie Curie, France.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Vidal, F.
    Inst des NanoSciences de Paris - CNRS, Université Pierre et Marie Curie, France.
    Stchakovsky, M.
    Thin Film Division, Jobin-Yvon S.A.S. Horiba Group, France.
    Monitoring the a to B-phase transition in MnAs/GaAs(001) thin films as funcion of temperature2008Inngår i: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 205, nr 4, s. 863-866Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    MnAs layers with a 5 nm thick amorphous GaAs capping layer were grown epitaxially on GaAs(001). Generalized ellipsometric measurements were made on a 45 nm thick layer in the spectral range 1.5–4 eV at temperatures between –10 °C and 50 °C in steps of 5 °C. By using both the diagonal and off-diagonal elements of the Jones matrix, the in-plane unixial anisotropy of MnAs was determined in terms of the ordinary and extraordinary complex dielectric functions. The measurements at each temperature could be well reproduced by modeling using the optical properties of the two limiting phases α-MnAs and β-MnAs determined at –10 °C and 50 °C, respectively. The best sensitivity to the volume fractions of the two phases was obtained near 2.2 eV by monitoring the generalized ellipsometric parameter Δp for which the variations reached 30°.

  • 120.
    Granberg,, Hjalmar
    et al.
    Innventia AB, Stockholm, Sweden.
    Coppel,, Ludovic
    Innventia AB, Stockholm, Sweden.
    Eita, Mohamed
    KTH, Stockholm, Sweden.
    de Mayolo, Eduardo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Wågberg, Lars
    KTH, Stockholm, Sweden.
    Dynamics of moisture interaction with polyelectrolyte multilayers containing nanofibrillated cellulose2012Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, nr 2, s. 496-499Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recent findings have shown that it is possible to use the Layer-by-Layer technique to create nanofibrillated cellulose / polyethyleneimine interference films whose colour change with relative humidity. This study uses different optical models to describe spectral ellipsometry measurements data of interference films and how the film properties alter in dry and humid environments. The results indicate that water condensation initially is filling the surface pores within seconds whereas relaxation of the film to adjust to the added water is a slower process that reaches a steady state after ≈20 min. The maximum swelling ratio of the LbL films is almost independent of the number of layers within the film, but decreases considerably by crosslinking via heat treatment. The films show a distinct birefringence with optical axis perpendicular to the surface. Analysis of the moisture response with different optical models indicates that the films swell uniformly in the thickness direction with no separate water film on top. The results provide important understanding for the design of NFC based LbL films for visual moisture sensors and interactive security paper. 

  • 121.
    Gustafson, Johan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Fabrication and Characterization of Sculptured Thin Silver Films2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In this work samples with silver nanocolumnar structures were successfully fabricated by glancingangle deposition. From SEM investigations of the samples it is concluded that distinct andseparated nanocolumns can be grown without pre-patterned substrates using this method (givensuitable deposition conditions). The sample that exhibits the most distinct and well separatedcolumns was modelled using HFSS with optical properties of silver in nanocolumns obtained bymeasurements on the samples grown by glancing angle deposition, thin enough to not havedeveloped columns. From numerical calculations it was shown that the unit cell arrangement of thecolumns has a large influence on the optical characteristics. It was found that a diamond-like unitcell designed as two identical square lattices shifted by half the lattice spacing in one direction and2-1/2 times the lattice spacing of the other direction gives the best and a fair agreement to theexperimental ellipsometry data. Based on this model calculations were made to determine thewavelength dependent average local current exhibited in the columns as well as the currentdensity. This study showed the occurrence of broadbanded plasmon resonances of longitudinalmode at λ=1363 nm and of transverse mode at λ=545 nm. It was also shown that the opticalcharacteristics are strongly polarization dependent as is expected for such anisotropic samples.

  • 122.
    Gustafson, Johan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Optical Studies and Micro-Structure Modeling of the Circular-Polarizing Scarab Beetles Cetonia aurata, Potosia cuprea, Liocola marmorata2010Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    The aim of the work presented in this thesis is to contribute to a fundamental understanding of polarizing phenomena in some scarab beetles. The aim is also to study the beetle structures as inspiration in fabrication of artificially sculptured films. The three investigated species Cetonia aurata, Potosia cuprea and Liocola marmorata are of the family Scarabaediae and subfamily Cetoniianae (Guldbaggar). They were all collected at Swedish locations and are the only species of Cetoniinae scarabs in Sweden. This work reports on their optical properties represented by Mueller matrix elements, degree of polarization data and trace curves in the Cartesian complex plane representation of polarized light. From these results we verifyan earlier structural model for the Cetonia aurata and make way for similar models of the other two species.

    The ellipsometer used in this work is of dual rotating compensator type from which the complete Mueller-matrix for the medium examined can be obtained. The ellipsometric measurements were conducted on the scutellum for four different angles of incidence, 45°, 55°, 65° and 75° over a wave-length range of 245-1000 nm.

    Common for all examined species is that left polarization is observed in the wavelength range of 400 800 nm. For most of these species the polarization state is close to circular at some wavelengths especially at smaller angles of incidence. In general the degree of polarization is high (above 50%) when the polarization is near-circular. The degree of polarization also shows a clear dependence on the angle of incidence. The earlier model for Cetonia aurata shows a good agreement with the experimental data of this work. The model is also found as a good basis to work from to create models for the other two species.

  • 123. Gustafsson, C
    et al.
    Chen, Jiaxin
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Forsgren, B
    Corrosion Kinetics of Nickel-base Alloys in Simulated BWR Conditions under High Flow Velocity2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Corrosion-induced material degradation of nickel-base alloys is a critical issue of material integrity and plant operation safety. It is therefore important to determine alloy corrosion rates and to examine corrosion resistant properties of the oxide films formed on the alloy surfaces. This paper contributes to a corrosion kinetic study on nickel-base alloys 82, 182 and 600 in a specially constructed loop system capable of simulating BWR water environments under high flow velocity. The corrosion rate data are derived from measurements of weight changes of test coupons, oxide thicknesses with infrared ellipsometry, and microstructures of oxide films with high resolution electron microscopy. For the alloys examined, corrosion rates decreased with time, suggesting that the formed oxide films were likely protective. Although the overall thicknesses of the oxide films on Alloy 82 and 600 were vastly different from each other, they corroded equally much after nine weeks exposure. Comparing the corrosion rates for Alloys 182 and 600, on the other hand, one finds that the very thick oxide films formed on Alloy 600 did not make the alloy corrode more slowly but more rapidly. These observations indicate that the overall thickness of oxide scales, being largely porous, did not contribute to alloy corrosion protection. The possible rate-limiting step occurring in the inner-most thin but tenacious oxide films at the metal/oxide interface regions is briefly discussed.

  • 124.
    Hellgren, Niklas
    et al.
    Intel Corporation, Portland Technology Development, RA3-301, 5200 NE Elam Young Parkway, Hillsboro, OR 97124, USA.
    Berlind, Torun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Gueorguiev, Gueorgui K.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Johansson, Mats P.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Stafström, Sven
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Fullerene-like B C N thin films a computational andexperimental study2004Inngår i: Materials Science and Engineering B, Vol. 113, nr 3, s. 242-247Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ab initio calculations show that the energy cost for incorporating lattice defects such as pentagons and heptagons is significantly reduced for BCN compared to BN, thus promoting bending of basal planes in these compounds. Boron–carbon–nitride (Bsingle bondCsingle bondN) thin films with a fullerene-like (FL) microstructure were then deposited by dual cathode magnetron sputtering from C and B4C targets. Up to 1 μm thick films were grown at a total gas pressure of 3 mTorr (0.4 Pa) in varying Ar/N2 ratios, and substrate temperatures between 225 and 350 °C. Compositional and microstructural studies were performed using RBS, SEM and HREM, respectively. Depending on the deposition condition, ternary BxCyNz films with fullerene-like microstructure could be prepared in agreement with the calculations within the composition range 0 ≤ x ≤ 53, 15 ≤ y ≤ 62, and 24 ≤ z ≤ 50 at.%. Fullerene-like structures also tend to form at lower temperatures in the case of BCN compared to CN. Nanoindentation measurements show that all BxCyNz films exhibited a highly elastic response independent of elemental composition. In addition, the calculations suggest a driving force for C and BN phase separation.

  • 125.
    Hollertz, Rebecca
    et al.
    KTH Royal Institute Technology, Sweden.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Faure, Bertrand
    Stockholm University, Sweden.
    Zhang, Yujia
    KTH Royal Institute Technology, Sweden.
    Bergstrom, Lennart
    Stockholm University, Sweden.
    Wagberg, Lars
    KTH Royal Institute Technology, Sweden.
    Dielectric properties of lignin and glucomannan as determined by spectroscopic ellipsometry and Lifshitz estimates of non-retarded Hamaker constants2013Inngår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 20, nr 4, s. 1639-1648Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present in this study a quantitative estimate of the dispersive interactions between lignin, hemicellulose and cellulose, which are the dominating components in wood and also extensively used to produce paper and packaging materials. The dielectric properties in the UV-visible region of spin-coated films of pure lignin and glucomannan were determined by spectroscopic ellipsometry. The non-retarded Hamaker constants were estimated from the determined spectral parameters using Lifshitz theory for lignin and glucomannan interacting with cellulose, titania and calcium carbonate in vacuum, water and hexane. The Hamaker constants for the different combinations of cellulose, lignin and glucomannan fall within a relatively narrow range of 35–58 and 8–17 zJ, for the values in vacuum (air) and water, respectively. The estimated Hamaker constants for the interactions of the wood components with TiO2 and CaCO3, common additives in paper, in water range from 3 to 19 zJ, thus being similar in magnitude as the interactions between the wood components themselves. In contrast, the Hamaker constant is essentially zero for glucomannan interacting with calcium carbonate in hexane. The Hamaker constants for lignin, hemicellulose and cellulose determined in this study can provide information regarding the surface interactions important for e.g. adhesion, friction, swelling and wetting in paper processing as well as for the resulting behavior of paper products.

  • 126.
    Hsiao, Ching-Lien
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Magnusson, Roger
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Sandström, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Persson, Per O. Å.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Valyukh, Sergiy
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Järrendahl, Kenneth
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Curved-Lattice Epitaxial Growth of InxAl1-xN Nanospirals with Tailored Chirality2015Inngår i: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 15, nr 1, s. 294-300Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Chirality, tailored by external morphology and internal composition, has been realized by controlled curved-lattice epitaxial growth (CLEG) of uniform coatings of single-crystalline InxAl1-xN nanospirals. The nanospirals are formed by sequentially stacking segments of curved nanorods on top of each other, where each segment is incrementally rotated around the spiral axis. By controlling the growth rate, segment length, rotation direction, and incremental rotation angle, spirals are tailored to predetermined handedness, pitch, and height.  The curved morphology of the segments is a result of a lateral compositional gradient across the segments while maintaining a preferred crystallographic growth direction, implying a lateral gradient in optical properties as well. Left- and right-handed nanospirals, tailored with 5 periods of 200 nm pitch, as confirmed by scanning electron microscopy, exhibit uniform spiral diameters of ~80 nm (local segment diameters of ~60 nm) with tapered hexagonal tips.  High resolution electron microscopy, in combination with nanoprobe energy dispersive X-ray spectroscopy and valence electron energy loss spectroscopy, show that individual nanospirals consist of an In-rich core with ~15 nm-diameter hexagonal cross-section, comprised of curved basal planes. The core is surrounded by an Al-rich shell with a thickness asymmetry spiraling along the core. The ensemble nanospirals, across the 1 cm2 wafers, show high in-plane ordering with respect to shape, crystalline orientation, and direction of compositional gradient. Mueller matrix spectroscopic ellipsometry shows that the tailored chirality is manifested in the polarization state of light reflected off the CLEG nanospiral-coated wafers. In that, the polarization state is shown to be dependent on the handedness of the nanospirals and the wavelength of the incident light in the ultraviolet-visible region.

  • 127.
    Hsiao, Ching-Lien
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Magnusson, Roger
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Sandström, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Valyukh, Sergiy
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Persson, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Järrendahl, Kenneth
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Curved-lattice epitaxial growth of chiral AlInN twisted nanorods for optical applications2012Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Despite of using chiral metamaterials to manipulate light polarization states has been demonstrated their great potential for applications such as invisible cloaks, broadband or wavelength-tunable circular polarizers, microreflectors, etc. in the past decade [1-6], operating wavelength in ultraviolet-visible range is still a challenge issue. Since these chiral structures often consist of metallic materials, their operation is designed for the infrared and microwave regions [2-4]. Here, we show how a controlled curved-lattice epitaxial growth (CLEG) of wide-bandgap AlInN semiconductor curved nanocrystals [7] can be exploited as a novel route for tailoring chiral nanostructures in the form of twisted nanorods (TNRs). The fabricated TNRs are shown to reflect light with a high degree of polarization as well as a high degree of circular polarization (that is, nearly circularly polarized light) in the ultravioletvisible region. The obtained polarization is shown to be dependent on the handedness of the TNRs.

  • 128. Isidorsson, J
    et al.
    Giebels, IAME
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Griessen, R
    Optical properties of MgH2 measured in situ by ellipsometry and spectrophotometry2003Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 68, nr 11Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The dielectric properties of alpha-MgH2 are investigated in the photon energy range between 1 and 6.5 eV. For this purpose, a sample configuration and experimental setup are developed that allow both optical transmission and ellipsometric measurements of a transparent thin film in equilibrium with hydrogen. We show that alpha-MgH2 is a transparent, color neutral insulator with a band gap of 5.6+/-0.1 eV. It has an intrinsic transparency of about 80% over the whole visible spectrum. The dielectric function found in this work confirms very recent band-structure calculations using the GW approximation by Alford and Chou (unpublished). As Pd is used as a cap layer we report also the optical properties of PdHx thin films.

  • 129.
    Jansson, Roger
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Zangooie, S
    Linkoping Univ, Dept Phys & Measurement Technol, Appl Phys Lab, SE-58183 Linkoping, Sweden.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Järrendahl, Kenneth
    Linköpings universitet, Tekniska högskolan.
    Characterization of 3C-SiC by spectroscopic ellipsometry2000Inngår i: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 218, nr 1, s. R1-R2Artikkel i tidsskrift (Fagfellevurdert)
  • 130.
    Jansson, Roger
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Zangooie, S.
    Center for Microelectronic and Optical Materials Research, Department of Electrical Engineering, University of Nebraska, Lincoln, NE 68588-0511, United States.
    Kugler, T.
    Acreo AB, Interconncet and Packaging, Bredgatan 34, SE-602 21 Norrköping, Sweden.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Optical and microstructural characterization of thin films of photochromic fulgides2001Inngår i: Journal of Physics and Chemistry of Solids, ISSN 0022-3697, E-ISSN 1879-2553, Vol. 62, nr 7, s. 1219-1228Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Variable angle spectroscopic ellipsometry has been used for determining the optical properties, in terms of the complex dielectric function in the near UV-VIS-near IR spectral range, and the thicknesses of thin fulgide films of type E-a-(2,5-dimethyl-3-furyl)-ethylidene(adamantylidene)succinic anhydride and (E)-2-[a-(2,5-dimethyl-3-thienyl)ethylidene]-3-isopropylidenesuccinic anhydride. The films had thicknesses in the range 28-40 nm and were spin coated onto silicon substrates. To simultaneously extract film thicknesses and optical properties of the films, several methods of analysis were employed in order to decrease correlation between the fitting parameters in the optical model of the structure. In agreement with previous absorbance measurements done by others on similar materials in liquid or solid form, it was found that the fulgides studied have several resonances in the wavelength region below 400 nm and that new resonances appear in the middle of the visible region upon UV exposure. The ellipsometric analysis, as well as atomic force microscopy studies, showed that the films were very smooth with a root mean square surface roughness <0.4 nm and that a small thickness change of the film takes place upon UV exposure. Furthermore, AFM studies revealed that large phase changes take place when the samples are stored in darkness for several days, indicating that the materials are not stable in thin film form. © 2001 Elsevier Science Ltd.

  • 131. Johansen, K
    et al.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Liedberg, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Sensorvetenskap och Molekylfysik.
    Imaging surface plasmon resonance sensor based on multiple wavelengths: Sensitivity considerations2000Inngår i: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 71, nr 9, s. 3530-3538Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new, multiple wavelength surface plasmon resonance apparatus for imaging applications is presented. It can be used for biosensing, e.g., for monitoring of chemical and biological reactions in real time with label-free molecules. A setup with a fixed incident angle in the Kretschmann configuration with gold as the supporting metal is described, both theoretically and experimentally. Simulations of the sensor response based on independently recorded optical (ellipsometric) data of gold show that the sensitivity for three-dimensional recognition layers (bulk) increases with increasing wavelength. For two-dimensional recognition layers (adlayer) maximum sensitivity is obtained within a limited wavelength range. In this situation, the rejection of bulk disturbances, e.g., emanating from temperature variations, decreases, with increasing wavelength. For imaging surface plasmon resonance the spatial resolution decreases with increasing wavelength. Hence, there is always a compromise between spatial resolution, bulk disturbance rejection, and sensitivity. Most importantly, by simultaneously using multiple wavelengths, it is possible to maintain a high sensitivity and accuracy over a large dynamic range. Furthermore, our simulations show that the sensitivity is independent of the refractive index of the prism. (C) 2000 American Institute of Physics. [S0034-6748(00)02909-9].

  • 132. Johansson, M P
    et al.
    Hellgren, N.
    Berlind, Torun
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Broitman, E.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Sundgren, J.-E.
    Growth of CNx/BN: C multilayer films by magnetron sputtering2000Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 360, nr 1-2, s. 17-23Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Symmetric CNx/BN:C multilayer thin films, with nominal compositional modulation periods of ? = 2.5, 5, and 9 nm were deposited by unbalanced dual cathode magnetron sputtering from C (graphite) and B4C targets in an Ar/N2 (60/40) discharge. The multilayers and single-layer of the constituent CNx and BN:C compounds were grown to a total thickness of 0.5 µm onto Si(001) substrates held at 225°C and a negative floating potential of approx. 30 V (Ei = 24 eV). Layer characterizations were performed by TEM, X-ray reflectivity, RBS, and nanoindentation measurements. Results show that CN0.33 and BN:C (35, 50, and 15 at.% of B, N, and C, respectively) layers were prepared at the above conditions. It is suggested that all films exhibit a three-dimensional interlocked structure with a cylindrical texture in the film growth direction. The structure was continuous over relatively well defined and smooth CNx/BN:C interfaces. All coatings exhibit extreme elasticity with elastic recoveries as high as 85-90% (10 mN maximum load) attributed to the observed structure. However, the multilayers were stiffer and more elastic compared to that of the single-layers and thus shows promise for improved protective properties.

  • 133.
    Johansson, Malin B.
    et al.
    Uppsala University, Sweden .
    Baldissera, Gustavo
    Royal Institute of Technology KTH, Stockholm, Sweden .
    Valyukh, Iryna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Persson, Clas
    Royal Institute of Technology KTH, Stockholm, Sweden .
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Niklasson, Gunnar A.
    Uppsala University, Sweden .
    Osterlund, Lars
    Uppsala University, Sweden .
    Electronic and optical properties of nanocrystalline WO3 thin films studied by optical spectroscopy and density functional calculations2013Inngår i: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 25, nr 20, s. 205502-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The optical and electronic properties of nanocrystalline WO3 thin films prepared by reactive dc magnetron sputtering at different total pressures (P-tot) were studied by optical spectroscopy and density functional theory (DFT) calculations. Monoclinic films prepared at low P-tot show absorption in the near infrared due to polarons, which is attributed to a strained film structure. Analysis of the optical data yields band-gap energies E-g approximate to 3.1 eV, which increase with increasing P-tot by 0.1 eV, and correlate with the structural modifications of the films. The electronic structures of triclinic delta-WO3, and monoclinic gamma- and epsilon-WO3 were calculated using the Green function with screened Coulomb interaction (GW approach), and the local density approximation. The delta-WO3 and gamma-WO3 phases are found to have very similar electronic properties, with weak dispersion of the valence and conduction bands, consistent with a direct band-gap. Analysis of the joint density of states shows that the optical absorption around the band edge is composed of contributions from forbidden transitions (andgt;3 eV) and allowed transitions (andgt;3.8 eV). The calculations show that E-g in epsilon-WO3 is higher than in the delta-WO3 and gamma-WO3 phases, which provides an explanation for the P-tot dependence of the optical data.

  • 134.
    Johs, Blaine
    et al.
    JA Woollam Co Inc, USA.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Wagner, Thomas
    LOT Oriel GmbH and Co KG, Germany.
    Appel, David
    LOT Oriel GmbH and Co KG, Germany.
    Peros, Dimitrios
    ALANOD Aluminium-Veredlung GmbH & Co. KG, Germany.
    Accuracy of color determination from spectroscopic ellipsometry measurements2011Inngår i: THIN SOLID FILMS, ISSN 0040-6090, Vol. 519, nr 9, s. 2711-2714Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In many coating and display applications, quantitative determination of the sample color is required. Standard procedures exist for converting an experimentally measured reflectivity spectrum into color coordinates such as CIE L*a*b*. In this paper we evaluate CIE L*a*b* color coordinates using a reflectivity spectrum which is calculated from an optical model determined by a spectroscopic ellipsometry (SE) analysis of the sample. The accuracy of the SE-determined color coordinates are compared with traditional color measurements, and the advantages of using SE for color determination are discussed.

  • 135.
    Järrendahl, Kenneth
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Polarizing Natural Nanostructures2014Inngår i: Ellipsometry of Functional Organic Surfaces and Films / [ed] Hinrichs, Karsten; Eichhorn Klaus-Jochen, Springer Berlin/Heidelberg, 2014, s. 155-169Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    A brief description of the polarizing environment we are living in and the possibilities for some animals to detect this polarization is made. This is followed by a presentation of how animals and plants generate polarized light, usually through reflection from micro- and nanostructures. Special attention is made to scarab beetles reflecting light with a high degree of circular polarization. Finally some comments on the biological aspects of polarization are made.

  • 136.
    Järrendahl, Kenneth
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Magnusson, Roger
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Hsiao, Ching-Lien
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Sandström, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Berlind, Torun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Gustafson, Johan L.I.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Fernández del Río, Lia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Landin, Jan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Polarization of Light Reflected from Chiral Structures - Calculations Compared with Mueller Matrix Ellipsometry Measurements on Natural and Synthetic Samples2012Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The Mueller matrix elements mij representing the polarization response from a nanostructured materialis determined by the constituent materials optical properties and the superstructure. Here, we investigate how chiral structures in form of helicoidally stacked uniaxial layers determine mij as a functionof polarization state, wavelength, incidence angle and azimuthal angle of the incoming light. The studied parameters include the layer materials ordinary/extraordinary optical properties, Euler angle values, and layer thickness as well as the thickness and pitch of the helicoidal superstructure. Sub- and superstructure inhomogeneity is also introduced. From the Fresnel-based calculations, mij aswell as the degree of polarization, ellipticity and azimuth of the polarization ellipse are obtained and presented as contour and trace plots to give a complete view of the polarization behavior. The results from the calculations are compared with Mueller matrix spectroscopic ellipsometry measurements of both natural and synthesized helicoidal structures. The measurements were performed with a dualrotating compensator system (RC2, J.A. Woollam Co., Inc.) for wavelengths in the range from 245 to 1000 nm and incident angles from 20 to 75°. For some measurements the azimuthal angle of the incident light was varied. The investigated natural chiral structures were exoskeletons from several beetles in the scarab subfamilies Cetoniinae and Rutelinae. As predicted from the calculations it isobserved that the reflection from these beetles can have a high degree of polarization and high ellipticity (near-circular polarization). Both left- and right-polarization was observed. The synthesized structures are helicoidal nanorods of Al1−xInxN grown on sapphire substrates with metal-nitride seedlayers using UHV magnetron sputtering. Due to an internal composition gradient (a variation of x) in the crystalline structure, the nanorods will tilt away from the substrate normal. Helicoidal structures can thus be obtained by rotating the substrate around its normal during deposition. Samples with different pitch and layer thickness with right-handed as well as left-handed chirality were grown. Also for these structures both left and right near-circular polarized light is observed. By combining calculations, ellipsometry measurements and scanning electron microscopy characterization we get agood input to build layered models of the natural and synthetic samples. After regression fitting agood agreement between calculated and measured optical data were obtained.

  • 137.
    Järrendahl, Kenneth
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Landin, Jan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ekologi. Linköpings universitet, Tekniska högskolan.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Mueller-Matrix Ellipsometry Studies of Optically Active Structures in Scarab2009Konferansepaper (Annet vitenskapelig)
  • 138.
    Järrendahl, Kenneth
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Landin, Jan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ekologi. Linköpings universitet, Tekniska högskolan.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Mueller-Matrix Ellipsometry Studies of Optically Active Structures in Scarab Beerles (conf. France)2009Konferansepaper (Annet vitenskapelig)
  • 139.
    Järrendahl, Kenneth
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Landin, Jan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ekologi. Linköpings universitet, Tekniska högskolan.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Mueller-Matrix Ellipsometry Studies of Optically Active Structures in Scarab Beetles2009Konferansepaper (Annet vitenskapelig)
  • 140.
    Karlsson, L M
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Tengvall, Pentti
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Adsorption of human serum albumin in porous silicon gradients2003Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Backside etching has been utilized to produce gradients of pore size and layer thickness in porous silicon. Human serum albumin (HSA) was adsorbed on such gradients at two different pH values: 4.9, the pI of HSA, and 7.4, the physiological pH. The samples were investigated by scanning electron microscopy, spectroscopic ellipsometry, and autoradiography. The results show that the protein adsorbed displays a gradient along with the pore size and the thickness gradient. The higher than current density used during etching, the more sway-back shaped curves were seen for the protein adsorption pattern, independent of pH. When 50 mA/cm2 current density was used during etching, the quota between the maximal intensity value and the plateau value seen after adsorption of the HSA increased for pH 7.4.

  • 141.
    Karlsson, L M
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Tengvall, Pentti
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Back-side etching A tool for making morphology gradients in porous silicon2002Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 149, nr 12Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new method for preparing morphology gradients in electrochemically etched porous silicon layers in presented. The idea is to etch on the back side of the anode and thus utilize and inhomogenous electric field to control the pore size along a surface. The etching procedure resulted in a complex gradient in pore size, porosity, and porous layer thickness, which was studied by spectroscopic ellipsometry and scanning electron microscopy. The gradients are of interest, e.g., for biomaterials research, bio-sensor applications, and for basic studies of adsorption of organic molecules, like proteins. In order to investigate the potential of the gradient surfaces for protein adsorption studies, these were exposed to human serum albumin, and a gradient in the amount of adsorbed protein was observed.

  • 142.
    Karlsson, L M
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Tengvall, Pentti
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Penetration and loading of human serum albumin in porous silicon layers with different pore sizes and thicknesses2003Inngår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 266, nr 1, s. 40-47Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Human serum albumin was adsorbed into porous silicon layers with thickness up to 3 µm and with different mean pore radius in the range 4.5-10 nm. The adsorbed amount of protein was quantified by I125 radioactive labeling techniques and ellipsometry. The results show that albumin penetrated into the pores when the mean pore radius was larger than 5.5 nm, but could not totally occupy the available surface area when the layer thickness was larger than 1 µm. Loading of albumin both into porous layers and onto plane silicon as a function of albumin concentration was also investigated. These measurements show that loading of protein increased with protein concentration at least up to 10 mg/ml for porous silicon and up to 1 mg/ml for plane silicon. The maximum deposition into the type of porous layers used here was 28 µg/cm2, compared to 0.36 µg/cm2 for plane silicon. © 2003 Elsevier Inc. All rights reserved.

  • 143.
    Karlsson, Linda
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Schubert, Mattias
    Institute for Experimental Physics II University of Leipzig, Germany.
    Ashkenov, N.
    Institute for Experimental Physics II University of Leipzig, Germany.
    Adsorption of human serum albumin in porous silicon gradients monitored by spatially-resolved spectroscopic ellipsometry2005Inngår i: Physica status solidi, ISSN 0031-8957, Vol. 2, s. 3293-3297Artikkel i tidsskrift (Fagfellevurdert)
  • 144.
    Karlsson, Linda
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Scubert, Mattias
    Inst for Experimental Physics II University of Leipzig.
    Ashkenov, N.
    Inst for Experimental Physics II University of Leipzig.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Protein adsorption in porous silicon gradients monitored by spatially-resolved spectroscopic ellipsometry2004Inngår i: Elsevier Science, ISSN 1626-3200, Vol. 455-456, s. 726-730Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Porous silicon layers with a one-dimensional lateral gradient in pore size are prepared by electrochemical etching and characterized by spectroscopic ellipsometry in the visible to near-infrared region. The ellipsometer is equipped with a micro-spot option giving a lateral resolution of approximately 100 μm. By matching multiple-layer-model calculations to the laterally-resolved variable angle of incidence spectroscopic ellipsometry data, the thickness variation along the gradient as well as the in-depth porosity profile is mapped. Upon exposure to a protein solution, protein adsorption occurs on top of the porous silicon layer. At the high-porosity region of the gradient also penetration of protein molecules into the porous layer takes place. Ellipsometry data are recorded after protein exposure and variations of protein adsorption along the porous silicon gradient is modeled as well as the in-depth profile of protein penetration.

  • 145. Karpus, V.
    et al.
    Babonas, G-J.
    Reza, A.
    Tumenas, S.
    Arwin, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik.
    Wassmus, NN
    Brühne, S.
    Optical responce of si-ZnMgHo quasicrystal2008Inngår i: 10th International Conference on Quasicrystals,2008, Zürich: ETH , 2008Konferansepaper (Fagfellevurdert)
  • 146.
    Karpus, V.
    et al.
    Centre Phys Science and Technology, Lithuania.
    Tumenas, S.
    Centre Phys Science and Technology, Lithuania.
    Eikevicius, A.
    Centre Phys Science and Technology, Lithuania.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska fakulteten.
    Interband optical transitions of Zn2016Inngår i: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 253, nr 3, s. 419-428Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Experimental results of an optical study of single-crystal zinc are presented. Components of the Zn dielectric function tensor were measured by spectroscopic ellipsometry in the 0.1-5 eV spectral range. In the NIR-VIS range, the dielectric function spectra show two clearly resolved, polarization-dependent optical features located at about 1 and 1.7 eV. The optical features were analyzed in a framework of parallel-band optical transitions. The performed theoretical calculations of the optical conductivity spectra well reproduce the experimental data with respect to positions, intensities, and polarization dependencies of the observed interband absorption peaks. (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  • 147.
    Karpus, V
    et al.
    Institute Semicond Phys, Lithuania.
    Tumenas, S
    Institute Semicond Phys, Lithuania.
    Suchodolskis, A
    Institute Semicond Phys, Lithuania.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Assmus, W
    Goethe University of Frankfurt, Germany.
    Optical spectroscopy and electronic structure of the face-centered icosahedral quasicrystals Zn-Mg-R (R=Y, Ho, Er)2013Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 88, nr 9Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Results of optical spectroscopy studies of the face-centered icosahedral (fci) single-grain Zn-Mg-Y, Zn-Mg-Ho, and Zn-Mg-Er quasicrystals (QCs) are presented. The dielectric function of the QCs was measured in the 0.01–6 eV spectral range by IR-UV spectroscopic ellipsometry and far infrared reflection spectroscopy techniques. A theoretical scheme of optical conductivity calculations is extended to account for the Fermi level positions within and below a pseudogap. The model of the QC electron energy spectrum, based on a band structure hypothesis, is suggested, which treats the electronic subsystem as a nearly free electron gas affected by intersections of the Fermi surface with several families of Bragg planes. The experimental optical spectra are reproduced in detail by theoretical calculations carried out within the framework of the model. The parameters of the electron energy spectrum deduced from an analysis of optical data are close to those previously determined in an analysis of fci Zn-Mg-R valence band photoemission spectra.

  • 148.
    Karpus, Vytautas
    et al.
    Institute for Semiconductor Physics, Lithuania.
    Babonas, Gintautas-Jurgis
    Institute for Semiconductor Physics, Lithuania.
    Reza, Alfonsas
    Institute for Semiconductor Physics, Lithuania.
    Tumenas, Saulius
    Institute for Semiconductor Physics, Lithuania.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Assmus, Wolf
    University of Frankfurt.
    Bruehne , Stefan
    University of Frankfurt.
    Optical response of si-ZnMgHo quasicrystal2009Inngår i: ZEITSCHRIFT FUR KRISTALLOGRAPHIE, ISSN 0044-2968 , Vol. 224, nr 1-2, s. 39-41Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The results of room-temperature optical study of single-grain simple icosahedral ZnMgHo quasicrystals are presented. The dielectric function epsilon(omega) of the quasicrystals was measured by spectroscopic ellipsometry technique in the spectral range of 0.1 - 7 eV. The si-ZnMgHo optical response is a superposition of the free-electron Drude-type contribution and that of the interband transitions. The experimental epsilon(omega) spectra are well simulated within a framework of the band structure hypothesis. The deduced parameters of the si-ZnMgHo electron energy spectrum are close to their values determined previously in an analysis of the si-ZnMgHo photoemission data.

  • 149.
    Lansåker, Pia
    et al.
    Uppsala University, Uppsala, Sweden.
    Tuncer, Enis
    3M Austin Center, Austin, USA.
    Valyukh, Iryna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Arwin, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska högskolan.
    Niklasson, Gunnar
    Uppsala University, Uppsala, Sweden.
    Granqvist, Claes Göran
    Uppsala University, Uppsala, Sweden.
    Spectral  density analysis of thin gold films: Thickness and structure dependence of the optical properties2013Inngår i: Proceedings, ISSN 0351-6067, s. 443-447Artikkel, omtale (Annet vitenskapelig)
    Abstract [en]

    In this paper we study the feasibility of representing the optical properties of ultrathin gold films by effective medium theories. Gold films with mass thicknesses in the range of 1.4 to 9.2 nm were deposited by DC magnetron sputtering onto non-heated glass substrates. Optical measurements in the range 0.25 to 2 µm were carried out by spectroscopic ellipsometry, and the effective complex dielectric function of each film was determined. The gold films were modelled as a mixture of gold and air, and a general effective medium description using the spectral density function (SDF) was used to describe their optical properties. Numerical inversion of the experimental dielectric function gave a broad and rather featureless SDF with a few superimposed peak structures, both for island structures and percolating films. The broad background is qualitatively similar to the predictions of the Bruggeman [Ann. Phys. (Leipzig), 5th series, 24 (1935) 636-679] model.

  • 150.
    Lettieri, Raffaella
    et al.
    University of Roma Tor Vergata, Italy.
    Di Giorgio, Floriana
    University of Roma Tor Vergata, Italy.
    Colella, Alessandra
    University of Roma Tor Vergata, Italy.
    Magnusson, Roger
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad optik. Linköpings universitet, Tekniska fakulteten.
    Björefors, Fredrik
    Uppsala University, Sweden.
    Placidi, Ernesto
    University of Roma Tor Vergata, Italy.
    Palleschi, Antonio
    University of Roma Tor Vergata, Italy.
    Venanzi, Mariano
    University of Roma Tor Vergata, Italy.
    Gatto, Emanuela
    University of Roma Tor Vergata, Italy.
    DPPTE Thiolipid Self-Assembled Monolayer: A Critical Assay2016Inngår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 32, nr 44, s. 11560-11572Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Supported lipid membranes represent an elegant way to design a fluid interface able to mimic the physicochemical properties of biological membranes, with potential biotechnological applications. In this work, a diacyl phospholipid, the 1,2-dipalmitoyl-sn-glycero-3-phosphothioethanol (DPPTE), functionalized with a thiol group, was immobilized on a gold surface. In this molecule, the thiol group, responsible for the Au S bond (45 kJ/mol) is located on the phospholipid polar head, letting the hydrophobic chain protrude from the film. This system is widely used in the literature but is no less challenging, since its characterization is not complete, as several discordant data have been obtained. In this work, the film was characterized by cyclic voltammetry blocking experiments, to verify the SAM formation, and by reductive desorption measurements, to estimate the molecular density of DPPTE on the gold surface. This value has been compared to that obtained by quartz crystal microbalance measurements. Ellipsometry and impedance spectroscopy measurements have been performed to obtain information about the monolayer thickness and capacitance. The film morphology was investigated by atomic force microscopy. Finally, Monte Carlo simulations were carried out, in order to gain molecular information about the morphologies of the DPPTE SAM and compare them to the experimental results. We demonstrate that DPPTE molecules, incubated 18 h below the phase transition temperature (T = 41.1 +/- 0.4 degrees C) in ethanol solution, are able to form a self-assembled monolayer on the gold surface, with domain structures of different order, which have never been reported before. Our results make possible rationalization of the scattered results so far obtained on this system, giving a new insight into the formation of phospholipids SAMs on a gold surface.

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