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  • 1.
    Alfredsson, Y.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Rensmo, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Sandell, A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Siegbahn, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Electronic structure of TiOPc thin film on conducting glass studied by means of X-ray and photoelectron spectroscopies2009In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, E-ISSN 1873-2526, Vol. 174, no 1-3, p. 50-54Article in journal (Refereed)
    Abstract [en]

    Thin films of TiOPc have been investigated using photoelectron   spectroscopy (PES) and X-ray spectroscopy (XAS). The results are   interpreted in terms of the local geometry around the metal center both   with regard to bonding and crystal field symmetry. Core and valence PES   have been found to be in accordance with the structural characteristics   of the TiOPc molecule. For resonant PES at the N1s and Ti2p edges,   information on the local electronic structure of the occupied molecular   orbitals has been obtained. Ti2p XAS was interpreted in terms of   five-fold coordination around the titanium atom for TiOPc of C-4V   symmetry. Angle-resolved N1s XAS suggests the molecular planes to order   preferentially parallel to the sample surface plane.

  • 2. Aziz, Emad F
    et al.
    Gråsjö, Johan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Forsberg, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Andersson, Egil
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Söderström, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Duda, Laurent
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Zhang, Wenhua
    Yang, Jinglong
    Eisebitt, Stefan
    Bergström, Christel
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Luo, Yi
    Nordgren, Joseph
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Eberhardt, Wolfgang
    Rubensson, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Photoinduced Formation of N2 Molecules in Ammonium Compounds2007In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 111, no 39, p. 9662-9669Article in journal (Refereed)
    Abstract [en]

    Via fluorescence yield (FY) and resonant inelastic scattering spectroscopy in the soft X-ray range we find that soft X-rays induce formation of N2 molecules in solid NH4Cl and in related compounds. The nitrogen molecules form weak bonds in NH4Cl, so that a substantial fraction of the molecules remains in the sample. From measurements of the FY as a function of exposure and temperature, the rates for the photochemical processes are estimated. At elevated temperatures (363 K), several nitrogen atoms are removed from the sample per incoming photon. At lower temperatures (233 K), the rate is reduced to around 0.02 nitrogen atoms for each incoming photon. Virtually all these atoms form N2 molecules which are bound in the sample. The generality and implications of these results are briefly discussed.

  • 3.
    Bao, Z
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Fink, R. F
    Travnikova, O
    Céolin, D
    Hjelte, I
    Kivimäki, A
    Piancastelli, M. N
    The PCI Effect in the O2 Near ThresholdMolecular Normal Auger SpectraManuscript (Other academic)
  • 4.
    Bao, Z
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Travnikova, O
    Céolin, D
    Piancastelli, M. N
    Shape Resonance Affected Molecular Auger Post Collision Interaction (MAPCI) Effect of NO N K-edge Near Threshold Normal Auger SpectraManuscript (Other academic)
  • 5.
    Bao, Zhuo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Synchrotron Radiation Studies of Free and Adsorbed Molecules2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis contains two parts. The first part concerns the research work on free molecules using synchrotron-radiation-related techniques. Auger electron spectra of two free open-shell molecules, O2 and NO, were studied experimentally and theoretically. Photoionization experimental technique with tunable synchrotron radiation source was used to induce core-level electron ionization and obtain the KVV normal Auger electron spectra. A quantitative assignment of O2 normal Auger spectrum was obtained by applying ab initio CI calculations and LVI Auger line shape simulations including the bond length dependence of Auger transition rates. The photon energy dependence of normal Auger electron spectra was focused on with photon energies in the vicinities of core-ionization threshold energies. Consequently, the MAPCI (Molecular Auger Post Collision Interaction) theory was developed. Taking the near-threshold O2 normal Auger spectrum as an example, the two extreme cases of MAPCI effect, “atomic-like PCI” and “molecular PCI”, were discovered and discussed. The effect of shape resonance on near-threshold molecular normal Auger spectrum was discussed taking NO near threshold normal Auger spectra as example.

    The second part deals with research work on the chemisorption of small epoxy organic molecules, ethylene oxide, methyl oxirane, on Si (100) surfaces. Synchrotron radiation related techniques, UPS, XPS and NEXAFS, were applied. Based on the valence photoemission spectra, C 1s and Si 2p XPS spectra, the epoxy ring opening reactions of these molecules in chemisorption process were proved. Further tentative search for the surface-adsorbate CDAD effect was performed, and no evident circular dichroism was confirmed.

    List of papers
    1. Detailed Theoretical and Experimental Description of Normal Auger Decay in O2
    Open this publication in new window or tab >>Detailed Theoretical and Experimental Description of Normal Auger Decay in O2
    Show others...
    2008 (English)In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 41, no 12, p. 125101-Article in journal (Refereed) Published
    Abstract [en]

    The normal Auger electron spectrum of the O-2 molecule is assigned in detail on the basis of ab initio valence configuration interaction (CI) wavefunctions. Potential energy curves of the ground state, the core-ionized states and the doubly charged final states are calculated and Auger decay rates are obtained with the one-centre approximation. Using the lifetime vibrational interference method, band shapes are obtained for all contributions to the Auger spectrum. The calculated Auger electron spectrum allows us to identify all features observed experimentally. Significant differences to previous assignments are reported. A quantitative simulation of the spectrum is given on the basis of a curve-fitting procedure, in which the energetic positions and intensities of the theoretical bands were optimized. Besides providing a basis for a refined analysis of the spectrum, the fit allows us to assess the accuracy of the calculation. As expected for this level of theory, the absolute accuracy of the valence CI energies is found to be about 0.3 eV. The inherent error of the one-centre transition rates is less than 5% of the most intense transition in the spectrum. The frequently questioned one-centre Auger transition rates are shown to be rather appropriate if applied with reasonable wavefunctions and if the vibrational band structure of the molecular spectrum is properly taken into account.

    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-96986 (URN)10.1088/0953-4075/41/12/125101 (DOI)000257177700004 ()
    Available from: 2008-04-03 Created: 2008-04-03 Last updated: 2017-12-14Bibliographically approved
    2. The PCI Effect in the O2 Near ThresholdMolecular Normal Auger Spectra
    Open this publication in new window or tab >>The PCI Effect in the O2 Near ThresholdMolecular Normal Auger Spectra
    Show others...
    Manuscript (Other academic)
    Identifiers
    urn:nbn:se:uu:diva-96987 (URN)
    Available from: 2008-04-03 Created: 2008-04-03 Last updated: 2010-01-13Bibliographically approved
    3. Shape Resonance Affected Molecular Auger Post Collision Interaction (MAPCI) Effect of NO N K-edge Near Threshold Normal Auger Spectra
    Open this publication in new window or tab >>Shape Resonance Affected Molecular Auger Post Collision Interaction (MAPCI) Effect of NO N K-edge Near Threshold Normal Auger Spectra
    Manuscript (Other academic)
    Identifiers
    urn:nbn:se:uu:diva-96988 (URN)
    Available from: 2008-04-03 Created: 2008-04-03 Last updated: 2010-01-13Bibliographically approved
    4. Electronic Structure of Core-excited and Core-ionized Methyl Oxirane
    Open this publication in new window or tab >>Electronic Structure of Core-excited and Core-ionized Methyl Oxirane
    Show others...
    2007 (English)In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, E-ISSN 1873-2526, Vol. 156, p. 259-264Article in journal (Refereed) Published
    Abstract [en]

    We report a detailed analysis of the electronic structure of methyl oxirane, including core-level photoelectron spectroscopy, X-ray absorption at both C and O K-shells, resonant Auger and normal Auger spectroscopy. The X-ray absorption spectra (XAS) around the C K-edge can be easily interpreted on the ground of the chemical shift between the carbon atoms with different chemical environments. The X-ray absorption data around the O K-edge are quite structureless, hinting for a likely fragmentation process (possibly implying a ring-opening reaction).

    In resonant Auger spectra obtained after excitation below both the C 1s and O 1s ionization thresholds we notice a predominance of spectator decay implying a strong mixing between empty molecular orbitals and Rydberg states.

    Keywords
    Auger decay, X-ray, Fragmentation, Chiral
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-96989 (URN)10.1016/j.elspec.2006.12.068 (DOI)000246726300305 ()
    Available from: 2008-04-03 Created: 2008-04-03 Last updated: 2017-12-14Bibliographically approved
    5. Electronic and Geometric Structure of Methyl Oxirane Adsorbed on Si (100) 2 × 1
    Open this publication in new window or tab >>Electronic and Geometric Structure of Methyl Oxirane Adsorbed on Si (100) 2 × 1
    Show others...
    2007 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 254, no 1, p. 108-112Article in journal (Refereed) Published
    Abstract [en]

    Electronic and geometric properties of the adsorbate–substrate complex formed upon adsorption of methyl oxirane on Si(1 0 0)2 × 1 at room temperature is reported, obtained with synchrotron radiation-induced valence and core-level photoemission. A ring-opening reaction is demonstrated to occur, followed by a five-membered ring formation involving two of the Si surface atoms bound to a surface dimer. Core-level photoemission spectra support the ring-opening reaction and the SiO and SiC bond formation, while from the valence spectra a more extended molecular fragmentation can be ruled out. We discuss the most likely geometry of the five-membered ring.

    Keywords
    Adsorption, Electronic structure, Geometrical structure, Semiconductors
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-96990 (URN)10.1016/j.apsusc.2007.07.070 (DOI)000250800100025 ()
    Available from: 2008-04-03 Created: 2008-04-03 Last updated: 2017-12-14
    6. The Bonding of Chemisorbed Ethylene Oxide on Si (100) Surface
    Open this publication in new window or tab >>The Bonding of Chemisorbed Ethylene Oxide on Si (100) Surface
    Manuscript (Other academic)
    Identifiers
    urn:nbn:se:uu:diva-96991 (URN)
    Available from: 2008-04-03 Created: 2008-04-03 Last updated: 2011-12-02
    7. Search for Circular Dichroism Effects in Methyl Oxirane Adsorbed on Si (100)
    Open this publication in new window or tab >>Search for Circular Dichroism Effects in Methyl Oxirane Adsorbed on Si (100)
    Show others...
    (English)Article in journal (Refereed) Submitted
    Identifiers
    urn:nbn:se:uu:diva-96992 (URN)
    Available from: 2008-04-03 Created: 2008-04-03 Last updated: 2011-02-17Bibliographically approved
  • 6.
    Bao, Zhuo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Fink, Reinhold F.
    Travnikova, Oksana
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Céolin, Denis
    Svensson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Piancastelli, Maria Novella
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Detailed Theoretical and Experimental Description of Normal Auger Decay in O22008In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 41, no 12, p. 125101-Article in journal (Refereed)
    Abstract [en]

    The normal Auger electron spectrum of the O-2 molecule is assigned in detail on the basis of ab initio valence configuration interaction (CI) wavefunctions. Potential energy curves of the ground state, the core-ionized states and the doubly charged final states are calculated and Auger decay rates are obtained with the one-centre approximation. Using the lifetime vibrational interference method, band shapes are obtained for all contributions to the Auger spectrum. The calculated Auger electron spectrum allows us to identify all features observed experimentally. Significant differences to previous assignments are reported. A quantitative simulation of the spectrum is given on the basis of a curve-fitting procedure, in which the energetic positions and intensities of the theoretical bands were optimized. Besides providing a basis for a refined analysis of the spectrum, the fit allows us to assess the accuracy of the calculation. As expected for this level of theory, the absolute accuracy of the valence CI energies is found to be about 0.3 eV. The inherent error of the one-centre transition rates is less than 5% of the most intense transition in the spectrum. The frequently questioned one-centre Auger transition rates are shown to be rather appropriate if applied with reasonable wavefunctions and if the vibrational band structure of the molecular spectrum is properly taken into account.

  • 7.
    Björneholm, Olle
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Ohrwall, Gunnar
    Tchaplyguine, Maxim
    Free clusters studied by core-level spectroscopies2009In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 601, no 1-2, p. 161-181Article, review/survey (Refereed)
    Abstract [en]

    In this review we describe the development and current status of free clusters studied using core-level spectroscopies. This topic ranges from simple model systems, such as rare gas clusters, to molecular clusters, and clusters of solids, held together by ionic, covalent and metallic bonding.

  • 8. Blomquist, J.
    et al.
    Walle, L. E.
    Uvdal, P.
    Borg, A.
    Sandell, A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Water Dissociation on Single Crystalline Anatase TiO2(001) Studied by Photoelectron Spectroscopy2008In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 112, no 42, p. 16616-16621Article in journal (Refereed)
    Abstract [en]

    The adsorption of water on the anatase TiO2(001)-(4 x 1) surface is studied using synchrotron radiation-excited core level photoelectron spectroscopy. The coverage-dependent adsorption of water at low temperature is monitored and compared to the sequence obtained after heating of a water multilayer. Two adsorption phases of submonolayer coverage can be defined: Phase 1 consists only of dissociated water, observed as OH-groups. This phase is found at low coverage at low temperature (190 K) and is the only state of adsorbed water above similar to 230 K. The saturation coverage of phase 1 is consistent with dissociation on the 4-fold-coordinated Ti ridge atoms of the (4 x 1) surface reconstruction. Phase 2 is found at higher coverage, reached at lower temperature. It consists of a mixture of dissociated and molecular water with a ratio of 1:1 at 170 K. The molecular water is found to bond to the hydroxyl groups. The hydroxyl coverage of phase 2 is approximately 2 times that of phase 1. The results suggest that the OH and H2O species of phase 2 are confined to the ridges of the surface.

  • 9. Bonhommeau, S.
    et al.
    Ottosson, Niklas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Pokapanich, Wandared
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Svensson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Eberhardt, W.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Aziz, E.
    Solvent Effect of Alcohols at the L-edge of Iron in Solution: X-ray Absorption and Multiplet Calculations2008In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 112, no 40, p. 12571-12574Article in journal (Refereed)
  • 10. Cavar, E.
    et al.
    Westerström, R.
    Mikkelsen, A.
    Lundgren, E.
    Vinogradov, A. S.
    Ng, May Ling
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Preobrajenski, A. B.
    Zakharov, A. A.
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    A single h-BN layer on Pt(111)2008In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 602, no 9, p. 1722-1726Article in journal (Refereed)
    Abstract [en]

    The structure and formation of an ultrathin hexagonal boron nitride (h-BN) film on Pt(111) has been studied by a combination of scanning tunneling microscopy, low energy electron diffraction, low energy electron microscopy, X-ray absorption and high resolution core level spectroscopy. The study shows that a single boron nitride layer is formed on Pt(111), resulting in a coincidence structure. High resolution scanning tunneling microscopy (STM) images of the h-BN ultrathin film display only one of the atomic species in the unit cell. Probing the boron and nitrogen related local density of states by near edge X-ray absorption fine structure measurements we conclude that the nitrogen sublattice is visible in STM images. The growth of the single hexagonal boron nitride layer by vapourized borazine in the pressure range of 1 x 10(-6)-1 x 10(-8) at 800 degrees C is further studied by low energy electron microscopy, and reveals that the number of nucleation sites and the perfection of the growth is strongly pressure dependent. A model for the single, hexagonal, boron nitride layer on Pt(111) is proposed.

  • 11.
    Céolin, D
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Piancastelli, Maria Novela
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Stolte, W C
    Lindle, D W
    Partial ion yield spectroscopy around the Cl 2p and C 1s ionization thresholds in CF3Cl2009In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 131, no 24, p. 244301-Article in journal (Refereed)
    Abstract [en]

    We present a partial ion yield experiment on freon 13, CF3Cl, excited in the vicinity of the C 1s and Cl 2p ionization thresholds. We have collected a large amount of cationic fragments and a few anionic fragments at both edges. We have observed a strong intensity dependence of Rydberg transitions with ion fragment size for the CFnCl+ and CFn+/F+ (n=0-3) series at both the Cl 2p and C 1s ionization edges. Selectivity in the fragmentation processes involving the C-Cl and C-F bonds are highlighted by the intensities of the C 1s to lowest unoccupied molecular orbital (LUMO) and LUMO+1 transitions measured on the CFnCl+ and CFn+ yields. Equally, by comparison with their cation counterpart, we discuss possible bond-length dependence for the anion formation at the carbon 1s edge.

  • 12.
    Feifel, Raimund
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Soft X-Ray Physics.
    Velkov, Y.
    Carravetta, V.
    Angeli, C.
    Cimiraglia, R.
    Salek, P.
    Gel'mukhanov, F.
    Sorensen, S. L.
    Piancastelli, Maria-Novella
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Fanis., A. De.
    Okada, K.
    Kitajima, M.
    Tanaka, T.
    Tanaka, H.
    Ueda, K.
    X-ray Absorption and Resonant Auger Spectroscopy of O2 in the Vicinity of the O 1s_σ* Resonance: Experiment and Theory2008In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 128, no 6, p. 064304-Article in journal (Refereed)
    Abstract [en]

    We report on an experimental and theoretical investigation of x-ray absorption and resonant Auger electron spectra of gas phase O-2 recorded in the vicinity of the O 1s ->sigma* excitation region. Our investigation shows that core excitation takes place in a region with multiple crossings of potential energy curves of the excited states. We find a complete breakdown of the diabatic picture for this part of the x-ray absorption spectrum, which allows us to assign an hitherto unexplained fine structure in this spectral region. The experimental Auger data reveal an extended vibrational progression, for the outermost singly ionized X (2)Pi(g) final state, which exhibits strong changes in spectral shape within a short range of photon energy detuning (0 eV>Omega>-0.7 eV). To explain the experimental resonant Auger electron spectra, we use a mixed adiabatic/diabatic picture selecting crossing points according to the strength of the electronic coupling. Reasonable agreement is found between experiment and theory even though the nonadiabatic couplings are neglected. The resonant Auger electron scattering, which is essentially due to decay from dissociative core-excited states, is accompanied by strong lifetime-vibrational and intermediate electronic state interferences as well as an interference with the direct photoionization channel. The overall agreement between the experimental Auger spectra and the calculated spectra supports the mixed diabatic/adiabatic picture.

  • 13. Fink, R. F.
    et al.
    Piancastelli, M. N.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Grum-Grzhimailo, A. N.
    Ueda, K.
    Angular distribution of Auger electrons from fixed-in-space and rotating C 1s -> 2 pi photoexcited CO: Theory2009In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 130, no 1, p. 014306-Article in journal (Refereed)
    Abstract [en]

    The one-center approach for molecular Auger decay is applied to predict the angular distribution of Auger electrons from rotating and fixed-in-space molecules. For that purpose, phase shifts between the Auger decay amplitudes have been incorporated in the atomic model. The approach is applied to the resonant Auger decay of the photoexcited C 1s -> 2 pi resonance in carbon monoxide. It is discussed how the symmetry of the final ionic state is related to features in the angular distributions and a parametrization for the molecular frame Auger electron angular distribution is suggested. The angular distribution of Auger electrons after partial orientation of the molecule by the sigma ->pi-excitation process is also calculated and compared to available experimental and theoretical data. The results of the one-center approach are at least of the same quality as the available theoretical data even though the latter stem from a much more sophisticated method. As the one-center approximation can be applied with low computational demand even to extended systems, the present approach opens a way to describe the angular distribution of Auger electrons in a wide variety of applications.

  • 14.
    Fredin, Kristofer
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Johansson, Erik M. J.
    Blom, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics.
    Hedlund, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Plogmaker, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Using a molten organic conducting material to infiltrate a nanoporous semiconductor film and its use in solid-state dye-sensitized solar cells2009In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 159, no 1-2, p. 166-170Article in journal (Other academic)
    Abstract [en]

    We describe a method to fill thin films of nanoporous TiO2 with solid organic hole-conducting materials and demonstrate the procedure specifically for use in the preparation of dye-sensitized solar cells. Cross-sections of the films were investigated by scanning electron microscopy and it was observed that a hot molten organic material fills pores that are 10 mu m below the surface of the film. We characterized the incident photon to current conversion efficiency properties of the solid TiO2/organic dye/organic hole-conductor heterojunctions and the spectra show that the dye is still active after the melting process.

  • 15. Gisselbrecht, A.
    et al.
    Lindgren, A.
    Burmeister, F.
    Tchaplyguine, M.
    Öhrwall, G.
    Lundin, Marcus
    Naves de Brito, A.
    Svensson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Sorensen, S.
    Size dependent fragmentation of argon clusters in the soft x-ray ionization regime2008In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 128, no 4, p. 044317-Article in journal (Refereed)
    Abstract [en]

    Photofragmentation of argon clusters of average size ranging from 10 up to 1000 atoms is studied using soft x-ray radiation below the 2p threshold and multicoincidence mass spectroscopy technique. For small clusters (< N >=10), ionization induces fast fragmentation with neutral emission imparting a large amount of energy. While the primary dissociation takes place on a picosecond time scale, the fragments undergo slow degradation in the spectrometer on a microsecond time scale. For larger clusters (< N >>= 100) we believe that we observe the fragmentation pattern of multiply charged species on a time-scale which lasts a few hundred nanoseconds. The reason for these slower processes is the large number of neutral atoms which act as an efficient cooling bath where the excess energy ("heat") dissipates among all degrees of freedom. Further degradation of the photoionic cluster in spectrometer then takes place on the microsecond time scale, similar to small clusters.

  • 16. Glover, C.J.
    et al.
    Schmitt, T
    Mattesini, M
    Adell, M
    Ilver, L
    Kanski, J
    Kjeldgaard, L
    Agåker, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Soft X-Ray Physics.
    Mårtensson, N
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Ahuja, R
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    Nordgren, J
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Soft X-Ray Physics.
    Rubensson, J.-E.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Soft X-Ray Physics.
    Stationary and dispersive features in resonant inelastic soft X-ray scattering at the Ge 3p resonances2009In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, E-ISSN 1873-2526, Vol. 173, no 2-3, p. 103-107Article in journal (Refereed)
    Abstract [en]

    Resonant inelastic soft X-ray scattering at the 3p resonances in crystalline Ge is presented. Both stationary and dispersive features are observed in a wide energy range above as well as below the ionization limits. These observations are in agreement with theoretical predictions based on a two-step model where the initially excited electron has no influence on the emission step. Excess population of states in the conduction band is found, and discussed in terms of attosecond electron dynamics. (c) 2009 Elsevier B.V. All rights reserved.

  • 17.
    Granroth, Sari
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    Knut, Ronny
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    Marcellini, Moreno
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    Andersson, Gabriella
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Materials Physics.
    Svensson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Karis, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    Gorgoi, Mihaela
    Schäfers, Franz
    Braun, Walter
    Eberhardt, Wolfgang
    Olovsson, Weine
    Holmström, Erik
    Mårtensson, Nils
    Investigation of interface properties of Ni/Cu multilayers by high kinetic energy photoelectron spectroscopy2009In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 80, no 9, article id 094104Article in journal (Refereed)
    Abstract [en]

    High kinetic-energy photoelectron spectroscopy (HIKE) or hard x-ray   photoelectron spectroscopy has been used to investigate the alloying of   Ni/Cu (100) multilayers. Relative intensities of the corelevels and   their chemical shifts derived from binding energy changes are shown to   give precise information on physicochemical properties and quality of   the buried layers. Interface roughening, including kinetic properties   such as the rate of alloying, and temperature effects on the processes   can be analyzed quantitatively. Using HIKE, we have been able to   precisely follow the deterioration of the multilayer structure at the   atomic scale and observe the diffusion of the capping layer into the   multilayer structure which in turn is found to lead to a segregation in   the ternary system. This is of great importance for future research on   multilayered systems of this kind. Our experimental data are   supplemented by first-principles theoretical calculations of the   core-level shifts for a ternary alloy to allow for modeling of the   influence of capping materials on the chemical shifts.

  • 18.
    Gråsjö, Johan
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Andersson, Egil
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Soft X-Ray Physics.
    Forsberg, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Soft X-Ray Physics.
    Duda, Laurent
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Soft X-Ray Physics.
    Henke, Ev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Pokapanich, Wandared
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Andersson, Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Soft X-Ray Physics.
    Pietsch, Annette
    Hennies, Franz
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Soft X-Ray Physics.
    Jan-Erik, Rubensson
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Soft X-Ray Physics.
    Local Electronic Structure of Functional Groups in Glycine As Anion, Zwitterion, and Cation in Aqueous Solution2009In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 113, no 49, p. 16002-16006Article in journal (Refereed)
    Abstract [en]

    Nitrogen and oxygen K emission spectra of glycine in the form of  anions, zwitterions, and cations in aqueous solution are presented. It  is shown that protonation has a dramatic influence on the local   electronic structure and that the functional groups give a distinct  spectral fingerprint.

     

  • 19.
    Hahlin, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Johansson, Erik M J
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Plogmaker, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Odelius, Michael
    Hagberg, P
    Sun, Licheng
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Electronic and molecular structures of organic dye/TiO2 interfaces for solar cell applications: a core level photoelectron spectroscopy study2010In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 12, no 7, p. 1507-1517Article in journal (Refereed)
    Abstract [en]

    The electronic and molecular properties of three organic dye molecules with the general structure donor-linker-anchor have been investigated using core level photoelectron spectroscopy (PES). The molecules contain a diphenylaniline donor unit, a thiophene linker unit, and cyanoacrylic acid or rhodanine-3-acetic acid anchor units. They have been investigated both in the form of a multilayer and adsorbed onto nanoporous TiO2 and the experimental results were also compared with DFT calculations. The changes at the dye-sensitized TiO2 surface due to the modification of either the donor unit or the anchor unit was investigated and the results showed important differences in coverage as well as in electronic and molecular surface properties. By measuring the core level binding energies, the sub-molecular properties were characterized and the result showed that the adsorption to the TiO2 influences the energy levels of the sub-molecular units differently.

  • 20. Hennies, F
    et al.
    Bao, Z
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Travnikova, O
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Piancastelli, M. N.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Structure and Bonding of Ethylene Oxide on Si(100)2009In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 113, no 36, p. 16077-16082Article in journal (Refereed)
    Abstract [en]

    The bonding configuration and electronic structure of ethylene oxide adsorbed on Si(100)-(2 x 1) is investigated with fully polarization resolved X-ray absorption spectroscopy as well as with core level and valence band photoemission spectroscopy. Ethylene oxide is found to adsorb via a ring-opening reaction, where the molecule forms a five-membered ring together with the silicon surface dimer atoms inserting between a carbon and the oxygen atom. In the resulting geometry, the molecule is tilted out of the surface plane.

  • 21. Hennies, F
    et al.
    Bao, Z
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Travnikova, O
    Piancastelli, M. N
    The Bonding of Chemisorbed Ethylene Oxide on Si (100) SurfaceManuscript (Other academic)
  • 22. Hergenhahn, Uwe
    et al.
    Barth, Silko
    Ulrich, Volker
    Mucke, Melanie
    Joshi, Sanjeev
    Lischke, Toralf
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Rander, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Öhrwall, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    3p valence photoelectron spectrum of Ar clusters2009In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 79, no 15, p. 155448-Article in journal (Refereed)
    Abstract [en]

    The shape of the outer valence (3p) photoelectron spectrum of Ar clusters is investigated by vacuum ultraviolet photoionization with synchrotron radiation. We show the dependence of the spectrum on cluster size and the change in its shape with photon energy. Inelastic losses due to intracluster photoelectron scattering are most important for changes in the photoelectron main line and explain the appearance of additional peaks. A comparison of our results to earlier work on bulk condensed Ar and Ar thin films is given. Evidence for a deviation of the photoionization cross sections for clusters from the atomic ones has not been found.

  • 23. Isvoranu, Cristina
    et al.
    Åhlund, John
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Ataman, Evren
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Andersen, Jesper N.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Schnadt, Joachim
    Electron spectroscopy study of the initial stages of iron phthalocyanine growth on highly oriented pyrolitic graphite2009In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 131, no 21, p. 214709-Article in journal (Refereed)
    Abstract [en]

    The nature of the intermolecular and substrate bonds of iron   phthalocyanine adsorbed on highly oriented pyrolitic graphite has been   investigated by x-ray photoelectron spectroscopy and x-ray absorption   spectroscopy. We find that the molecules grow in a highly ordered   fashion with the molecules essentially plane-parallel to the surface in   both the mono- and multilayers. The spectra obtained on both types of   film are virtually identical, which shows that the bonds both between   the adsorbate and substrate and between the molecular layers have a   pure van der Waals nature. Supporting density functional theory results   indicate that the layers are stabilized by weak hydrogen bonds within   the molecular layers.

  • 24.
    Jafri, Hassan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics.
    Carva, Karel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Materials Theory.
    Widenkvist, Erika
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Blom, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Sanyal, Biplab
    Fransson, Jonas
    Eriksson, Olle
    Jansson, Ulf
    Grennberg, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Karis, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics.
    The effect of induced vacancy defects on resistivity of graphene2009In: Scandem conference, Reykjavik 2009, 2009Conference paper (Refereed)
  • 25.
    Jafri, Syed Hassan Mujtaba
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Carva, Karel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    Widenkvist, Erika
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Blom, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    Fransson, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Grennberg, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Karis, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Quinlan, Ronald A
    College of William and Mary, Williamsburg VA, USA.
    Holloway, Brian C
    Luna Innovations, Danville, VA, USA.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Conductivity engineering of graphene by defect formation2010In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 43, no 4, p. 045404-Article in journal (Refereed)
    Abstract [en]

    Transport measurements have revealed several exotic electronic properties of graphene. The possibility to influence the electronic structure and hence control the conductivity by adsorption or doping with adatoms is crucial in view of electronics applications. Here, we show that in contrast to expectation, the conductivity of graphene increases with increasing concentration of vacancy defects, by more than one order of magnitude. We obtain a pronounced enhancement of the conductivity after insertion of defects by both quantum mechanical transport calculations as well as experimental studies of carbon nano-sheets. Our finding is attributed to the defect induced mid-gap states, which create a region exhibiting metallic behaviour around the vacancy defects. The modification of the conductivity of graphene by the implementation of stable defects is crucial for the creation of electronic junctions in graphene-based electronics devices.

  • 26. Johansson, E. M. J.
    et al.
    Odelius, M.
    Gorgoi, M.
    Karis, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Ovsyannikov, R.
    Schafers, S.
    Svensson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Valence Electronic Structure Of Ruthenium Based Complexes Probed By Photoelectron Spectroscopy At High Kinetic Energy (Hike) And Modeled By Dft Calculations2008In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 464, no 4-6, p. 192-197Article in journal (Refereed)
    Abstract [en]

    The valence electronic structure of a series of molecular films containing ruthenium polypyridine complexes has been investigated by photoelectron spectroscopy (PES) at high kinetic energy (HIKE) using hard X-ray. The experiment shows the possibility to experimentally probe the metal contribution to the valence spectra in a bulk sensitive mode. Specifically to directly follow the Ru 4d contribution to the highest occupied molecular orbitals of such complexes. The experimental spectra are accurately modeled by DFT calculations only if a crystal structure environment is taken into account showing the importance of intermolecular interaction for modeling the electronic structure of such complexes.

  • 27.
    Johansson, E. M. J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Plogmaker, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Walle, L. E.
    Schölin, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Borg, A.
    Sandell, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Comparing Surface Binding of the Maleic Anhydride Anchor Group on Single Crystalline Anatase TiO2 (101), (100), and (001) Surfaces2010In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 114, no 35, p. 15015-15020Article in journal (Refereed)
    Abstract [en]

    We report on the surface binding of the maleic anhydride (C4H2O3, MA) on the TiO2 anatase (101), (100), and (001) single crystal surfaces. The MA anchor group has recently been used for dye adsorption in solar cells based on nanostructured anatase, and the results reported here are partly discussed with respect to such systems. MA was deposited simultaneously onto the (101), (100), and (001) TiO2 single crystal surfaces in UHV, and the surface binding was investigated with electron spectroscopy. The O1s and C1s core-level spectra were compared to a multilayer of MA to investigate the differences in bonding to the anatase surfaces. The results suggest a surface chemistry where the molecule reacts and the MA ring opens when adsorbed at the (101) and (100) surfaces. The molecule anchors via four oxygen atoms, similar to bonding with two carboxylic groups on TiO2. For the (001) surface, the spectra indicated a different adsorption geometry. A small amount of electronic states in the bandgap of the TiO2 surfaces was observed both before and after MA was deposited onto the surfaces, and on the (101) and (100) surfaces, the intensity of these surface states was slightly enhanced after deposition of MA.

  • 28.
    Karis, Olof
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Svensson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Rusz, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Materials Theory.
    Oppeneer, Peter M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Materials Theory.
    Gorgoi, M.
    Schäfers, F.
    Braun, W.
    Eberhardt, W.
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    High-kinetic-energy photoemission spectroscopy of Ni at 1s: 6-eV satellite at 4 eV2008In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 78, no 23, p. 233105-Article in journal (Refereed)
    Abstract [en]

    Electron correlations are responsible for many profound phenomena in solid-state physics. A classical example is the 6-eV satellite in the photoelectron spectrum of Ni. Until now the satellite structure has only been investigated at the L shell and more shallow levels. Here we report a high-kinetic-energy photoemission spectroscopy (HIKE) investigation of Ni metal. We present 1s and 2p photoelectron spectra, obtained using excitation energies up to 12.6 keV. Our investigation demonstrates that the energy position of the satellite relative to the main line is different for the 1s and the 2p levels. In combination with electronic structure calculations, we show that this energy shift is attributed to unique differences in the core-valence coupling for the K and L2,3 shells in 3d transition metals, resulting in different screening of the core holes.

  • 29.
    Karlsson, E. B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Materials Physics.
    Siegbahn, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Introduction to Kai Siegbahn's memorial issue2009In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 601, no 1-2, p. 1-7Article in journal (Refereed)
    Abstract [en]

    Kai Siegbahn is mainly known to the afterworld for his development of spectroscopies which have provided a detailed understanding of the electronic structure of atoms, molecules and condensed matter. These spectroscopies are based on the discoveries made by him and his collaborators in the beginning of the 1960s which led to a Nobel prize in physics for Kai in 1981. The collection of papers in the present volume illustrate the present status of the many flourishing aspects of electron spectroscopy which have developed as a result of his initial ideas and their background in nuclear physics experimentation. (C) 2009 Elsevier B.V. All rights reserved.

  • 30.
    Lawniczak-Jablonska, Krystyna
    et al.
    Polish Academy of Sciences, Warsaw.
    Wolska, Anna
    Polish Academy of Sciences, Warsaw.
    Bak-Misiuk, Jadwiga
    Polish Academy of Sciences, Warsaw.
    Dynowska, Elzbieta
    Polish Academy of Sciences, Warsaw.
    Romanowski, Przemyslaw
    Polish Academy of Sciences, Warsaw.
    Domagala, Jaroslaw Z.
    Polish Academy of Sciences, Warsaw.
    Minikayev, Roman
    Polish Academy of Sciences, Warsaw.
    Wasik, Dariusz
    University of Warsaw.
    Klepka, Marcin T.
    Polish Academy of Sciences, Warsaw.
    Sadowski, Janusz
    Polish Academy of Sciences, Warsaw.
    Barcz, Adam
    Polish Academy of Sciences, Warsaw.
    Dluzewski, Piotr
    Polish Academy of Sciences, Warsaw.
    Kret, Sławomir
    Polish Academy of Sciences, Warsaw.
    Twardowski, Andrzej
    University of Warsaw.
    Kamińska, Maria
    University of Warsaw.
    Persson, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Arvanitis, Dimitri
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Holub-Krappe, Elisabeth
    Helmholtz Centre Berlin for Materials and Energy.
    Kwiatkowski, Adam
    University of Warsaw.
    Structural and magnetic properties of the molecular beam epitaxy grown MnSb layers on GaAs substrates2009In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 106, no 8, p. 083524-Article in journal (Refereed)
    Abstract [en]

    The structural and magnetic properties of MnSb layers grown on two   differently oriented GaAs substrates are reported. The MnSb compounds   grow nonhomogenously both on GaAs (111) B and on GaAs (100) substrates.   In x-ray diffraction studies the formation of two epitaxial domains is   observed depending on the crystallographic orientation of the   substrate. The observed diffusion of Ga atoms from the substrate to the   layers results in the formation of an additional Mn-rich cubic phase of   GaMnSb. In the case of the (100) oriented substrate, the diffusion of   Mn into the substrate was additionally found. Traces of other phases   were also noticed. The complex morphology of the layers is found to   influence their magnetic properties. Magnetic force microscopy images   revealed an inhomogenous distribution of the magnetic force gradient on   the surface and the formation of magnetic domains in the samples. X-ray   absorption studies of the chemical bonding and local atomic structure   around Mn atoms confirmed high structural and chemical disorder in the   samples. The chemical bonding of the dominating fraction of Mn atoms is   found, however, similar to that in the reference MnSb powder. The x-ray   magnetic circular dichroism measurements reveal an enhanced orbital   moment and a reduced spin moment, which is most likely caused by the   presence of different phases and a Mn-rich surface in the investigated   samples.

  • 31.
    Lewin, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Gorgoi, Mihaela
    Schäfers, Franz
    Svensson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Influence of sputter damage on the XPS analysis of metastable nanocomposite coatings2009In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 204, no 4, p. 455-462Article in journal (Refereed)
    Abstract [en]

    X-ray photoelectron spectroscopy (XPS) is a standard method of determining chemical bonding in e.g. nanocomposites. We demonstrate that sputter-cleaning of the sample prior to analysis can substantially alter the attained information. We present an in-depth analysis of sputter damage on binary and ternary TiC-based coatings in the Ti–Ni–C system. XPS was performed after sputter etching with different ion energies (0.15–4 keV). Results are compared to data from the bulk of undamaged samples attained using high kinetic energy XPS. We observe substantial sputter damage, strongly dependent on sputter energies and coating stability. Metastable samples exhibit severe sputter damage after etching with 4 keV. Additional samples from other Ti–Me–C (Me = Al, Fe, Cu or Pt) systems were also examined, and notable sputter damage was observed. This suggests that accurate analysis of any metastable nanocomposite requires careful consideration of sputter damages.

  • 32.
    Lindblad, A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Bergersen, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Pokapanich, W.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Tchaplyguine, M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Öhrwall, G.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Björneholm, O.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Charge delocalization dynamics of ammonia in different hydrogen bonding environments: free clusters and in liquid water solution2009In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 11, no 11, p. 1758-1764Article in journal (Refereed)
    Abstract [en]

    Valence and core level photoelectron spectra and Auger electron spectra of ammonia in pure clusters have been measured. The Auger electro  spectra of gas-phase ammonia, pure ammonia clusters and ammonia in   aqueous solution are compared and interpreted via ab initio calculations of the Auger spectrum of the ammonia monomer and dimer. The calculations reveal that the final two-hole valence states can be   delocalized over both ammonia molecules. Features at energies   pertaining to delocalized states involving one, or more, hydroge  bonding orbitals can be found in both the ammonia cluster Auger   electron spectrum and in that of the liquid solvated molecule. The lower Coulombic repulsion between two delocalized valence final state holes gives higher kinetic energy of the Auger electrons which is also   observed in the spectra. This decay path-specific to the condensed   phase-is responsible for more than 5% of the total cluster Auger intensity. Moreover, this interpretation is also applicable to the   solid phase since the same features have been observed, but not assigned, in the Auger spectrum of solid ammonia.

  • 33.
    Lindblad, A
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Winkler, M.
    Tchaplyguine, M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Öhrwall, G.
    Svensson, S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Björneholm, O.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    The geometric structure of pure SF6 and mixed Ar/SF6 clusters investigated by core level photoelectron spectroscopy2009In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 603, no 3, p. 433-436Article in journal (Refereed)
    Abstract [en]

    The S 2p core level photoelectron spectra of Sulphurhexafluoride   Clusters have been investigated together with heterogeneous Ar/SF6 clusters, created by doping Ar host clusters (with a mean size of 3600   atoms) with the molecule. Surface and bulk features are resolved both   in the argon 2p and the sulphur 2p core level photoelectron spectra.  For the latter level such features were only observed in the pure   cluster case; a single feature characterizes the S 2p core level  spectra of SF6 doped argon clusters. From the chemical shifts,  investigated with respect to SF6 doping pressure. It can be concluded   that the host clusters get smaller with increasing doping pressures and  that the SF6 molecules predominantly stay below the cluster surface,   whereas the Argon core stays intact. We have neither observed features   corresponding to SF6 on the cluster Surface, nor features corresponding   to molecules deep inside the bulk in any of the spectra from the pick-up experiments.

  • 34.
    Lundwall, M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Öhrwall, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Svensson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Neighbor-induced photoelectron recapture in argon clusters: A  photon-energy-dependent study of Auger spectra2008In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 78, no 6, p. 065201-Article in journal (Refereed)
    Abstract [en]

    A photon-energy-dependent experimental study of the L2,3M2,3M2,3 Auger transitions in argon clusters is presented, and features without atomic counterparts are observed in the spectra up to photon energies at least 30 eV above the L2,3 threshold. We propose that these features are due to the process of neighbor-induced recapture, in which the outgoing photoelectron is backscattered by neighboring atoms in the cluster, loses energy in a Bremsstrahlung-like inverse photoemission process, and is recaptured in a Rydberg orbital of the core-ionized atom before Auger decay.

  • 35.
    Malmgren, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Gorgoi, M
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Non-destructive depth-profiling of the SEI on different anode and cathode materials for Li-ion batteries2009In: Lithium Battery Discussion Electrode Materials, Bordeaux-Arcachon, France, 20-25 September 2009, 2009, p. O38-Conference paper (Refereed)
  • 36. Marinado, Tannia
    et al.
    Hagberg, Daniel P.
    Hedlund, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Johansson, Erik M. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Surface and Interface Science.
    Brinck, Tore
    Sun, Licheng
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Rhodanine dyes for dye-sensitized solar cells: spectroscopy, energy levels and photovoltaic performance2009In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 11, no 1, p. 133-141Article in journal (Refereed)
    Abstract [en]

    Three new sensitizers for photoelectrochemical solar cells were synthesized consisting of a triphenylamine donor, a rhodanine-3-acetic acid acceptor and a polyene connection. The conjugation length was systematically increased, which resulted in two effects: first, it led to a red-shift of the optical absorption of the dyes, resulting in an improved spectral overlap with the solar spectrum.Secondly, the oxidation potential decreased systematically. The excited state levels were, however, calculated to be nearly stationary. The experimental trends were in excellent agreement with density functional theory (DFT) comput