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  • 1.
    Butorin, S. M.
    et al.
    Uppsala University.
    Guo, J.-H.
    Uppsala University.
    Magnuson, Martin
    Uppsala University.
    Kuiper, P.
    Uppsala University.
    Nordgren, J.
    Uppsala University.
    Low-energy d-d excitations in MnO studied by resonant x-ray fluorescence spectroscopy1996In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, Vol. 54, 4405-4408 p.Article in journal (Refereed)
    Abstract [en]

    We measured the Mn Lα,β x-ray fluorescence spectra of MnO excited by selected photon energies near the L2,3 absorption edges. The resulting resonant inelastic x-ray scattering spectra probe low-lying electronic excited states, due to dd and charge-transfer excitations. Using a two-step model and a purely atomic approximation, we reproduce both energies and varying intensities of dd excitations relative to the electronic recombination peak. Our results show that strongly varying line shapes in resonant x-ray emission need not be due to channel interference effects.

  • 2.
    Butorin, S. M.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Guo, J.-H.
    Uppsala University.
    Magnuson, Martin
    Uppsala University.
    Nordgren, J.
    Uppsala University.
    Resonant inelastic soft-x-ray scattering from valence-band excitations in 3d0 compounds1997In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, Vol. 55, 4242-4249 p.Article in journal (Refereed)
    Abstract [en]

    Ti and Mn Lα,Β x-ray fluorescence spectra of FeTiO3 and KMnO4 were measured with monochromatic photon excitation on selected energies across the L2,3 absorption edges. The resulting inelastic x-ray-scattering structures and their changes with varying excitation energies are interpreted within the framework of a localized, many-body approach based on the Anderson impurity model, where the radiative process is characterized by transitions to low-energy interionic-charge-transfer excited states. Sweeping the excitation energy through the metal 2p threshold enhances the fluorescence transitions to the antibonding states pushed out of the band of continuous states due to strong metal 3d–ligand 2p hybridization and matching the low-photon-energy satellites in the spectra. Based on the energy position of these charge-transfer satellites with respect to the recombination peak the effective metal 3d–ligand 2p hybridization strength in the ground state of the system can be estimated directly from the experiment.

  • 3.
    Butorin, S. M.
    et al.
    Physics Departmen, Uppsala University, Uppsala, Sweden.
    Guo, J.
    Physics Departmen, Uppsala University, Uppsala, Sweden.
    Magnuson, Martin
    Physics Departmen, Uppsala University, Uppsala, Sweden.
    Kuiper, P.
    Physics Departmen, Uppsala University, Uppsala, Sweden.
    Nordgren, J.
    Physics Departmen, Uppsala University, Uppsala, Sweden.
    Low-Energy d-d Excitations in MnO Studied by Resonant X-ray Fluorescence Spectroscopy1997In: Advanced Light Source: Compendium of User Abstracts and Technical Reports 1993-1996 / [ed] Deborah J. Dixon, jane Cross, Kathryn Devereaux, and Annette Greiner, Berkely: Ernest Orlando Lawrence Berkeley National Laboratory University of California Berkeley, California , 1997, 135-136 p.Chapter in book (Other academic)
    Abstract [en]

    Resonant soft X-ray emission spectroscopy has been demonstrated to possess interesting abilities for studies of electronic structure in various systems, such as symmetry probing, alignment and polarization dependence, sensitivity to channel interference, etc. (see other abstracts in this Annual Report). In the present abstract we focus on the feasibility of resonant soft X-ray emission to probe low energy excitations by means ofresonant electronic X-ray Raman scattenng....

  • 4.
    Butorin, S. M.
    et al.
    Uppsala University.
    Guo, J.-H.
    Uppsala University.
    Magnuson, Martin
    Uppsala University.
    Kuiper, P.
    Nordgren, J.
    Uppsala University.
    ALS compendium of user abstracts and technical reports 1993-1996, April (1997)1997Report (Other academic)
  • 5.
    Butorin, S. M.
    et al.
    Uppsala University.
    Magnuson, Martin
    Uppsala University.
    Ivanov, K.
    Lawrence Berkeley National Laboratory, Berkeley, USA.
    Shuh, D. K.
    Lawrence Berkeley National Laboratory, Berkeley, USA.
    Takahashi, T.
    Tohoku University, Japan.
    Kunii, S.
    Tohoku University, Japan.
    Guo, J.-H.
    Uppsala University.
    Nordgren, J.
    Uppsala University.
    Resonant inelastic soft X-ray scattering at the 4d edge of Ce-based heavy fermion materials1999In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, Vol. 101-103, 783-786 p.Article in journal (Refereed)
    Abstract [en]

    Resonant X-ray scattering measurements were performed on CeB6, CeAl, γ-Ce, and α-Ce at various incident-photon energies near the Ce 4d threshold. A pronounced inelastic scattering structure which has 4f character is observed at about 4 eV below the elastic peak. The structure shows a distinct resonant behavior as well as a dependence on the degree of 4f hybridization and can therefore be attributed to charge-transfer excitations to the 4f0 state. The intensity of the elastic peak increases when going from the systems with low Kondo temperature TK to those with high TK which is consistent with a Kondo scale behavior. By analyzing the scattering data, a controversial issue on the validity of a single-impurity Anderson model in heavy-fermion materials is addressed.

  • 6.
    Duda, L.-C.
    et al.
    Uppsala University.
    Schmitt, T.
    Uppsala University.
    Magnuson, Martin
    Uppsala University.
    Forsberg, J.
    Uppsala University.
    Olsson, A.
    Uppsala University.
    Nordgren, J.
    Uppsala University.
    Okada, K.
    Uppsala University.
    Kotani, A.
    Uppsala University.
    Reply to comment by Hüfner on "Resonant Inelastic X-Ray Scattering at the Oxygen K Resonance of NiO: Nonlocal Charge Transfer and Double-Singlet Excitations"2006In: Physical Review Letters, ISSN 0031-9007, Vol. 97, no 269702Article in journal (Other academic)
  • 7.
    Duda, L.-C.
    et al.
    Uppsala University.
    Schmitt, T.
    Uppsala University.
    Magnuson, Martin
    Uppsala University.
    Forsberg, J.
    Uppsala University.
    Olsson, A.
    Uppsala University.
    Nordgren, J.
    Uppsala University.
    Okada, K.
    Okayama University.
    Kotani, A.
    RIKEN/Spring8.
    Resonant Inelastic X-Ray Scattering at the Oxygen K Resonance of NiO: Nonlocal Charge Transfer and Double-Singlet Excitations2006In: Physical Review Letters, ISSN 0031-9007, Vol. 96, no 067402Article in journal (Refereed)
    Abstract [en]

    We report high-resolution polarization-dependent resonant inelastic x-ray scattering (RIXS) at the O K resonance of NiO showing a rich excitation spectrum. We perform multisite Ni6O19 cluster model calculations, revealing that solid state effects are substantial. We identify a nonlocal charge transfer excitation at 4–5 eV and double-singlet creation at 1.75 eV, both exhibiting significant scattering geometry dependence. Apart from an intense band of local charge transfer excitations (above 5 eV) also dd excitations at 1 eV are observed. Finally, we point out that O K RIXS of correlated metal oxides allows a quantitative and consistent determination of the charge transfer energy and the Hund coupling energy JH.

  • 8.
    Duda, L.-C.
    et al.
    Department of Physics,Uppsala University, Uppsala, Sweden.
    Schmitt, T.
    Department of Physics,Uppsala University, Uppsala, Sweden / Swiss Light Source, Paul Scherrer Institute, Switzerland.
    Magnuson, Martin
    Department of Physics,Uppsala University, Uppsala, Sweden.
    Forsberg, J.
    Department of Physics,Uppsala University, Uppsala, Sweden.
    Olsson, A.
    Department of Physics,Uppsala University, Uppsala, Sweden.
    Nordgren, J.
    Department of Physics,Uppsala University, Uppsala, Sweden.
    Okada, K.
    The Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan.
    Kotani, A.
    RIKEN/Spring8,1-1-1 Kouto, Mikazuki-cho, Saya-gun, Hyogo,Japanand / Photon Factory, IMSS, High Energy Accelerator Research Organization,Tsukuba, Ibaragi, Japan .
    Resonant inelastic X-ray scattering at the NiO O K-resonance: non-local charge-transfer and double singlet excitations2007In: MAX-lab: Activity Report 2005-2006 / [ed] U. Johansson, A. Nyberg, R. Nyholm, H. Ullman, Lund: MAX-lab , 2007, 270-271 p.Chapter in book (Other academic)
    Abstract [en]

    NiO is one of the prototypical compounds that has highlighted the importance of correlation effects in transition metal oxides. Core level spectroscopies bear evidence for the highly correlated nature of low energy excitations. For instance, the asymmetry of the Ni2p-line shape has been attributed to non-local charge transfer excitations and multi-site cluster calculations show that solidstate effects generally are appreciable for correlated materials, such as cuprates and high Tc-compounds.....

  • 9.
    Fink, Reinhold F.
    et al.
    Uppsala University.
    Eschner, Annika
    University of Lund.
    Magnuson, Martin
    Uppsala University.
    Björneholm, Olle
    Uppsala University.
    Hjelte, Ingela
    Uppsala University.
    Miron, Catalin
    University of Lund.
    Bässler, Margit
    University of Lund.
    Svensson, Svante
    Uppsala University.
    Novella Piancastelli, Maria
    Uppsala University.
    Sörensen, Stacey L.
    University of Lund.
    Specific production of very long-lived core-excited sulphur atoms by 2p-1s excitation of the OCS molecule followed by ultrafast dissociation2006In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 39, no 12, L269-L275 p.Article in journal (Refereed)
    Abstract [en]

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

  • 10.
    Fink, Reinhold F.
    et al.
    Uppsala University.
    Eschner, Annika
    University of Lund.
    Magnuson, Martin
    Uppsala University.
    Björneholm, Olle
    Uppsala University.
    Hjelte, Ingela
    Uppsala University.
    Miron, Catalin
    University of Lund.
    Bässler, Margit
    University of Lund.
    Svensson, Svante
    Uppsala University.
    Piancastelli, Maria Novella
    Uppsala University.
    Sörensen, Stacey L.
    University of Lund.
    Long-lived highly excited sulphur atoms produced by ultrafast doissociation of 2p-1sigma*-excited OCS molecules2005Report (Other academic)
  • 11.
    Furlan, Andrej
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jansson, Ulf
    Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Magnuson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Structure and bonding in amorphous iron carbide thin films2015In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 27, no 4, 045002- p.Article in journal (Refereed)
    Abstract [en]

    We investigate the amorphous structure, chemical bonding, and electrical properties ofmagnetron sputtered Fe1−xCx (0.21 < x < 0.72) thin films. X-ray, electron diffraction andtransmission electron microscopy show that the Fe1−xCx films are amorphousnanocomposites, consisting of a two-phase domain structure with Fe-rich carbidic FeCy , and acarbon-rich matrix. Pair distribution function analysis indicates a close-range order similar tothose of crystalline Fe3C carbides in all films with additional graphene-like structures at highcarbon content (71.8 at% C). From x-ray photoelectron spectroscopy measurements, we findthat the amorphous carbidic phase has a composition of 15–25 at% carbon that slightlyincreases with total carbon content. X-ray absorption spectra exhibit an increasing number ofunoccupied 3d states and a decreasing number of C 2p states as a function of carbon content.These changes signify a systematic redistribution in orbital occupation due to charge-transfereffects at the domain-size-dependent carbide/matrix interfaces. The four-point proberesistivity of the Fe1−xCx films increases exponentially with carbon content from ∼200μcm(x = 0.21) to ∼1200μcm (x = 0.72), and is found to depend on the total carbon contentrather than the composition of the carbide. Our findings open new possibilities for modifyingthe resistivity of amorphous thin film coatings based on transition metal carbides through thecontrol of amorphous domain structures.

  • 12.
    Furlan, Andrej
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jansson, Ulf
    Uppsala University, Sweden .
    Magnuson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Crystallization characteristics and chemical bonding properties of nickel carbide thin film nanocomposites2014In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 26, no 41, 415501-415512 p.Article in journal (Refereed)
    Abstract [en]

    The crystal structure and chemical bonding of magnetron-sputtering deposited nickel carbide Ni1−xCx (0.05≤x≤0.62) thin films have been investigated by high-resolution x-ray diffraction, transmission electron microscopy, x-ray photoelectron spectroscopy, Raman spectroscopy, and soft x-ray absorption spectroscopy. By using x-ray as well as electron diffraction, we found carbon-containing hcp-Ni (hcp-NiCy phase), instead of the expected rhombohedral-Ni3C. At low carbon content (4.9 at%), the thin film consists of hcp-NiCy nanocrystallites mixed with a smaller amount of fcc-NiCx. The average grain size is about10–20 nm. With the increase of carbon content to 16.3 at%, the film contains single-phase hcp-NiCy nanocrystallites with expanded lattice parameters. With a further increase of carbon content to 38 at%, and 62 at%, the films transform to x-ray amorphous materials with hcp-NiCy and fcc-NiCx nanodomain structures in an amorphous carbon-rich matrix. Raman spectra of carbon indicate dominant sp2 hybridization, consistent with photoelectron spectra that show a decreasing amount of C–Ni phase with increasing carbon content. The Ni 3d–C 2p hybridization in the hexagonal structure gives rise to the salient double-peak structure in Ni 2p soft x-ray absorption spectra at 16.3 at% that changes with carbon content. We also show thatthe resistivity is not only governed by the amount of carbon, but increases by more than a factor of two when the samples transform from crystalline to amorphous.

  • 13.
    Guo, J.-H.
    et al.
    Uppsala University.
    Magnuson, Martin
    Uppsala University.
    Såthe, C
    Uppsala University.
    Nordgren, J.
    Uppsala University.
    Yang, L.
    Luo, Y
    Ågren, H.
    Xing, K.
    Johansson, N.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Daik, R
    Durham University.
    Feast, W. J.
    Durham University.
    How the phenyle rings (benszene) act as builing blocks in conjugated polymers1998Report (Other academic)
  • 14.
    Guo, J.-H.
    et al.
    Department of Physics, Uppsala University, Uppsala, Sweden.
    Magnuson, Martin
    Department of Physics, Uppsala University, Uppsala, Sweden.
    Såthe, C.
    Department of Physics, Uppsala University, Uppsala, Sweden.
    Nordgren, J.
    Department of Physics, Uppsala University, Uppsala, Sweden.
    Yang, L.
    Department of Physics and Measurement Technology, Linköping University, Linköping, Sweden.
    Luo, Y.
    Department of Physics and Measurement Technology, Linköping University, Linköping, Sweden.
    Ågren, H.
    Department of Physics and Measurement Technology, Linköping University, Linköping, Sweden.
    Xing, K.
    Department of Physics and Measurement Technology, Linköping University, Linköping, Sweden.
    Johansson, N.
    Department of Physics and Measurement Technology, Linköping University, Linköping, Sweden.
    Salaneck, William R
    Department of Physics and Measurement Technology, Linköping University, Linköping, Sweden.
    Daik, R.
    IRC in polymer Science and Technology, Durham University, Durham, UK.
    Feast, W. J.
    IRC in polymer Science and Technology, Durham University, Durham, UK.
    How the phenyle rings (benzene) act as building blocks in pi conjugated polymers1998In: Advanced Light Source: Compendium of User Abstractsand Technical Reports1993-1996 / [ed] Deborah J. Dixon, jane Cross, Kathryn Devereaux, and Annette Greiner, Berkeley: Ernest Orlando Lawrence Berkeley National Laboratory, University of California Berkeley, California, USA , 1998, 129-132 p.Chapter in book (Other academic)
    Abstract [en]

    Organic conjugated polymers have the electronic structure of semiconductors and can be doped to become good conductors (1). Conjugated polymers are now used as active materials in a wide variety of prototype applications such as light emitting diodes [2] and organic transistors [3,4]. Most of the interesting chemistry and physics of conjugated polymers is associated with the details of the electronic structure at the valence and conduction band edges and, in this connection, various electron spectroscopies can be used as tools for diagnosis of the relevant electronic and geometric properties....

  • 15.
    Guo, J.-H.
    et al.
    Uppsala University.
    Magnuson, Martin
    Uppsala University.
    Såthe, C.
    Uppsala University.
    Nordgren, J.
    Uppsala University.
    Yang, L.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Luo, Y.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Ågren, H.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Xing, K. Z.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Johansson, N.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Daik, R.
    Durham University.
    Feast, W. J.
    Durham University.
    Resonant and nonresonant x-ray scattering spectra of some poly(phenylenevinylene)s1998In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 108, no 14, 5990-5996 p.Article in journal (Refereed)
    Abstract [en]

    The electronic structure of some poly(phenylenevinylene)s have been investigated by resonant and nonresonant x-ray inelastic scattering spectroscopies. The nonresonant as well as all resonant spectra for each polymer demonstrate benzene-like features, indicating a local character of the x-ray emission in which the phenyl ring acts as a building block. Theoretical simulations of x-ray energies and intensities taking the repeat unit as a model molecule of the polymer agree with the experimental spectra fairly well. The edges of the occupied bands have been identified in the nonresonant spectra of each polymer. By subtracting the emission energy of the highest occupied molecular orbital in the nonresonant spectrum from the core excitation energy in the resonant spectrum an alternative way to determine the optical band gap is obtained. As for free benzene the outer π band in the polymer spectra show a depletion of the emission going from the nonresonant to the resonant x-ray emission spectra. It is demonstrated that this transition, which is strictly symmetry forbidden for free benzene, becomes effectively forbidden in the polymer case as a result of strong interference effects, and it is argued that this is the general case for resonant x-ray emission of conjugated polymers as far as the frozen orbital approximation holds.

  • 16.
    Hague, C F
    et al.
    Laboratoire de Chimie Physique-Matière et Rayonnement, Univ P. et M. Curie, Paris, France.
    Journel, L
    Laboratoire de Chimie Physique-Matière et Rayonnement, Univ P. et M. Curie, Paris, France.
    Magnuson, Martin
    Laboratoire de Chimie Physique-Matière et Rayonnement, Univ P. et M. Curie, Paris, France.
    Mariot, J-M
    Laboratoire de Chimie Physique-Matière et Rayonnement, Univ P. et M. Curie, Paris, France.
    Sacchi, M
    LURE, BP 34, F-91898 Orsay Cedex, France.
    Gautier-Soyer, M
    SRSIM, DRECAM, CEA, Bât 462, CE Saclay, F-91191 Gif-sur-Yvette, France.
    Gota, S
    SRSIM, DRECAM, CEA, Bât 462, CE Saclay, F-91191 Gif-sur-Yvette, France.
    Ferrimagnetic order in thin-film Fe3O4 studied by resonant inelastic X-ray scattering2000Report (Other academic)
    Abstract [en]

    We have set out to use the ID21 microfocusing beamline to perform resonant inelastic x-ray scattering (RIXS) experiments on magnetic materials. For the first tests and experiments we start off with Fe oxide thin films of potential interest in new technical applications. Of main interest are thin films of Fe3O4 epitaxially grown on alumina. Note that RIXS is particularly well adapted to experiments involving samples on insulating substrates (no charging effects) prepared ex-situ (bulk sensitivity) which can be magnetized (all-photons experiment)....

  • 17.
    Hahlin, Maria
    et al.
    Uppsala University.
    Odelius, M
    Stockholm University.
    Magnuson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Johansson, Erik
    Uppsala University.
    Plogmaker, S
    Uppsala University.
    Hagberg, D
    Royal Institute of Technology.
    Sun, L
    Royal Institute of Technology.
    Siegbahn, H
    Royal Institute of Technology.
    Rensmo, H
    Uppsala University.
    Mapping the frontier electronic structures of triphenylamine basedorganic dyes at TiO2 interfaces2011In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 13, no 8, 3534-3546 p.Article in journal (Refereed)
    Abstract [en]

    The frontier electronic structures of a series of organic dye molecules containing a triphenylaminemoiety, a thiophene moiety and a cyanoacrylic acid moiety have been investigated byphotoelectron spectroscopy (PES), X-ray absorption spectroscopy (XAS), X-ray emissionspectroscopy (XES) and resonant photoelectron spectroscopy (RPES). The experimental resultswere compared to electronic structure calculations on the molecules, which are used to confirmand enrich the assignment of the spectra. The approach allows us to experimentally measure andinterpret the basic valence energy level structure in the dye, including the highest occupied energylevel and how it depends on the interaction between the different units. Based on N 1s X-rayabsorption and emission spectra we also obtain insight into the structure of the excited states,the molecular orbital composition and dynamics. Together the results provide an experimentallydetermined energy level map useful in the design of these types of materials. Included are alsoresults indicating femtosecond charge redistribution at the dye/TiO2 interface.

  • 18.
    Halim, Joseph
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology. Department of Materials Science & Engineering and 3A.J. Drexel Nanotechnology Institute, Drexel University, Philadelphia, USA.
    Cook, Kevin M.
    University of Penn, PA 19104 USA Drexel University, PA 19104 USA .
    Näslund, Lars-Åke
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Magnuson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology. University of Penn, PA 19104 USA .
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Gogotsi, Yury
    University of Penn, PA 19104 USA Drexel University, PA 19104 USA .
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Barsoum, Michel W.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology. Department of Materials Science & Engineering, Drexel University, Philadelphia, USA.
    X-ray Photoelectron Spectroscopy Characterization of Two-Dimensional Titanium Metal Carbides (MXenes)2014Manuscript (preprint) (Other academic)
    Abstract [en]

    Herein, we report X-ray Photoelectron Spectroscopy (XPS) analysis for cold pressed exfoliated 2D nanocrystals of transition metal carbides, MXenes. MXenes are a recently discovered family of 2D materials produced by selective chemical etching of the A element from MAX phases which are ternary metal carbides and nitrides. The latter has the formula of Mn+1AXn, where M is an early transition metal, A is an A-group element, and X is C and/or N. This study is a comparison between two MXenes, Ti3C2Tx and Ti2CTx, where Tx stands for surface termination groups such as –O, –OH, and –F. Ti3C2Tx and Ti2CTx were prepared by immersion of Ti3AlC2 and Ti2AlC powders in 50% conc. HF. A thorough XPS analysis was performed through peak fitting of high resolution XPS spectra and valence band, VB, spectra analysis. The effect of Ar sputtering as well as the number of layers n was the primarily interest of this study. According to the peak fitting analysis, both phases contain the following species, Ti–C, C–C, Ti–F, Ti–O and Ti–OH resulting in the following chemical formulas: Ti3C2(OH)x(O)y(F)z and Ti2C(OH)x(O)y(F)z. Comparing the VB spectra with the DOS calculations show the valance band spectra is actually a mixture of MXene with various terminations of OH, O and F. Before Ar+ sputtering both phases show a large percentage of fluorinated-TiO2 which is due to MXene surface oxidation as well as CHx, C-O and COO groups arising from either surface contaminations or due to drying the etched powders in ethanol after washing the powder of the HF acid. According to the VB spectra, it is shown that the fluorinated TiO2 is actually a mixture of anatase and rutile. The number of layers, n, also plays a role; the lower n, the more the MXene is prone to oxidation.

  • 19.
    Karis, O.
    et al.
    Uppsala University.
    Magnuson, Martin
    Uppsala University.
    Wiell, T.
    Uppsala University.
    Weinelt, M.
    Uppsala University.
    Wassdahl, N.
    Uppsala University.
    Nilsson, A.
    Uppsala University.
    Mårtensson, N.
    Uppsala University.
    Holmström, E.
    Uppsala University.
    Niklasson, A. M. N.
    Uppsala University.
    Eriksson, O.
    Uppsala University.
    Johansson, B.
    Uppsala University.
    Probing surface states of Cu/Ni thin films using x-ray absorption spectroscopy2001In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, Vol. 63, no 113401Article in journal (Refereed)
    Abstract [en]

    Surface and interface properties of Cu thin films (1–4 monolayers) deposited on Ni(100) have been extracted by means of x-ray absorption spectroscopy and analyzed in combination with ab initio density-functional calculations. An unoccupied Cu surface state is identified in an x-ray absorption spectra and studied as a function of film thickness. Experimental data is supported by calculations of the layer-resolved density of states and the results from this combined theoretical-experimental effort show that the surface state is almost entirely located on the atomic layer closest to the vacuum. Our results also indicate strong hybridization between unoccupied states at the Cu/Ni interface boundary.

  • 20.
    Karis, O.
    et al.
    Uppsala University.
    Magnuson, Martin
    Université Pierre et Marie Curie, Paris.
    Wiell, T
    Uppsala University.
    Weinelt, M.
    Uppsala University.
    Wassdahl, N.
    Uppsala University.
    Nilsson, A.
    Uppsala University.
    Mårtensson, N.
    Uppsala University.
    Holmström, E.
    Uppsala University.
    Niklasson, A. M. N.
    Los Alamos National Laboratory, Los Alamos, New Mexico.
    Eriksson, Olle
    Uppsala University.
    Observation of short- and long-range hybridization of a buried Cu monolayer in Ni2000In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 62, no 24, R16239-R16242 p.Article in journal (Refereed)
    Abstract [en]

    The electronic structure of a Cu monolayer buried in Ni fcc(100) is studied by means of x-ray emission and absorption spectroscopies in combination with first principles calculations. The local character of the x-ray probes allows us to investigate changes in the chemical interaction for these ultrathin film systems. In comparison to bulk Cu, the occupied d states of a buried Cu monolayer, as mapped in the x-ray emission spectrum, remain mostly unaltered. The absorption spectrum on the other hand shows that the empty states of the buried Cu monolayer are modified, and instead resemble the unoccupied electronic density of bulk Ni. These findings agree well with our first principle electronic structure calculations and the results are interpreted in terms of short- and long-range hybridization.

  • 21.
    Kurmaev, E. Z.
    et al.
    Russian Academy of Sciences - Ural Division, Yekaterinburg.
    Katsnelson, M. I.
    Russian Academy of Sciences - Ural Division, Yekaterinburg.
    Moeves, Alexander
    University of Saskatchewan, Saskatoon, Canada .
    Magnuson, Martin
    Uppsala University.
    Guo, J.-H.
    Uppsala University.
    Butorin, S. M.
    Uppsala University.
    Nordgren, J.
    Uppsala University.
    Ederer, D. L.
    Tulane University, New Orleans.
    Iwami, M.
    Okayama University.
    Spectroscopic observation of polaron-lattice band structure in the conducting polymer polyaniline2001In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 13, no 17, 3907-3912 p.Article in journal (Refereed)
    Abstract [en]

    We present the results of soft x-ray emission measurements for undoped and protonated polyemeraldine. We show that the polaron-lattice band structure fully accounts for the observed x-ray transitions. A finite spectral intensity of C Kα and N Kα XES is observed at the Fermi level for protonated polyemeraldine, supporting the applicability of the polaronic-metal model for highly conducting polymers.

  • 22.
    Magnuson, M.
    et al.
    Uppsala University.
    Nilsson, A.
    Uppsala University.
    Weinelt, M.
    Uppsala University.
    N. Mårtensson, N.
    Uppsala University.
    Angular-dependent resonant-photoemission processes at the 2p thresholds in nickel metal1999In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 60, 2436-2440 p.Article in journal (Refereed)
    Abstract [en]

    Angle-resolved valence-band resonant-photoemission of nickel metal has been measured close to the 2p core-level thresholds with synchrotron radiation. The well-known 6-eV correlation satellite has an intensity enhancement of about two orders of magnitude at resonance. The angular dependence of the photoemission intensity has been studied as function of photon energy and provides unambiguous evidence for interference effects all the way up to the resonance maximum. The observation of different angular asymmetries, β, for the valence band and the satellite is discussed in connection to the origin of the resonant-photoemission process and the character of the satellite.

  • 23.
    Magnuson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Department of Physics, Uppsala University, Box 530, S-75121 Uppsala, Sweden.
    An Electron Beam Heated Evaporation Source1994Report (Other academic)
    Abstract [en]

    An electron beam evaporator has been assembled, tested and used for deposition of thin nickel films. Flux and deposition rates has been measured with an oscillating quartz crystal monitor (QCM), an ion sensor wire, and visible deposition on a mirror on front of the evaporator. A thin nickel rod of 2 mm diameter was found to improve the pressure in comparison to a 6-mm nickel rod. The flux was typically 3-4 Angstroms per minute during the test, but other flux rates can easily be achieved by changing the filament current and the acceleration voltage.

  • 24.
    Magnuson, Martin
    Department of Physics, Uppsala University.
    Electronic structure investigation of MAX-phases by soft x-ray emission spectroscopy2007In: MRS Online Proceedings Library, Volume 1023 / [ed] E. Ivers-Tiffee and S. Barnett, 2007Conference paper (Refereed)
    Abstract [en]

    The electronic structure of nanolaminate Ti2AlC and Ti2AlN thin films, so-called MAX-phases, were investigated by soft X-ray emission spectroscopy. These nanolaminated carbide and nitride compounds represent a class of layered materials with a combination of properties from both metals and ceramics. The bulk-sensitive soft X-ray emission technique is particularly useful for detecting detailed electronic structure information about internal monolayers and interfaces. The Ti-Al bonding is manifested by a pronounced peak in the Ti L-emission of Ti2AlC and Ti2AlN that is not present in the binary TiC system. The spectral shape of Al L-emission in the MAX-phase is strongly modified in comparison to metallic Al. By replacing or partly exchanging C with N, a change of the electron population can be achieved causing a change of covalent bonding between the laminated layers, which enables control of the material properties.

  • 25.
    Magnuson, Martin
    Uppsala University.
    Electronic Structure Studies Using Resonant X-ray and Photemission Spectroscopy1999Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis addresses the electronic structure of molecules and solids using resonant X-ray emission and photoemission spectroscopy. The use of monochromatic synchrotron radiation and the improved performance of the instrumentation have opened up the possibility of detailed analyses of the response of the electronic systems under interaction with X-rays. The experimental studies are accompanied by numerical ab initio calculations in the formalism of resonant inelastic scattering. The energy selectivity has made it possible for the first time to study how the chemical bonds in a molecule break up during resonant inelastic X-ray scattering. In the conjugated polymer systems, the element selectivity of the X-ray emission process made it possible to probe the different atomic elements separately. The X-ray emission technique proved to be useful for extracting isomeric information, and for measuring the change in the valence levels at different degrees of doping. In this thesis, spectral satellite features in transition metals were thoroughly investigated for various excitation energies around a core-level threshold. By measuring the relative spectral intensity of the satellites it was possible to extract information on the partial core-level widths. Using the nickel metal system as an example, it was shown that it is possible to probe the different core-excited states close toshake-up thresholds by measuring the relative spectral intensity variation of the Auger emission.Resonant photoemission measurements showed unambiguous evidence of interference effects. Theseeffects were also thoroughly probed using angle-dependent measurements. The combination of X-rayemission and absorption were useful for studying buried layers and interfaces due to the appreciable penetration depth of soft X-rays. X-ray scattering was further found to be useful for studying low-energy excited states of rare earth metallic compounds and transition metal oxides.

    List of papers
    1. Low-energy d-d excitations in MnO studied by resonant x-ray fluorescence spectroscopy
    Open this publication in new window or tab >>Low-energy d-d excitations in MnO studied by resonant x-ray fluorescence spectroscopy
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    1996 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, Vol. 54, 4405-4408 p.Article in journal (Refereed) Published
    Abstract [en]

    We measured the Mn Lα,β x-ray fluorescence spectra of MnO excited by selected photon energies near the L2,3 absorption edges. The resulting resonant inelastic x-ray scattering spectra probe low-lying electronic excited states, due to dd and charge-transfer excitations. Using a two-step model and a purely atomic approximation, we reproduce both energies and varying intensities of dd excitations relative to the electronic recombination peak. Our results show that strongly varying line shapes in resonant x-ray emission need not be due to channel interference effects.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-17475 (URN)10.1103/PhysRevB.54.4405 (DOI)
    Note
    Original Publication:S. M. Butorin, J.-H. Guo, Martin Magnuson, P. Kuiper and J. Nordgren, Low-energy d-d excitations in MnO studied by resonant x-ray fluorescence spectroscopy, 1996, Physical Review B. Condensed Matter and Materials Physics, (54), 4405-4408.http://dx.doi.org/10.1103/PhysRevB.54.4405Copyright: American Physical Societyhttp://www.aps.org/Available from: 2009-03-26 Created: 2009-03-25 Last updated: 2013-10-02Bibliographically approved
    2. Resonant inelastic soft-x-ray scattering from valence-band excitations in 3d0 compounds
    Open this publication in new window or tab >>Resonant inelastic soft-x-ray scattering from valence-band excitations in 3d0 compounds
    1997 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, Vol. 55, 4242-4249 p.Article in journal (Refereed) Published
    Abstract [en]

    Ti and Mn Lα,Β x-ray fluorescence spectra of FeTiO3 and KMnO4 were measured with monochromatic photon excitation on selected energies across the L2,3 absorption edges. The resulting inelastic x-ray-scattering structures and their changes with varying excitation energies are interpreted within the framework of a localized, many-body approach based on the Anderson impurity model, where the radiative process is characterized by transitions to low-energy interionic-charge-transfer excited states. Sweeping the excitation energy through the metal 2p threshold enhances the fluorescence transitions to the antibonding states pushed out of the band of continuous states due to strong metal 3d–ligand 2p hybridization and matching the low-photon-energy satellites in the spectra. Based on the energy position of these charge-transfer satellites with respect to the recombination peak the effective metal 3d–ligand 2p hybridization strength in the ground state of the system can be estimated directly from the experiment.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-17474 (URN)10.1103/PhysRevB.55.4242 (DOI)
    Note
    Original Publication:S. M. Butorin, J.-H. Guo, Martin Magnuson and J. Nordgren, Resonant inelastic soft-x-ray scattering from valence-band excitations in 3d0 compounds, 1997, Physical Review B. Condensed Matter and Materials Physics, (55), 4242-4249.http://dx.doi.org/10.1103/PhysRevB.55.4242Copyright: American Physical Societyhttp://www.aps.org/Available from: 2009-03-26 Created: 2009-03-25 Last updated: 2013-10-02Bibliographically approved
    3. Resonant inelastic soft X-ray scattering at the 4d edge of Ce-based heavy fermion materials
    Open this publication in new window or tab >>Resonant inelastic soft X-ray scattering at the 4d edge of Ce-based heavy fermion materials
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    1999 (English)In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, Vol. 101-103, 783-786 p.Article in journal (Refereed) Published
    Abstract [en]

    Resonant X-ray scattering measurements were performed on CeB6, CeAl, γ-Ce, and α-Ce at various incident-photon energies near the Ce 4d threshold. A pronounced inelastic scattering structure which has 4f character is observed at about 4 eV below the elastic peak. The structure shows a distinct resonant behavior as well as a dependence on the degree of 4f hybridization and can therefore be attributed to charge-transfer excitations to the 4f0 state. The intensity of the elastic peak increases when going from the systems with low Kondo temperature TK to those with high TK which is consistent with a Kondo scale behavior. By analyzing the scattering data, a controversial issue on the validity of a single-impurity Anderson model in heavy-fermion materials is addressed.

    Keyword
    Resonant soft-X-ray scattering; Ce-based heavy-fermion systems; Charge-transfer excitations; X-ray absorption
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-54982 (URN)10.1016/S0368-2048(98)00369-7 (DOI)
    Available from: 2010-04-26 Created: 2010-04-26 Last updated: 2014-11-13Bibliographically approved
    4. Resonant and nonresonant x-ray scattering spectra of some poly(phenylenevinylene)s
    Open this publication in new window or tab >>Resonant and nonresonant x-ray scattering spectra of some poly(phenylenevinylene)s
    Show others...
    1998 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 108, no 14, 5990-5996 p.Article in journal (Refereed) Published
    Abstract [en]

    The electronic structure of some poly(phenylenevinylene)s have been investigated by resonant and nonresonant x-ray inelastic scattering spectroscopies. The nonresonant as well as all resonant spectra for each polymer demonstrate benzene-like features, indicating a local character of the x-ray emission in which the phenyl ring acts as a building block. Theoretical simulations of x-ray energies and intensities taking the repeat unit as a model molecule of the polymer agree with the experimental spectra fairly well. The edges of the occupied bands have been identified in the nonresonant spectra of each polymer. By subtracting the emission energy of the highest occupied molecular orbital in the nonresonant spectrum from the core excitation energy in the resonant spectrum an alternative way to determine the optical band gap is obtained. As for free benzene the outer π band in the polymer spectra show a depletion of the emission going from the nonresonant to the resonant x-ray emission spectra. It is demonstrated that this transition, which is strictly symmetry forbidden for free benzene, becomes effectively forbidden in the polymer case as a result of strong interference effects, and it is argued that this is the general case for resonant x-ray emission of conjugated polymers as far as the frozen orbital approximation holds.

    Keyword
    Polymers, elastomers, and plastics, X-ray emission spectra and fluorescence, Electron density of states and band structure of crystalline solids
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-54988 (URN)10.1063/1.476011 (DOI)
    Available from: 2010-04-26 Created: 2010-04-26 Last updated: 2013-10-02
    5. Probing surface states of Cu/Ni thin films using x-ray absorption spectroscopy
    Open this publication in new window or tab >>Probing surface states of Cu/Ni thin films using x-ray absorption spectroscopy
    Show others...
    2001 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, Vol. 63, no 113401Article in journal (Refereed) Published
    Abstract [en]

    Surface and interface properties of Cu thin films (1–4 monolayers) deposited on Ni(100) have been extracted by means of x-ray absorption spectroscopy and analyzed in combination with ab initio density-functional calculations. An unoccupied Cu surface state is identified in an x-ray absorption spectra and studied as a function of film thickness. Experimental data is supported by calculations of the layer-resolved density of states and the results from this combined theoretical-experimental effort show that the surface state is almost entirely located on the atomic layer closest to the vacuum. Our results also indicate strong hybridization between unoccupied states at the Cu/Ni interface boundary.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-17468 (URN)10.1103/PhysRevB.63.113401 (DOI)
    Note
    Original Publication:O. Karis, Martin Magnuson, T. Wiell, M. Weinelt, N. Wassdahl, A. Nilsson, N. Mårtensson, E. Holmström, A. M. N. Niklasson, O. Eriksson and B. Johansson, Probing surface states of Cu/Ni thin films using x-ray absorption spectroscopy, 2001, Physical Review B. Condensed Matter and Materials Physics, (63), 113401.http://dx.doi.org/10.1103/PhysRevB.63.113401Copyright: American Physical Societyhttp://www.aps.org/Available from: 2009-03-26 Created: 2009-03-25 Last updated: 2013-10-02Bibliographically approved
    6. Observation of short- and long-range hybridization of a buried Cu monolayer in Ni
    Open this publication in new window or tab >>Observation of short- and long-range hybridization of a buried Cu monolayer in Ni
    Show others...
    2000 (English)In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 62, no 24, R16239-R16242 p.Article in journal (Refereed) Published
    Abstract [en]

    The electronic structure of a Cu monolayer buried in Ni fcc(100) is studied by means of x-ray emission and absorption spectroscopies in combination with first principles calculations. The local character of the x-ray probes allows us to investigate changes in the chemical interaction for these ultrathin film systems. In comparison to bulk Cu, the occupied d states of a buried Cu monolayer, as mapped in the x-ray emission spectrum, remain mostly unaltered. The absorption spectrum on the other hand shows that the empty states of the buried Cu monolayer are modified, and instead resemble the unoccupied electronic density of bulk Ni. These findings agree well with our first principle electronic structure calculations and the results are interpreted in terms of short- and long-range hybridization.

    Keyword
    X-ray absorption spectra, X-ray emission spectra and fluorescence, Methods of electronic structure calculations
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-54981 (URN)10.1103/PhysRevB.62.R16239 (DOI)
    Note
    Original Publication: O. Karis, Martin Magnuson, T Wiell, M. Weinelt, N. Wassdahl, A. Nilsson, N. Mårtensson, E. Holmström, A. M. N. Niklasson and Olle Eriksson, Observation of short- and long-range hybridization of a buried Cu monolayer in Ni, 2000, Physical Review B Condensed Matter, (62), 24, R16239-R16242. http://dx.doi.org/10.1103/PhysRevB.62.R16239 Copyright: American Physical Society http://www.aps.org/ Available from: 2010-04-26 Created: 2010-04-26 Last updated: 2013-10-02
    7. Angular-dependent resonant-photoemission processes at the 2p thresholds in nickel metal
    Open this publication in new window or tab >>Angular-dependent resonant-photoemission processes at the 2p thresholds in nickel metal
    1999 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 60, 2436-2440 p.Article in journal (Refereed) Published
    Abstract [en]

    Angle-resolved valence-band resonant-photoemission of nickel metal has been measured close to the 2p core-level thresholds with synchrotron radiation. The well-known 6-eV correlation satellite has an intensity enhancement of about two orders of magnitude at resonance. The angular dependence of the photoemission intensity has been studied as function of photon energy and provides unambiguous evidence for interference effects all the way up to the resonance maximum. The observation of different angular asymmetries, β, for the valence band and the satellite is discussed in connection to the origin of the resonant-photoemission process and the character of the satellite.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-17469 (URN)10.1103/PhysRevB.60.2436 (DOI)
    Note

    Original Publication:M. Magnuson, A. Nilsson, M. Weinelt, N. and N. Mårtensson, Angular-dependent resonant-photoemission processes at the 2p thresholds in nickel metal, 1999, Physical Review B. Condensed Matter and Materials Physics, (60), 2436-2440.http://dx.doi.org/10.1103/PhysRevB.60.2436Copyright: American Physical Societyhttp://www.aps.org/

    Available from: 2009-03-26 Created: 2009-03-25 Last updated: 2013-10-02Bibliographically approved
    8. Electronic-structure investigation of CeB6 by means of soft-x-ray scattering
    Open this publication in new window or tab >>Electronic-structure investigation of CeB6 by means of soft-x-ray scattering
    Show others...
    2001 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 63, no 075101Article in journal (Refereed) Published
    Abstract [en]

    The electronic structure of the heavy fermion compound CeB6 is probed by resonant inelastic soft-x-ray scattering using photon energies across the Ce 3d and 4d absorption edges. The hybridization between the localized 4f orbitals and the delocalized valence-band states is studied by identifying the different spectral contributions from inelastic Raman scattering and normal fluorescence. Pronounced energy-loss structures are observed below the elastic peak at both the 3d and 4d thresholds. The origin and character of the inelastic scattering structures are discussed in terms of charge-transfer excitations in connection to the dipole allowed transitions with 4f character. Calculations within the single-impurity Anderson model with full multiplet effects are found to yield consistent spectral functions to the experimental data.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-17467 (URN)10.1103/PhysRevB.63.075101 (DOI)
    Note

    Original Publication:Martin Magnuson, S. M. Butorin, J.-H. Guo, A. Agui, J. Nordgren, H. Ogasawara, A. Kotani, T. Takahashi and S. Kunii, Electronic-structure investigation of CeB6 by means of soft-x-ray scattering, 2001, Physical Review B. Condensed Matter and Materials Physics, (63), 075101.http://dx.doi.org/10.1103/PhysRevB.63.075101Copyright: American Physical Societyhttp://www.aps.org/

    Available from: 2009-03-26 Created: 2009-03-25 Last updated: 2013-10-02Bibliographically approved
    9. Competition between decay and dissociation of core-excited carbonyl sulfide studied by x-ray scattering
    Open this publication in new window or tab >>Competition between decay and dissociation of core-excited carbonyl sulfide studied by x-ray scattering
    Show others...
    1999 (English)In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 59, 4281-4287 p.Article in journal (Refereed) Published
    Abstract [en]

    We show evidence of dissociation during resonant inelastic soft x-ray scattering. Carbon and oxygen K-shell and sulfur L-shell resonant and nonresonant x-ray emission spectra were measured using monochromatic synchrotron radiation for excitation and ionization. After sulfur L2,3→π*, σ* excitation, atomic lines are observed in the emission spectra as a consequence of competition between de-excitation and dissociation. In contrast the carbon and oxygen spectra show weaker line-shape variations and no atomic lines. The spectra are compared to results from ab initio calculations. The discussion of the dissociation paths is based on calculated potential energy surfaces and atomic transition energies.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-17470 (URN)10.1103/PhysRevA.59.4281 (DOI)
    Note

    Original Publication: Martin Magnuson, J. Guo, C. Såthe, J.-E. Rubensson, J. Nordgren, P. Glans, L. Yang, P. Sałek and H. Ågren, Competition between decay and dissociation of core-excited carbonyl sulfide studied by x-ray scattering, 1999, Physical Review A. Atomic, Molecular, and Optical Physics, (59), 4281-4287. http://dx.doi.org/10.1103/PhysRevA.59.4281 Copyright: American Physical Society http://www.aps.org/

    Available from: 2009-06-08 Created: 2009-03-25 Last updated: 2013-10-02Bibliographically approved
    10. The electronic structure of polyaniline and doped phases studied by soft X-ray absorption and emission spectroscopies
    Open this publication in new window or tab >>The electronic structure of polyaniline and doped phases studied by soft X-ray absorption and emission spectroscopies
    Show others...
    1999 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 111, no 10, 4756-4761 p.Article in journal (Refereed) Published
    Abstract [en]

    The electronic structure of the conjugated polymer, polyaniline, has been studied by resonant and nonresonant soft x-ray emission spectroscopy using synchrotron radiation for the excitation. The measurements were made on polyaniline and a few doped (protonated) phases for both the carbon and nitrogen contents. The resonant x-ray emission spectra show depletion of the π electron bands due to the selective excitation which enhances the effect of symmetry selection rules. The valence band structures in the x-ray emission spectra attributed to the π bands show unambiguous changes of the electronic structure upon protonation. By comparing to x-ray absorption measurements, the chemical bonding and electronic configuration is characterized.

    Keyword
    Polymers and organic compounds, X-ray absorption spectra, X-ray emission spectra and fluorescence
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-54983 (URN)10.1063/1.479238 (DOI)
    Available from: 2010-04-26 Created: 2010-04-26 Last updated: 2013-10-02
    11. X-ray fluorescence spectra of metals excited below threshold
    Open this publication in new window or tab >>X-ray fluorescence spectra of metals excited below threshold
    Show others...
    2003 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 68, no 045119Article in journal (Refereed) Published
    Abstract [en]

    X-ray scattering spectra of Cu and Ni metals have been measured using monochromatic synchrotron radiation tuned from far above to more than 10 eV below threshold. Energy conservation in the scattering process is found to be sufficient to explain the modulation of the spectral shape, neglecting momentum conservation and channel interference. At excitation energies close to and above threshold, the emission spectra map the occupied local partial density of states. For the subthreshold excitations, the high-energy flank of the inelastic scattering exhibits a Raman-type linear dispersion, and an asymmetric low-energy tail develops. For excitation far below threshold the emission spectra are proportional to a convolution of the occupied and unoccupied local partial densities of states.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-17414 (URN)10.1103/PhysRevB.68.045119 (DOI)
    Note

    Original Publication:Martin Magnuson, J.-E. Rubensson, A. Föhlisch, N. Wassdahl, A. Nilsson and N. Mårtensson, X-ray fluorescence spectra of metals excited below threshold, 2003, Physical Review B. Condensed Matter and Materials Physics, (68), 045119.http://dx.doi.org/10.1103/PhysRevB.68.045119Copyright: American Physical Societyhttp://www.aps.org/

    Available from: 2009-03-23 Created: 2009-03-23 Last updated: 2013-10-02Bibliographically approved
    12. Resonant Auger spectroscopy at the L2,3 shake-up thresholds as a probe of electron correlation effects in nickel
    Open this publication in new window or tab >>Resonant Auger spectroscopy at the L2,3 shake-up thresholds as a probe of electron correlation effects in nickel
    Show others...
    1998 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 58, 3677-3681 p.Article in journal (Refereed) Published
    Abstract [en]

    The excitation energy dependence of the three-hole satellites in the L3-M45M45 and L2-M45M45 Auger spectra of nickel metal has been measured using synchrotron radiation. The satellite behavior in the nonradiative emission spectra at the L3 and L2 thresholds is compared and the influence of the Coster-Kronig channel explored. The three-hole satellite intensity at the L3 Auger emission line reveals a peak structure at 5 eV above the L3 threshold attributed to resonant processes at the 2p53d9 shake-up threshold. This is discussed in connection with the 6-eV feature in the x-ray-absorption spectrum.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-17471 (URN)10.1103/PhysRevB.58.3677 (DOI)
    Note

    Original Publication:Martin Magnuson, N. Wassdahl, A. Nilsson, A. Föhlisch, J. Nordgren and N. Mårtensson, Resonant Auger spectroscopy at the L2,3 shake-up thresholds as a probe of electron correlation effects in nickel, 1998, Physical Review B. Condensed Matter and Materials Physics, (58), 3677-3681.http://dx.doi.org/10.1103/PhysRevB.58.3677Copyright: American Physical Societyhttp://www.aps.org/

    Available from: 2009-03-26 Created: 2009-03-25 Last updated: 2013-10-02Bibliographically approved
    13. Energy dependence of Cu L2,3 satellites using synchrotron excited x-ray-emission spectroscopy
    Open this publication in new window or tab >>Energy dependence of Cu L2,3 satellites using synchrotron excited x-ray-emission spectroscopy
    1997 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 56, 12238-12242 p.Article in journal (Refereed) Published
    Abstract [en]

    The L2,3 x-ray emission of Cu metal has been measured using monochromatic synchrotron radiation. The self-absorption effect in the spectra is shown to be very small in our experimental geometry. From the quantitative analysis of spectra recorded at different excitation energies, the L3/L2 emission intensity ratio and the partial Auger width are extracted. High-energy satellite features on the L3 emission line are separated by a subtraction procedure. The satellite intensity is found to be slowly increasing for excitation energies between the L3, L2, and L1 core-level thresholds due to shake-up and shake-off transitions. As the excitation energy passes the L2 threshold, a step of rapidly increasing satellite intensity of the L3 emission is found due to additional Coster-Kronig processes.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-17472 (URN)10.1103/PhysRevB.56.12238 (DOI)
    Note

    Original Publication:Martin Magnuson, N. Wassdahl and J. Nordgren, Energy dependence of Cu L2,3 satellites using synchrotron excited x-ray-emission spectroscopy, 1997, Physical Review B. Condensed Matter and Materials Physics, (56), 12238-12242.http://dx.doi.org/10.1103/PhysRevB.56.12238Copyright: American Physical Societyhttp://www.aps.org/

    Available from: 2009-03-26 Created: 2009-03-25 Last updated: 2013-10-02Bibliographically approved
    14. The electronic structure of poly(pyridine-2,5-diyl) investigated by soft X-ray absorption and emission spectroscopies
    Open this publication in new window or tab >>The electronic structure of poly(pyridine-2,5-diyl) investigated by soft X-ray absorption and emission spectroscopies
    Show others...
    1998 (English)In: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 237, no 3, 295-304 p.Article in journal (Refereed) Published
    Abstract [en]

    The electronic structure of the poly-pyridine conjugated polymer has been investigated by resonant and non-resonant inelastic X-ray scattering and X-ray absorption spectroscopies using synchrotron radiation. The measurements were made for both the carbon and nitrogen contents of the polymer. The analysis of the spectra has been carried out in comparison with molecular orbital calculations taking the repeat-unit cell as a model molecule of the polymer chain. The simulations indicate no significant differences in the absorption and in the non-resonant X-ray scattering spectra for the different isomeric geometries, while some isomeric dependence of the resonant spectra is predicted. The resonant emission spectra show depletion of the electron bands in line with symmetry selection and momentum conservation rules. The effect is most visual for the carbon spectra; the nitrogen spectra are dominated by lone pair n orbital emission of symmetry and are less frequency dependent.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-54986 (URN)10.1016/S0301-0104(98)00262-6 (DOI)
    Available from: 2010-04-26 Created: 2010-04-26 Last updated: 2013-10-02
    15. Resonant inelastic soft X-ray scattering spectra at the nitrogen and carbon K-edges of poly(pyridine-2,5-diyl)
    Open this publication in new window or tab >>Resonant inelastic soft X-ray scattering spectra at the nitrogen and carbon K-edges of poly(pyridine-2,5-diyl)
    Show others...
    1999 (English)In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, Vol. 101-103, 573-578 p.Article in journal (Refereed) Published
    Abstract [en]

    Resonant inelastic scattering measurements of the conjugated polymer, poly(pyridine-2,5-diyl) have been performed at the nitrogen and carbon K-edges using synchrotron radiation. For comparison, molecular orbital calculations of the spectra have been carried out with the repeat unit as a model molecule of the polymer chain. The resonant emission spectra show depletion of the π electron bands which is consistent with symmetry selection and momentum conservation rules. The depletion is most obvious in the resonant inelastic scattering spectra of carbon while the nitrogen spectra are dominated by lone pair n orbital emission of σ symmetry and are less excitation energy dependent. By comparing the measurements to calculations an isomeric dependence of the resonant spectra is found giving preference to two of the four possible isomers in the polymer.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-54985 (URN)10.1016/S0368-2048(98)00354-5 (DOI)
    Available from: 2010-04-26 Created: 2010-04-26 Last updated: 2013-10-02
    16. Coherent and incoherent processes in resonant photoemission
    Open this publication in new window or tab >>Coherent and incoherent processes in resonant photoemission
    Show others...
    1997 (English)In: Applied Physics A: Materials Science & Processing, ISSN 0947-8396, E-ISSN 1432-0630, Vol. 65, no 2, 159-167 p.Article in journal (Refereed) Published
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-54989 (URN)10.1007/s003390050559 (DOI)
    Available from: 2010-04-26 Created: 2010-04-26 Last updated: 2014-11-13Bibliographically approved
    17. Electronic structure of buried Si layers in GaAs(001) as studied by soft-x-ray emission
    Open this publication in new window or tab >>Electronic structure of buried Si layers in GaAs(001) as studied by soft-x-ray emission
    Show others...
    1995 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, Vol. 52, R8643-R8645 p.Article in journal (Refereed) Published
    Abstract [en]

    It is demonstrated that it is possible to investigate details of the electronic structure of an internal atomic monolayer using soft-x-ray-emission spectroscopy. The local and partial density of states of one monolayer and three monolayers of Si, embedded deep below a GaAs(001) surface, was extracted. Clear differences to the density of states for bulk Si were observed.

    National Category
    Natural Sciences Biological Sciences
    Identifiers
    urn:nbn:se:liu:diva-17476 (URN)10.1103/PhysRevB.52.R8643 (DOI)
    Note
    Original Publication:P. O. Nilsson, J. Kanski, J. V. Thordson, T. G. Andersson, J. Nordgren, J. Guo and Martin Magnuson, Electronic structure of buried Si layers in GaAs(001) as studied by soft-x-ray emission, 1995, Physical Review B. Condensed Matter and Materials Physics, (52), R8643-R8645.http://dx.doi.org/10.1103/PhysRevB.52.R8643Copyright: American Physical Societyhttp://www.aps.org/Available from: 2009-03-26 Created: 2009-03-25 Last updated: 2013-10-02Bibliographically approved
    18. Resonant Photoemission at the 2p Edges of Ni: Resonant Raman and Interference Effects
    Open this publication in new window or tab >>Resonant Photoemission at the 2p Edges of Ni: Resonant Raman and Interference Effects
    Show others...
    1997 (English)In: Physical Review Letters, ISSN 0031-9007, Vol. 78, no 5, 967-970 p.Article in journal (Refereed) Published
    Abstract [en]

    Unambiguous evidence for resonant photoemission in Ni is presented. Interference effects are identified at the 2p edges for the valence band and the 6 eV satellite. A rapid transition from a resonant Raman to an Auger-like regime shows that the core-excited states above threshold are not localized enough to significantly enhance the photoemission intensity, implying a large fraction of incoherent intensity. The results indicate that the appearance of interference effects does not require strong localization of the intermediate state.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-17473 (URN)10.1103/PhysRevLett.78.967 (DOI)
    Note
    Original Publication:M. Weinelt, A. Nilsson, Martin Magnuson, T. Wiell, N. Wassdahl, O. Karis, A. Föhlisch, N. Mårtensson, J. Stöhr and M. Samant, Resonant Photoemission at the 2p Edges of Ni: Resonant Raman and Interference Effects, 1997, Physical Review Letters, (78), 5, 967-970.http://dx.doi.org/10.1103/PhysRevLett.78.967Copyright: American Physical Societyhttp://www.aps.org/Available from: 2009-03-26 Created: 2009-03-25 Last updated: 2013-10-02Bibliographically approved
  • 26.
    Magnuson, Martin
    Uppsala University.
    Engagerad Fysiker Fyller Fyrtio År2005Report (Other (popular science, discussion, etc.))
  • 27.
    Magnuson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Induced magnetism at the interfaces of a Fe/V superlattice investigated by resonant magnetic x-ray scattering2017In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 422, 362-366 p.Article in journal (Refereed)
    Abstract [en]

    The induced magnetic moments in the V 3d electronic states of interface atomic layers in a Fe(6ML)/V(7ML) superlattice was investigated by x-ray resonant magnetic scattering. The first V atomic layer next to Fe was found to be strongly antiferromagnetically polarized relatively to Fe and the magnetic moments of the next few atomic layers in the interior V region decay exponentially with increasing distance from the interface, while the magnetic moments of the Fe atomic layers largely remain bulk-like. The induced V moments decay more rapidly as observed by x-ray magnetic scattering than in standard x-ray magnetic circular dichroism. The theoretical description of the induced magnetic atomic layer profile in V was found to strongly rely on the interface roughness within the superlattice period. These results provide new insight into interface magnetism by taking advantage of the enhanced depth sensitivity to the magnetic profile over a certain resonant energy bandwidth in the vicinity of the Bragg angles.

    The full text will be freely available from 2018-09-03 11:32
  • 28.
    Magnuson, Martin
    Uppsala University.
    Investigation of Ti2AlC and TiC by soft x-ray emission spectroscopy2007In: Journal of Physics: Conference Series 61 / [ed] Ernst Meyer, Martin Hegner, Christoph Gerber and Hans-Joachim Güntherodt, 2007, 760-764 p.Conference paper (Refereed)
    Abstract [en]

    The electronic structure of the MAX-phase Ti pectroscopy. This nanolaminated carbide compound represents a class of layered materials with a combination of properties from both metals and ceramics. The bulk-sensitive soft x-ray emission technique is shown to be particularly useful for detecting detailed electronic structure information about internal monolayers and interfaces. The Ti-Al bonding is manifested by a pronounced peak in the Ti present in the binary TiC system. The spectral shape of Al in comparison to metallic Al. By replacing the constituting elements, a change of the electron population can be achieved causing a change of covalent bonding between the laminated layers, which enables control of the macroscopic properties of the material. 

  • 29.
    Magnuson, Martin
    Department of Physics, Uppsala University.
    Max-Phases Investigated by Soft X-Ray Emission Spectroscopy2006In: Mechanical Properties and Performance of Engineering Ceramics II: Ceramic Engineering and Science Proceedings, Volume 7, Issue 2 / [ed] Rajan Tandon, Andrew Wereszczak, Edgar Lara-Curzio, 2006, 325-329 p.Conference paper (Refereed)
    Abstract [en]

    The electronic structures of the MAX-phases Ti3AlC2, Ti3SiC2 and Ti3GeC2 were investigated by soft X-ray emission spectroscopy. These nanolaminated carbide compounds represent a class of layered materials with a combination of properties from both metals and ceramics. The bulk-sensitive soft X-ray emission technique is shown to be particularly useful for detecting detailed electronic structure information about internal monolayers and interfaces. A weak covalent Ti-Al bond is manifested by a pronounced shoulder in the Ti L-emission of Ti3AlC2. When Al is replaced by Si or Ge, the shoulder disappears. Furthermore, the spectral shapes of Al, Si and Ge in the MAX-phases are strongly modified in comparison to the corresponding pure elements. By varying the constituting elements, a change of the electron population is achieved causing a change of covalent bonding between the laminated layers, which enables control of the macroscopic properties of the material.

  • 30.
    Magnuson, Martin
    Uppsala University.
    Mjukröntgen i Nanovärlden2005Report (Other (popular science, discussion, etc.))
  • 31.
    Magnuson, Martin
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Process Control Methods for Operation of Superconducting Cavities at the LEP Accelerator at CERN1992Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this thesis is to analyse the cryogenic process for cooling superconducting radio frequency accelerator test cavities in the LEP accelerator at CERN. A liquefaction cryoplant is analysed, including the production of liquid helium at 4.5 K, the systems for distribution and regulation of liquid helium, and the radio frequency field used for accelerating particles. After discussing regulation problems and modifications planned for a new cavity installation in 1992, different techniques for specifying the control programs for the new installation are evaluated. Various diagramming techniques, standards and methodologies, and Computer Aided Software Engineering-tools, are compared as to their practical usefulness in this kind of process control. Finally, in accordance with anticipated requirements, possible ways of making high and low level control program specifications are suggested.

  • 32.
    Magnuson, Martin
    CERN, Genva, Switzerland.
    Process Control Methods for Operation of Superconducting Cavities at the LEP Accelerator at CERN1992Report (Other academic)
    Abstract [en]

    The aim of this work is to analyse the cryogenic process for cooling superconducting radio-frequency accelerator prototype cavities in the Large Electron-Positron collider (LEP) at CERN. A liquefaction cryoplant is analysed, including the production of liquid helium at 4.5 K, the systems for distribution and control of liquid helium, and the radio-frequency system used for accelerating particles. The cryogenic control problems of the cavities based on operation experiences of the prototype modules in 1991 and different solutions and modifications for the future cavity installations are presented in detail. In addition, different techniques for specifying the control programs for new cavities are evaluated. Various diagramming techniques, standards and methodologies, and ComputerAided Software Engineering (CASE) tools, are compared regarding their practical usefulness for the cryogenic process control.

  • 33.
    Magnuson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Q-dependent RIXS investigation of low-energy excitations in single-crystal mixed valence manganese perovskites2009Report (Other academic)
  • 34.
    Magnuson, Martin
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    RIXS Investigation of Zhang-Rice Excitations in single-crystal YBa2Cu3O7-x2008Report (Other academic)
  • 35.
    Magnuson, Martin
    Uppsala University.
    Study of Cryogenic Losses in a Liquid Helium Transfer Line1992Report (Other academic)
    Abstract [en]

    The cryogenic losses in a 30° bend of a transfer line manufactured by the company l'Air Liquide for the helium supply to superconducting cavities at interaction point 2 in the Large Electron Positron Collider (LEP) were studied as function of the surface temperature distribution. The possibility of using an infrared (IR) temperature-measurement system to estimate the losses was evaluated. Two different coatings of paint on the pipe were tested in a laboratory environment in order to minimize reflection of thermal radiation from the pipe surface. Colour images were recorded from an operating transfer-line bend in a LEP service tunnel. Heat transfer calculations of the losses from the bend surface were made and compared with calculations of internal conduction.

  • 36.
    Magnuson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Surface Plasmon Resonance in Thin Gold Films1993Report (Other academic)
    Abstract [en]

    Surface plasmon resonance (SPR) is an optical technique that can be used for biosensing. The present work accounts for calculations and experiments with different glass prisms in both air and water. The possibility of making useful sensing probes combined with optical fibres is discussed.

  • 37.
    Magnuson, Martin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Andersson, Matilda
    Uppsala University.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jansson, Ulf
    Uppsala University.
    Electronic Structure and Chemical Bonding of AmorphousChromium Carbide Thin Films2012In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 24, 225004- p.Article in journal (Refereed)
    Abstract [en]

    The microstructure, electronic structure, and chemical bonding of chromium carbidethin films with different carbon contents have been investigated with high-resolutiontransmission electron microscopy, electron energy loss spectroscopy and soft x-rayabsorption-emission spectroscopies. Most of the films can be described as amorphousnanocomposites with non-crystalline CrCx in an amorphous carbon matrix. At highcarbon contents, graphene-like structures are formed in the amorphous carbon matrix.At 47 at% carbon content, randomly oriented nanocrystallites are formed creating acomplex microstructure of three components. The soft x-ray absorption-emissionstudy shows additional peak structures exhibiting non-octahedral coordination andbonding.

  • 38.
    Magnuson, Martin
    et al.
    Uppsala University.
    Butorin, S. M.
    Uppsala University.
    Guo, J.-H.
    Uppsala University.
    Agui, A.
    Uppsala University.
    Nordgren, J.
    Uppsala University.
    Ogasawara, H.
    University of Tokyo.
    Kotani, A.
    University of Tokyo.
    Takahashi, T.
    Tohoku University.
    Kunii, S.
    Tohoku University.
    Electronic-structure investigation of CeB6 by means of soft-x-ray scattering2001In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 63, no 075101Article in journal (Refereed)
    Abstract [en]

    The electronic structure of the heavy fermion compound CeB6 is probed by resonant inelastic soft-x-ray scattering using photon energies across the Ce 3d and 4d absorption edges. The hybridization between the localized 4f orbitals and the delocalized valence-band states is studied by identifying the different spectral contributions from inelastic Raman scattering and normal fluorescence. Pronounced energy-loss structures are observed below the elastic peak at both the 3d and 4d thresholds. The origin and character of the inelastic scattering structures are discussed in terms of charge-transfer excitations in connection to the dipole allowed transitions with 4f character. Calculations within the single-impurity Anderson model with full multiplet effects are found to yield consistent spectral functions to the experimental data.

  • 39.
    Magnuson, Martin
    et al.
    Uppsala University.
    Butorin, S. M.
    Uppsala University.
    Guo, J.-H.
    Uppsala University.
    Nordgren, J.
    Uppsala University.
    Electronic structure investigation of CoO by means of soft x-ray scattering2002In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 65, no 205106Article in journal (Refereed)
    Abstract [en]

    The electronic structure of CoO is studied by resonant inelastic soft x-ray scattering spectroscopy using photon energies across the Co 2p absorption edges. The different energy-loss structures in the Raman scattering spectra are identified as due to d-d and charge-transfer excitations. For excitation energies close to the L3 resonance, the spectral features are dominated by quartet-quartet and quartet-doublet transitions of the 3d7 configuration. At excitation energies corresponding to the satellites in the Co 2p x-ray-absorption spectrum of CoO, the emission features are instead dominated by charge-transfer transitions to the 3d8-1 final state. The spectra are interpreted and discussed with the support of simulations within the single-impurity Anderson model with full multiplet effects which are found to yield consistent spectral functions to the experimental data.

  • 40.
    Magnuson, Martin
    et al.
    Uppsala University.
    Butorin, S. M.
    Uppsala University.
    Såthe, C.
    Uppsala University.
    Nordgren, J.
    Uppsala University.
    Ravindran, P.
    University of Oslo.
    Spin transition in LaCoO3 investigated by resonant soft X-ray emission spectroscopy2004In: Europhysics letters, ISSN 0295-5075, E-ISSN 1286-4854, Vol. 68, no 2, 289-295 p.Article in journal (Refereed)
    Abstract [en]

    The spin transition in LaCoO3 is investigated by temperature-dependent resonant soft X-ray emission spectroscopy near the Co 2p absorption edges. This element-specific technique is more bulk sensitive with respect to the temperature-induced spin state of the Co3+ ions in LaCoO3 than other high-energy spectroscopic methods. The spin transition is interpreted and discussed with ab initio density-functional theory within the fixed-spin moment method, which is found to yield consistent spectral functions to the experimental data. The spectral changes for LaCoO3 as a function of temperature suggest a change in spin state as the temperature is raised from 85 to 300 K, while the system remains in the same spin state as the temperature is further increased to 510 K.

  • 41.
    Magnuson, Martin
    et al.
    Uppsala University.
    Butorin, Sergei
    Uppsala University.
    Agui, Akane
    Uppsala University.
    Nordgren, Joseph
    Uppsala University.
    Resonant soft x-ray Raman scattering of NiO2002In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 14, no 13, 3669-3676 p.Article in journal (Refereed)
    Abstract [en]

    Resonant soft x-ray Raman scattering measurements on NiO have been made at photon energies across the Ni 2p absorption edges. The details of the spectral features are identified as Raman scattering due to d-d and charge-transfer excitations. The spectra are interpreted within the single-impurity Anderson model, including multiplets, crystal-field and charge-transfer effects. At threshold excitation, the spectral features consists of triplet-triplet and triplet-singlet transitions of the 3d8 configuration. For excitation energies corresponding to the charge-transfer region in the Ni 2p x-ray absorption spectrum of NiO, the emission spectra are instead dominated by charge-transfer transitions to the 3d9\underline L-1 final state. Comparisons of the final states with other spectroscopical techniques are also made.

  • 42.
    Magnuson, Martin
    et al.
    Uppsala University.
    Butorin, Sergei M.
    Uppsala University.
    Werme, Lars
    Uppsala University.
    Nordgren, Joseph
    Uppsala University.
    Ivanov, Kirill E.
    RRC Kurchatov Institute, Moscow.
    Guo, Jinghua
    Lawrence Berkeley National Laboratory, Berkeley, USA.
    Shuh, David K.
    Lawrence Berkeley National Laboratory, Berkeley, USA.
    Uranium oxides investigated by X-ray absorption and emission spectroscopies2006In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 252, no 115, 5615-6518 p.Article in journal (Refereed)
    Abstract [en]

    X-ray absorption and resonant X-ray emission measurements at the O 1s edge of the uranium oxides UO2, U3O8 and UO3 are presented. The spectral shapes of the O Kα X-ray emission spectra of UO3 exhibit significant excitation energy dependence, from an asymmetric to a symmetric form, which differs from those of UO2 and U3O8. This energy dependence is attributed to a significant difference in the oxygen–uranium hybridization between two different sites in the crystal structure of UO3. The spectral shapes of UO2 and U3O8 are also found to be different but without significant energy dependence. The experimental spectra of the valence and conduction bands of the uranium oxides are compared to the results of electronic structure calculations available in the literature.

  • 43.
    Magnuson, Martin
    et al.
    Uppsala University.
    Duda, L.-C.
    Uppsala University.
    Butorin, S. M.
    Uppsala University.
    Kuiper, P.
    Växjö University.
    Nordgren, J.
    Uppsala University.
    Large magnetic circular dichroism in resonant inelastic x-ray scattering at the Mn L-edge of Mn-Zn ferrite2006In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 74, no 172409Article in journal (Refereed)
    Abstract [en]

    Wereport resonant inelastic x-ray scattering (RIXS) excited by circularly polarizedx rays on Mn-Zn ferrite at the Mn L2,3 resonances.We demonstrate that crystal-field excitations, as expected for localized systems,dominate the RIXS spectra and thus their dichroic asymmetry cannotbe interpreted in terms of spin-resolved partial density of states,which has been the standard approach for RIXS dichroism. Weobserve large dichroic RIXS at the L2 resonance which weattribute to the absence of metallic core hole screening inthe insulating Mn ferrite. On the other hand, reduced L3-RIXSdichroism is interpreted as an effect of longer scattering timethat enables spin-lattice core hole relaxation via magnons and phononsoccurring on a femtosecond time scale.

  • 44.
    Magnuson, Martin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Uhrberg, Roger
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics.
    Johansson, Leif
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Total of 100 authors in alphabetical orders, -
    MAX IV Conceptual Design Report (CDR)2006Report (Other academic)
  • 45.
    Magnuson, Martin
    et al.
    Uppsala University.
    Guo, J.
    Uppsala University.
    Såthe, C.
    Uppsala University.
    Rubensson, J.-E.
    Uppsala University.
    Nordgren, J.
    Uppsala University.
    Glans, P.
    Stockholm University.
    Yang, L.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Sałek, P.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Ågren, H.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Competition between decay and dissociation of core-excited carbonyl sulfide studied by x-ray scattering1999In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 59, 4281-4287 p.Article in journal (Refereed)
    Abstract [en]

    We show evidence of dissociation during resonant inelastic soft x-ray scattering. Carbon and oxygen K-shell and sulfur L-shell resonant and nonresonant x-ray emission spectra were measured using monochromatic synchrotron radiation for excitation and ionization. After sulfur L2,3→π*, σ* excitation, atomic lines are observed in the emission spectra as a consequence of competition between de-excitation and dissociation. In contrast the carbon and oxygen spectra show weaker line-shape variations and no atomic lines. The spectra are compared to results from ab initio calculations. The discussion of the dissociation paths is based on calculated potential energy surfaces and atomic transition energies.

  • 46.
    Magnuson, Martin
    et al.
    Uppsala University.
    Guo, J.-H.
    Uppsala University.
    Butorin, S.-M.
    Uppsala University.
    Agui, A.
    Uppsala University.
    Såthe, C.
    Uppsala University.
    Nordgren, J.
    Uppsala University.
    Monkman, A.
    University of Durham.
    The electronic structure of polyaniline and doped phases studied by soft X-ray absorption and emission spectroscopies1999In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 111, no 10, 4756-4761 p.Article in journal (Refereed)
    Abstract [en]

    The electronic structure of the conjugated polymer, polyaniline, has been studied by resonant and nonresonant soft x-ray emission spectroscopy using synchrotron radiation for the excitation. The measurements were made on polyaniline and a few doped (protonated) phases for both the carbon and nitrogen contents. The resonant x-ray emission spectra show depletion of the π electron bands due to the selective excitation which enhances the effect of symmetry selection rules. The valence band structures in the x-ray emission spectra attributed to the π bands show unambiguous changes of the electronic structure upon protonation. By comparing to x-ray absorption measurements, the chemical bonding and electronic configuration is characterized.

  • 47.
    Magnuson, Martin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Guo, J.-H.
    Såthe, C.
    Agui, A.
    Nordgren, J.
    Resonant and nonresonant X-ray emission spectroscopy of poly(pyridine-2,5-diyl)1998Report (Other (popular science, discussion, etc.))
  • 48.
    Magnuson, Martin
    et al.
    Department of Physics, Uppsala University, Uppsala, Sweden.
    Guo, Jinghua
    Department of Physics, Uppsala University, Uppsala, Sweden.
    Såthe, Conny
    Department of Physics, Uppsala University, Uppsala, Sweden.
    Agui, Akane
    Department of Physics, Uppsala University, Uppsala, Sweden.
    Nordgren, Joseph
    Department of Physics, Uppsala University, Uppsala, Sweden.
    Resonant and nonresonant x-ray emission spectroscopy of poly(pyridine-2,5-diyl)1998In: Advance Light Source: Compendium of User Abstracts and Technical Reports / [ed] Deborah J. Dixon, Arthur L. Robinson, Annette Greiner, and Constance Silva, Berkeley: University of California , 1998, , 4 p.135-138 p.Chapter in book (Other academic)
    Abstract [en]

    Conjugated polymers have been the subject of much interest owing to their unique electronic properties which can be technically exploited e.g., as doping induced electrical conductors and light emitting diodes [ I]. Detailed experimental studies of the uppermost 7t-orbital levels at the valence band edges of these polymers are important to gain an understanding of their properties. Such studies have been carried out by many techniques including photoelectron spectroscopy using photon excitation in both the x-ray and ultraviolet wavelength regimes....

  • 49.
    Magnuson, Martin
    et al.
    Université Pierre et Marie Curie, Paris.
    Hague, Coryn
    Université Pierre et Marie Curie, Paris.
    Determination of the refractive index at soft X-ray resonances2004In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, Vol. 137, 519-522 p.Article in journal (Refereed)
    Abstract [en]

    The dispersive part of the refractive index, 1−δ, of vanadium is determined by measuring the angular dependence of the Bragg peak at the V L2,3 edge energy region using a Fe/V superlattice. This X-ray scattering technique provides access to the direct determination of the dispersive part of the refractive index across an absorption resonance and to the change of values from below unity to above unity. We demonstrate that previously tabulated values tend to underestimate the amplitude of the change in the real part of the refractive index. We also examine the need for applying absorption and polarization corrections.

  • 50.
    Magnuson, Martin
    et al.
    Uppsala University.
    Karis, O.
    Uppsala University.
    Weinelt, M.
    Uppsala University.
    Wassdahl, N.
    Uppsala University.
    Nilsson, A.
    Uppsala University.
    Mårtensson, N.
    Stöhr, J.
    Uppsala University.
    Samant, M.
    Almaden Research Center, San Jose.
    Coherent and incoherent processes in resonant photoemission1997Report (Other academic)
12 1 - 50 of 85
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