Change search
Refine search result
12 1 - 50 of 69
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1. Duda, L.
    et al.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Reihl, B.
    Yeom, H. W.
    Hara, S.
    Yoshida, S.
    Angle-resolved photoemission studies of the 3C-SiC(001)(2 x 1) surface1999In: Surface Review and Letters 6, 1151 (1999)Article in journal (Refereed)
  • 2. Duda, L.
    et al.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Reihl, B.
    Yeom, H. W.
    Hara, S.
    Yoshida, S.
    Electronic structure of the 3C-SiC(001)2 x 1 surface studied with angle-resolved photoelectron spectroscopy1999In: Surface Science 439, 199 (1999)Article in journal (Refereed)
  • 3. Duda, L.
    et al.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Reihl, B.
    Yeom, H. W.
    Hara, S.
    Yoshida, S.
    Surface states of the 3C-SiC(001)-c(4×2) surface studied with angle-resolved photoemission2000In: Physical. Review B 61, R2460 (2000)Article in journal (Refereed)
  • 4. Dütemeyer, T.
    et al.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Quitmann, C.
    Reihl, B.
    Imaging of the electronic states on the Si(111)1×1-As surface using a display-type photoelectron analyzer2001In: Surface Science 482-485, 600 (2001)Article in journal (Refereed)
    Abstract [en]

    e have measured the electronic structure of the arsenic-terminated Si(1 1 1)1×1As surface with angle-resolved photoemission using a display-type analyzer. The analyzer records energy-resolved angular distribution patterns of the photoelectrons in a solid angle of ?=43° and ?=360°, thereby covering the entire surface Brillouin zone at the binding energies measured here. Using this instrument we have mapped the entire two-dimensional dispersion of the lone-pair surface state, from the band maximum at to the global minima at the -points. In addition, the two-dimensional dispersions of the three upper valence bands are mapped, showing their threefold symmetry, using a photon energy of 21.2 eV. Our results are in good agreement with previous experiments and earlier quasiparticle band structure calculations

  • 5. Dütemeyer, T.
    et al.
    Quitmann, C.
    Kitz, M.
    Dörnemann, K.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Reihl, B.
    Photoelectron Imaging using an Elliptical Display Analyzer2001In: Review of Scientific Instruments 72, 2638 (2001)Article in journal (Refereed)
  • 6.
    Emanuelsson, Christian
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Johansson, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Zhang, Hanmin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Delicate Interactions of PTCDI molecules on Ag/Si(111)-√3×√32018In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 149, no 16, p. 164707-Article in journal (Refereed)
    Abstract [en]

    PTCDI molecules were evaporated onto a Ag/Si(111)√3×√3 surface and studied using scanning tun-resolution STM images are used to identify the delicate molecule/molecule and molecule/substrate interactions and the shapes of the molecular orbitals. The results show that the substrate/molecule interaction strongly modifies the electronic configuration of the molecules as their orbital shapes are quite different at 1 and 2 monolayer (ML) coverage. Simple models of molecular HOMO/LUMO levels and intermolecular hydrogen-bondings have been made for 1 and 2 ML PTCDI coverages to explain the STM images. Changes due to the interaction with the substrate are also found in ARUPS as extra states above the regular HOMO level at 1 ML PTCDI coverage. The ARUPS data also show that the electronic structure of the substrate remains unchanged after the deposition of molecules as the dispersion of the substrate related bands is unchanged. The changes in electronic structure ofthe molecules are discussed based on aHOMO/LUMO split.

  • 7.
    Emanuelsson, Christian
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Johansson, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Zhang, Hanmin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Photoelectron spectroscopy studies of PTCDI on Ag/Si(111)-root 3 x root 32018In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 149, no 4, article id 044702Article in journal (Refereed)
    Abstract [en]

    3,4,9,10-perylene tetracarboxylic diimide molecules were evaporated onto a Ag/Si(111)-root 3 x root 3 surface and studied using photoelectron spectroscopy and near edge X-ray absorption fine structure (NEXAFS). All core levels related to the imide group of the molecules showed a partial shift to lower binding energies at low coverages. In NEXAFS spectra, the first transitions to the unoccupied states were weaker at low coverages compared to thicker films. Also, extra states in the valence band between the regular highest occupied molecular orbital and the Fermi level were found at low coverages. These changes were explained by two types of molecules. Due to charge transfer from the surface, these two types have different interactions between the imide group and the substrate. As a result, one type has a partially filled lowest unoccupied molecular orbital while the other type does not. Published by AIP Publishing.

  • 8.
    Emanuelsson, Christian
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Johansson, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Zhang, Hanmin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Photoelectron spectroscopy studies of PTCDI on Sn/Si(111)-2√3×2√3Manuscript (preprint) (Other academic)
  • 9.
    Emanuelsson, Christian
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Soldemo, Markus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Johansson, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Zhang, Hanmin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Scanning tunneling microscopy study of PTCDI on Sn/Si(111)-2√3×2√32019In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 150, no 4Article in journal (Refereed)
    Abstract [en]

    Perylene tetracarboxylic diimide molecules were evaporated onto a Sn/Si(111)-2 root 3 x 2 root 3 surface and studied using scanning tunneling microscopy (STM) and low energy electron diffraction. At low coverages, single molecules are locked into specific adsorption geometries, which are investigated in detail using high resolution STM. The electronic structure of these individual molecules was studied using bias dependent STM images. The molecules form 1D rows that become more common with increasing coverages. Possible intermolecular O center dot center dot center dot H interactions within the rows have been identified. At around half of a monolayer (ML), the rows of molecules interact with each other and form a commensurate 4 root 3 x 2 root 3 reconstruction. In a complete monolayer, several structures emerge as molecules fill in the space between the 4 root 3 x 2 root 3 stripes. Possible intermolecular interactions within the 1 ML structures have been discussed. At coverages above 1 ML, the growth is characterized by island growth, where the molecules are arranged according to the canted structure within the layers.

  • 10.
    Emanuelsson, Christian
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Zhang, Hanmin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Moons, Ellen
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Johansson, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Scanning tunneling microscopy study of thin PTCDI films on Ag/Si(111)-root 3 x root 32017In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 146, no 11, article id 114702Article in journal (Refereed)
    Abstract [en]

    3,4,9,10-perylene tetracarboxylic diimide molecules were evaporated onto a Ag/Si(111)-root 3 x root 3 surface and studied by scanning tunneling microscopy/spectroscopy and low energy electron diffraction (LEED). The growth mode was characterized as layer-by-layer growth with a single molecular unit cell in a short range order. The growth of the first two monolayers involves a molecule/substrate superstructure and a molecule/molecule superstructure. At higher coverages, the molecules in each layer were found to align so that unit cells are on top of each other. The experimentally obtained LEED pattern is described as a combination of patterns from the molecular unit cell and the molecule/substrate superstructure. The electronic structure was found to be strongly dependent on the film thickness for the first few layers: Several extra states are found at low coverages compared to higher coverages resulting in a very small pseudo gap of 0.9 eV for the first layer, which widens up to 4.0 eV for thicker films.

  • 11. Grehk, T.M.
    et al.
    Götelidh, M.
    Karlsson, U.O.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Gray, S.M.
    Magnusson, Kjell
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    The clean and Cs-exposed Si(111)3x3:B surface studied with photoemission1995In: Phys. Rev. B52, 11165 (1995)Article in journal (Refereed)
  • 12. Gunnella, R.
    et al.
    Yeom, H. W.
    Bullock, E. L.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Kono, S.
    Solal, F.
    Study of Si 2p core-level shift at the As/Si(001)-2×1 surface2002In: Surface Science 499, 244 (2002)Article in journal (Refereed)
    Abstract [en]

    The atomic origin of the photoemission Si 2p core level, shifted at 0.35 eV higher binding energy, at the As/Si(0 0 1)-2×1 surface, is investigated. The study is based on the determination of the surface structure by means of multiple scattering analysis of As 3d azimuth photoelectron diffraction (PD) patterns. The obtained structure is used to assign the atomic origin of the Si 2p component by surface core level shift PD. We find that a single atom contributes to the core level, while, on the basis of final state calculations, a contribution from two different atoms would be expected

  • 13. Gurnett, Michael
    et al.
    Gustafsson, Jörgen
    Holleboom, Thijs Jan
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Magnusson, Kjell
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Widstrand, Susanna
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Johansson, M.K.-J.
    Gray, S.M.
    Core-level spectroscopy study of the Li/Si(111)-3x1, Na/Si(111)-3x1 and K/Si(111)-3x1 surfaces2005In: Phys. Rev. B 71, 195408 (2005)Article in journal (Refereed)
  • 14. Gurnett, Michael
    et al.
    Gustafsson, Jörgen
    Magnusson, Kjell
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Widstrand, Susanna
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Angle-resolved photoemission study of the single-domain Si(111) 3×1/6×1 -Ag surface2002In: Phys. Rev. B 66, 161101 (R) (2002)Article in journal (Refereed)
  • 15.
    Gurnett, Michael
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Holleboom, Thijs
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science.
    Zhang, Hanmin
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Photoemission study of the Li/Ge(111)-3×1 reconstruction2009In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, ISSN 0039-6028, Vol. 603, no 4, p. 727-735Article in journal (Refereed)
    Abstract [en]

    In this article we report our findings on the electronic structure of the Li induced Ge(1 1 1)–3 × 1reconstruction as determined by angle-resolved ultraviolet photoelectron spectroscopy (ARUPS) and core-level spectroscopy using synchrotron radiation. The results are compared to the theoretical honeycomb-chain-channel (HCC) model for the 3 × 1reconstruction as calculated using density functional theory (DFT). ARUPS measurements were performed in both the and directions of the 1 × 1 surface Brillouin zone at photon energies of 17 and 21.2 eV. Three surface related states were observed in the direction. In the direction, at least two surface states were seen. The calculated band structure using the single-domain HCC model for Li/Ge(1 1 1)–3 × 1 was in good agreement with experiment, allowing for the determination of the origin of the experimentally observed surface states. In the Ge core-level spectra, two surface related components were identified, both at lower binding energy with respect to the Ge bulk peak. Our DFT calculations of the surface core-level shifts were found to be in fair agreement with the experimental results. Finally, in contrast to the Li/Si(1 1 1)–3 × 1 case, no double bond between Ge atoms in the top layer was found

  • 16. Gustafsson, Jörgen
    et al.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Widstrand, Susanna
    Gurnett, Michael
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Thin PTCDA Films on Si(001) II: Electronic Structure2004In: Surface Science 572, 32 (2004)Article in journal (Refereed)
    Abstract [en]

    We have studied the thin film formation and the electronic structure of the organic molecular semiconductor 3,4,9,10 perylene tetracarboxylic dianhydride (PTCDA), on clean and on hydrogen-passivated Si(0 0 1) surfaces. The studies were made by means of high resolution X-ray photoelectron spectroscopy (HRXPS), angle-resolved photoelectron spectroscopy (ARPES), near edge X-ray absorption fine structure (NEXAFS) and low energy electron diffraction (LEED). On the H passivated surface the changes in the electronic structure of the substrate and the molecules with increasing film thickness are very small. The molecular orbitals show a dispersive behavior, indicating that the PTCDA layers are ordered. On the reactive clean surface the anhydride groups of the molecule interact with the substrate as indicated by changes in the core level binding energies. This results in a much lower ordering in the film compared to PTCDA on a passivated silicon surface. There is no sign of decomposition of the molecule because of the more reactive substrate

  • 17. Gustafsson, Jörgen
    et al.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Widstrand, Susanna
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Thin PTCDA Films on Si(001) I: Growth Mode2004In: Surface Science 572, 23 (2004)Article in journal (Refereed)
    Abstract [en]

    We have studied the interface and thin film formation of the organic molecular semiconductor 3,4,9,10 perylene tetracarboxylic dianhydride (PTCDA) on clean and on hydrogen passivated Si(0 0 1) surfaces. The studies were made by means of high resolution X-ray photoelectron spectroscopy (HRXPS), near edge X-ray absorption fine structure (NEXAFS), low energy electron diffraction (LEED), and atomic force microscopy (AFM). On the passivated surface the LEED pattern is somewhat diffuse but reveals that the molecules grow in several ordered domains with equivalent orientations to the substrate. NEXAFS shows that the molecules are lying flat on the substrate. The Si 2p XPS line shape is not affected when the film is deposited so it can be concluded that the interaction at the interface between PTCDA and the substrate is weak. The evolution of the film formation appears to be homogeneous for the first monolayer with a nearly complete coverage of flat lying molecules based on the XPS attenuation. For layer thickness of 0.52 monolayers (ML) the molecules start to form islands, attracting the molecules in between, leaving the substrate partly uncovered. For thicker films there is a StranskiKrastanov growth mode with thick islands and a monolayer thick film in between. For the clean surface the ordering of the film is much lower and angle resolved photoelectron spectroscopy (ARPES) of the molecular orbitals have only a small dependence of the emission angle. NEXAFS shows that the molecules do not lie flat on the surface and also reveal a chemical interaction at the interface

  • 18. Gustafsson, Jörgen
    et al.
    Widstrand, Susanna
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Growth and characterization of thin PTCDA films on 3C-SiC(001)c(2x2)2006Article in journal (Refereed)
  • 19.
    Gustafsson, Jörgen
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Zhang, Hanmin
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    STM studies of thin PTCDA films on Ag/Si(111) )-sqrt3×sqrt32007In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 75, p. 155414-1-155414-7Article in journal (Refereed)
  • 20. Gustafsson, Jörgen
    et al.
    Zhang, Hanmin
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Electron spectroscopy studies of PTCDA on Ag/Si(111) )- √3 × √32007In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 75, no 15, p. 155413-Article in journal (Refereed)
  • 21. Heister, K.
    et al.
    Rong, H.-T.
    Buck, M.
    Zharnikov, M.
    Grunze, M.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Odd-even efffects at the S-metal interface and in the aromatic matrix in biphenyl-substituted alkanethiol self-assembled monolayers2001In: Journal of Physical Chemistry B 105, 6888 (2001)Article in journal (Refereed)
    Abstract [en]

    Synchrotron-based high-resolution X-ray photoelectron spectroscopy was applied to characterize self-assembled monolayers (SAM) of biphenyl-substituted alkanethiols CH3(C6H4)2(CH2)nSH (BPn, n = 1-4) on Au and Ag substrates. Beyond previously identified odd-even changes in the packing density and the tilt angle of the biphenyl moieties, the high-resolution spectra reveal a number of additional odd-even effects upon variation of the number of methylene groups in the aliphatic part in the BPn molecule. Their occurrence and mutual correlation suggests that a BPn SAM represents a strongly correlated, highly ordered molecular assembly. In particular, periodical changes of a shake up feature in the C 1s region are observed, which are related to the differences in the arrangement of the aromatic matrix. The width and binding energy position of the S 2p signals also exhibit odd-even changes. The width changes are associated with the occupation of either equivalent or nonequivalent adsorption sites on the polycrystalline (111) Au and Ag substrates. The comparison of the width values with those for conventional alkanethiols implies that the substrate bonding of alkanethiols on gold cannot be described by a single adsorption site

  • 22. Heister, K.
    et al.
    Zharnikov, M.
    Grunze, M.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Adsorption of alkanethiols and biphenylthiols on Au and Ag substrates: A high resolution X-ray photoelectron spectroscopy study2001In: Journal of Physical Chemistry B 105, 4058 (2001)Article in journal (Refereed)
    Abstract [en]

    Synchrotron-based high-resolution X-ray photoelectron spectroscopy was applied to monitor the formation of self-assembled monolayers (SAM) of alkanethiols (AT) and biphenylthiols on Au and Ag substrates. Pronounced chemical shifts in the adsorbate- and substrate-related photoemission lines upon SAM formation were observed. Only one sulfur species could be detected in the S 2p spectra of the investigated SAMs, consistent with a thiolate bond. From the fwhm's of the core level photoemission spectra conclusions on the heterogeneity of the adsorption sites and adsorption geometry can be made. The experimental data imply several (at least two) slightly different adsorption geometries for the AT moieties in AT/Au. Significant final state effects in the C 1s photoemission were found for both the aliphatic and aromatic SAMs

  • 23. Heister, K.
    et al.
    Zharnikov, M.
    Grunze, M.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Ulman, A.
    Characterization of X-ray induced damage in alkanethiolate monolayers by high resolution photoelectron spectroscopy,2001In: Langmuir 17, 8 (2001)Article in journal (Refereed)
    Abstract [en]

    Synchrotron-based high-resolution X-ray photoelectron spectroscopy was for the first time applied to investigate the damage in self-assembled monolayers (SAMs) of alkanethiols (AT) on Au caused by soft X-rays. The observed changes in AT SAMs and, in particular, the appearance of a new, irradiation-induced sulfur species are identical to those caused by electron bombardment, implying that most of the damage is produced by the photoelectrons and secondary electrons. The irradiation-induced sulfur species is identified as a dialkyl sulfide distributed within the AT film. Only minutes of monochromatized X-ray irradiation at an undulator beamline destroys the AT adlayer completely.

  • 24. Heister, Karin
    et al.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Grunze, Michael
    Zharnikov, Michael
    A detailed Analysis of the C 1s Photoemission of n-Alkanethiolate Films on Noble Metal Substrates2003In: Surface Science, 529, 36 (2003)Article in journal (Refereed)
    Abstract [en]

    High-resolution C 1s X-ray photoemission spectra for the series of n-alkanethiolate (AT) self-assembled monolayers (SAMs) with different lengths of the alkyl chain have been acquired and analyzed in terms of initial and final state effects and fine structure of the C 1s emission. Independent of the alkyl chain length, the binding energy position of this emission was found to be higher by ?0.35 eV for AT SAMs on Ag substrate as compared to Au, which was attributed to the differences in the final state screening mediated by the intermolecular charge transfer. It was assumed that the extent of this effect is a function of the detailed molecular arrangement in the alkyl matrix and demonstrated that the difference in the C 1s peak position disappears as soon as this arrangement is distorted by the incorporation of sulfone moiety in the alkyl chain. In addition, a change of the C 1s peak shape from a symmetric to asymmetric line with increasing alkyl chain length has been observed. This development could be described assuming the existence of a fine structure in the C 1s emission, with two low-intensity components at the higher and lower BE sides of the main emission peak. An assignment of these components has been considered

  • 25.
    Hirvonen Grytzelius, Joakim
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Zhang, Hanmin
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Core-level spectroscopy studies of Mn/Si(111)-sqrt3xsqrt32008Conference paper (Refereed)
  • 26.
    Hirvonen Grytzelius, Joakim
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Zhang, Hanmin
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Coverage dependence and surface atomic structure of Mn/Si(111)-√3×√3 studied by scanning tunneling microscopy and spectroscopy2009In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 80, p. 235324-1-235324-6Article in journal (Refereed)
    Abstract [en]

    Thin manganese silicide films of different thicknesses on Si(111) have been studied in detail by low-energy electron diffraction (LEED), scanning tunneling microscopy, and scanning tunneling spectroscopy (STM/STS). Up to a Mn coverage of 3–4 monolayers (ML), island formation is favored. For higher Mn coverages up to 12 ML uniform film growth is found. The silicide film morphology at low coverages supports a layered Mn-Si film structure. The silicide surfaces displayed a √3×√3 LEED pattern. STM images recorded from the √3×√3 surfaces mostly show a hexagonal pattern but a honeycomb pattern has also been observed. A surface atomic structure based on chained Mn triangles is proposed. Our STM results are in good agreement with a recent theoretical model. The high-quality STS spectra recorded from the different surfaces show a clear metallic character at 1.5 ML and higher coverages. The filled-state features in the STS spectra at surfaces with 3–4 ML Mn coverages are similar to earlier published angle-resolved photoelectron spectroscopy data.

  • 27.
    Hirvonen Grytzelius, Joakim
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Zhang, Hanmin
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Electronic structure of Mn/Si(111)-sqrt3xsqrt32007Conference paper (Refereed)
  • 28.
    Hirvonen Grytzelius, Joakim
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Zhang, Hanmin
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Mn5Ge3 film formation on Ge(111)c(2×8)2012In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 86, no 12, p. 125313-1-125313-7Article in journal (Refereed)
    Abstract [en]

    Thin manganese germanide films with different thicknesses on Ge(111) have been studied in detail by low-energy electron diffraction (LEED), scanning tunneling microscopy, and core-level spectroscopy (CLS). Annealing of the deposited Mn on Ge(111)c(2×8) between 330-450 C resulted in well-ordered Mn5Ge3 surfaces as seen by intense 3×3 LEED spots. Up to a coverage of 24 monolayers (ML), island formation is favored. At a coverage of 32 ML a well ordered Mn5Ge3 film was found to fully cover the surface. High-resolution Ge 3d CLS spectra were recorded with photon energies between 50 and 110 eV at normal and 60 emission angles. In contrast to earlier results, three components have been used in the line-shape analysis to achieve a consistent fit over the energy and angular range. In addition, three components have been identified for the Mn 2p CLS spectra. The two major components fit well with a layered Mn germanide structure suggested in the literature.

  • 29.
    Hirvonen Grytzelius, Joakim
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Zhang, Hanmin
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Surface atomic and electronic structure of Mn5Ge3 on Ge(111)2011In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, ISSN 1098-0121, Vol. 84, no 19, p. 195306-1-195306-6Article in journal (Refereed)
    Abstract [en]

    The atomic and electronic structure of the Mn5Ge3(001) surface grown on Ge(111) c(2×8) has been studied in detail by angle-resolved photoelectron spectroscopy (ARPES), scanning tunneling microscopy (STM), and scanning tunneling spectroscopy. ARPES spectra recorded from the Γ̅ -K̅ -M̅ and Γ̅ -M̅ -Γ̅ directions of the surface Brillouin zone show six surface-related features. The STM images recorded at biases higher/lower than ±0.4 V always show a honeycomb pattern with two bright protrusions in each unit cell. At lower biases, a hexagonal, intermediate transition, and a honeycomb pattern are observed. These can be explained as arising from Mn and Ge atoms in the sublayer arranged in triangular structures and Mn atoms in the top layer arranged in a honeycomb structure, respectively. The photoemission and STM data from the germanide surface are discussed and compared to earlier published theoretical, photoelectron spectroscopy, and scanning tunneling microscopy studies.

  • 30.
    Hirvonen Grytzelius, Joakim
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Zhang, Hanmin
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Surface electronic structure of Mn/Si(111)-√3×√32008In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 78, no 15, p. 155406-1-155406-6Article in journal (Refereed)
    Abstract [en]

    The Mn/Si(111)-√3×√3 surface has been studied in detail by low energy electron diffraction (LEED), angle-resolved photoelectron spectroscopy (ARPES), and core-level photoelectron spectroscopy (CLS). Annealing of the deposited manganese resulted in a well-ordered surface as seen by intense √3×√3 LEED spots. ARPES spectra recorded in the Γ̅ -K̅ -M̅ direction of the √3×√3 surface Brillouin zone show five surface related features in the band gap while in the Γ̅ -M̅ -Γ̅ direction four surface features are observed. The high-resolution Si 2p CLS data were recorded at photon energies between 108–140 eV both at normal and 60° emission angle. The bulk component was identified from the bulk sensitive spectrum recorded at a photon energy of 108 eV. To achieve a consistent core-level fitting over the whole energy and angular range, five components were introduced in the line-shape analysis. The photoemission data from the √3×√3 surface have been discussed and compared with a recent theoretical model. The findings here support a layered Mn silicide film structure.

  • 31.
    Johansson, Lars
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Duda, L.
    Laurenzis, M.
    Krieftewirth, M.
    Reihl, B.
    Electronic Structure of the 6H-SiC(0001)-3×3 Surface Studied with Angle-Resolved Inverse and Direct Photoemission2000In: Surface Science 445, 109 (2000)Article in journal (Refereed)
  • 32.
    Nilsson, Daniel
    et al.
    Department of Chemical and Biological Engineering, Chalmers University of Technology.
    Watcharinyanon, Somsakul
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Eng, Mattias
    Department of Chemical and Biological Engineering, Chalmers University of Technology.
    Li, Liqian
    Department of Chemical and Biological Engineering, Chalmers University of Technology.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Zharnikov, Michael
    Angewandte Physikalische Chemie, Universität Heidelberg.
    Shaporenko, Andrey
    Angewandte Physikalische Chemie, Universität Heidelberg.
    Albinsson, Bo
    Department of Chemical and Biological Engineering, Chalmers University of Technology.
    Mårtensson, Jerker
    Department of Chemical and Biological Engineering, Chalmers University of Technology.
    Characterization of Self-Assembled Monolayers of Oligo(phenyleneethynylene) Derivatives of Varying Shapes on Gold: Effect of Laterally Extended ∏-Systems2007In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 23, no 11, p. 6170-6181Article in journal (Refereed)
    Abstract [en]

    Fully conjugated organic molecules, such as the oligo(phenyleneethynylene) (OPE) systems, are of growing interest within the field of molecular electronics, as is the self-assembly of well-defined molecular thin films with predefined functions. The structure and function of such films are intimately related and governed by the structures of their molecular constituents, through the intermolecular interactions and the interactions between the molecules and the substrate, onto which the film is assembled. Here we report on the synthesis of a series of three OPE derivatives, with the general structure phenylethynylene−aryl−ethynylenephenylene−headgroup, and the structural investigation of the self-assembled monolayers (SAMs) formed from them on Au(111) surfaces. The SAMs were characterized by infrared reflection−absorption spectroscopy, spectroscopic ellipsometry, high-resolution X-ray photoemission spectroscopy, and near-edge X-ray absorption fine structure spectroscopy. The effective thickness of the SAMs was observed to decrease as the π-system of the aryl moiety of the OPE adsorbate was extended perpendicular to its molecular long axis. Changing the aryl moiety from benzene to naphthalene to anthracene resulted in lower molecular surface densities and larger molecular inclination. The average tilt angles for the benzene, naphthalene, and anthracene SAMs were found to be about 30°, 40°, and 42° from the surface normal, respectively. For the largest adsorbate, the anthracene derivative, there is spectroscopic evidence suggesting the existence of nonequivalent binding sites. The differences observed between the SAMs are rationalized in terms of the shape of the adsorbates and the strength of the π−π interactions between them

  • 33. Reihl, B.
    et al.
    Dudde, R.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Magnusson, Kjell
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Inverse photoemission of alkali-metal overlayers on semiconductors1993Conference paper (Refereed)
  • 34. Reihl, B.
    et al.
    Dudde, R.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Magnusson, Kjell
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    The electronic structure of alkali-metal layers on semiconductor surfaces1992In: Appl. Phys. A 55, 449 (1992)Article in journal (Refereed)
  • 35. Reihl, B.
    et al.
    Dudde, R.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Magnusson, Kjell
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Sorensen, S.L.
    Wiklund, S.
    The bonding of alkali metals to semiconductor surfaces : a direct and inverse photoemission study1992In: Appl. Surf. Sci. 56-58, 123 (1992)Article in journal (Refereed)
  • 36. Shaporenko, A
    et al.
    Adlkofer, K
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Tanaka, M
    Zharnikov, M
    Functionalization of GaAs Surfaces with Aromatic Self-Assembled Monolayers: A Synchrotron-Based Spectroscopic Study2003In: Langmuir 19, 4992 (2003)Article in journal (Refereed)
    Abstract [en]

    Stoichiometric GaAs(100) surfaces were functionalized with monolayers of an aromatic compound, 1,1'-biphenyl-4-thiol (BPT), and the engineered surfaces were studied by synchrotron-based high-resolution X-ray photoelectron spectroscopy and near edge X-ray absorption fine structure spectroscopy. BPT molecules were found to form a well-ordered and densely packed self-assembled monolayer on these substrates. The attachment to the substrate occurs over the thiolate headgroup while the intact biphenyl moieties have an upright orientation with an average tilt angle of 31.5 ± 5. The functionalization of GaAs by BPT was found to prevent an oxidation and contamination of the substrate, keeping the GaAs surface in a pristine state. The surface engineering of GaAs with functionalized aromatic monolayers can provide a crucial link for combining GaAs-based semiconductor nanostructures with bio-organic molecular assemblies

  • 37. Shaporenko, A.
    et al.
    Adlkofer, K.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Ulman, A.
    Grunze, M.
    Tanaka, M.
    Zharnikov, M.
    Spectroscopic characterization of 4´-substituted aromatic self-assembled monolayers on GaAs (100) surface2004In: Journal of Physical Chemistry B 108, 17964 (2004)Article in journal (Refereed)
    Abstract [en]

    High-resolution X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy were applied to characterize GaAs(100) surface engineered by self-assembled monolayers (SAMs) of 4'-substituted aromatic molecules: 4'-methyl-4-mercaptobiphenyl (CH3-BPT) and 4'-hydroxy-4-mercaptobiphenyl (OH-BPT). Both of these molecules formed ordered and densely packed SAMs on GaAs, which were able to protect the substrate from degradation under ambient conditions. The molecular attachment in the SAMs is mediated by As-thiolate bond while the intact aromatic backbones have an upright orientation with average tilt angles of 31.0 and 37.2 for CH3-BPT and OH-BPT films, respectively. The difference in the tilt angle is attributed to a higher (by 7-10%) packing density of the former SAM, suggesting that the character of 4'-substitution affects the quality of the resulting SAM on the GaAs substrate

  • 38. Shaporenko, A.
    et al.
    Brunnbauer, M.
    Terfort, A.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Grunze, M.
    Zharnikov, M.
    Odd-even effects in photoemission from terphenyl-substituted alkanethiolate self-assembled monolayers2005In: Langmuir 21(10), 4370 (2005)Article in journal (Refereed)
    Abstract [en]

    Self-assembled monolayers (SAMs) formed from 4,4'-terphenyl-substituted alkanethiols C6H5(C6H4)2(CH2)nSH (TPn, n = 1-6) on polycrystalline (111) gold and silver substrates have been characterized by synchrotron-based high-resolution X-ray photoelectron spectroscopy. The intensities, binding energy positions, and width of most photoemission lines exhibited pronounced odd-even effects, i.e., systematic and periodic variation, depending on either odd or even number of the methylene units in the aliphatic linker of the TPn molecules. The detailed analysis of these effects provides important information on the bonding and arrangement of the chemisorbed sulfur headgroups in the TPn films and balance of the structural forces in alkanethiolate SAMs

  • 39. Shimomura, M.
    et al.
    Munakata, M.
    Honma, K.
    Widstrand, Susanna
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Abukawa, T.
    Kono, S.
    Structural study of benzene adsorbed on Si(001) surface by photoelectron diffraction2003In: Surface Review and Letters, 10, 499 (2003)Article in journal (Refereed)
  • 40.
    Starfelt, Samuel
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Zhang, Hanmin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013). Karlstad University, Faculty of Technology and Science, Materials Science.
    Johansson, Lars
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013). Karlstad University, Faculty of Technology and Science, Materials Science.
    Quantum-well states in thin Ag films grown on the Ga/Si(111)-root 3 x root 3 surface2018In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 97, no 19, article id 195430Article in journal (Refereed)
    Abstract [en]

    Silver thin films have been created by room temperature deposition on a Ga/Si(111)-root 3 x root 3 surface and their valence band structures and core levels have been measured by angle-resolved photoelectron spectroscopy (ARPES). Discrete quantum-well states (QWSs) quantized from the Ag sp valence band are observed already at 3 monolayers (ML). The characteristics of the QWSs have been examined in the phase accumulation model for thicknesses between 3 and 12 ML. The phase shift and QWSs binding energies dependence with Ag film thicknesses have all been consistently derived. In-plane energy dispersion follows a parabolic curve, and the effective mass of the QWSs shows an increasing trend with binding energies as well as with reduced film thicknesses. Furthermore, the ARPES measurements reveal umldapp mediated QWSs around the (M)over-bar points of the Si(111) 1 x 1 surface Brillouin zone. The study confirms that the Ga/Si(111)-root 3 x root 3 surface is a good substrate for growing uniform ultrathin Ag films in room temperature conditions.

  • 41. Stoltz, D.
    et al.
    Stoltz, S. E.
    Gurnett, Michael
    Widstrand, Susanna
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Investigation of surface structure related features in the multiple scattering simulations of photoelectron diffraction of 3C-SiC(001)-c(4×2)2007In: Physica B 395, 130 (2007)Article in journal (Refereed)
  • 42. Stoltz, D.
    et al.
    Stoltz, S. E.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Surface resonance on the (63 × 63)-R30°-reconstructed 5 ML Au on 4H-SiC(0001)-(3×32007In: Surface Science 601, 2508 (2007)Article in journal (Refereed)
  • 43. Stoltz, D.
    et al.
    Stoltz, S. E.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Two-dimensional states in the electronic structure of Au/(3×3)R30°-4H-SiC(0001)2008In: Journal of Electron Spectroscopy and Related Phenomena, 163, 1 (2008)Article in journal (Refereed)
  • 44. Stoltz, D.
    et al.
    Stoltz, S.E.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    A high-resolution core-level photoemission study of the Au/4H-SiC(0001)-(3×3) interface2007In: Journal of Physics: Condensed Matter 19, 266006 (2007)Article in journal (Refereed)
  • 45.
    Watcharinyanon, Somsakul
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Johansson, Lars S.O.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Mixed Self-Assembled Monolayers of Ferrocene-Terminated and Unsubstituted Alkanethiols on Gold: Surface Structure and Work Function2009In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 113, no 5, p. 1972-1979Article in journal (Refereed)
    Abstract [en]

    Mixed self-assembled monolayers of 11-ferrocene-1-undecanethiol (FcC11) and decanethiol (C10) were prepared by two different methods: from a mixed solution and by subsequent immersion. These preparations result in self-assembled monolayers (SAMs) with different portions of FcC11 molecules, orientations, and degrees of order in the SAM. The structure of these layers was studied by high-resolution X-ray photoelectron spectroscopy (HRXPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and their effect on the surface electronic properties was investigated by Kelvin probe. The fraction of FcC11 in C10 thiol could be estimated from the intensity of the HRXPS Fe 2p3/2 peaks. The SAM prepared from the mixed solution was of high quality, and the portion of FcC11 molecules in this film was about 60%. The interaction of neighboring ferrocene moieties indicated phase separation between FcC11 and C10 species in the film. For the SAMs prepared by subsequent immersion in C10 and FcC11 solutions, the portion of FcC11 molecules varied from 35% to 55% dependent on the immersion times in the C10 solution. The degree of orientational order of the alkyl chains increased with increasing immersion time in C10. In addition, the adsorption of C10 decreased the work function of the gold surface while the adsorption of FcC11 increased this value. By varying the fraction of FcC11 in the SAMs with different preparation schemes, the work function of the gold surface could be varied in a controllable way

  • 46.
    Watcharinyanon, Somsakul
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Nilsson, Daniel
    Department of Chemical and Biological Engineering, Chalmers University of Technology.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Shaporenko, Andrey
    Angewandte Physikalische Chemie, Universität Heidelberg im Neuenheimer Feld 253.
    Zharnikov, Michael
    Angewandte Physikalische Chemie, Universität Heidelberg im Neuenheimer Feld 253.
    Albinsson, Bo
    Department of Chemical and Biological Engineering, Chalmers University of Technology.
    Mårtensson, Jerker
    Department of Chemical and Biological Engineering, Chalmers University of Technology.
    Johansson, Lars S.O.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    A spectroscopic study of self-assembled monolayer of porphyrin-functionalized oligo(phenyleneethynylene)s on gold: the influence of the anchor moiety2008In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 10, no 34, p. 5264-5275Article in journal (Refereed)
    Abstract [en]

    Porphyrin-functionalized oligo(phenyleneethynylene)s (OPE) are promising molecules for molecular electronics applications. Three such molecules (1-3) with the common structure P-OPE-AG (P and AG are a porphyrin and anchor group, respectively) and different anchor groups, viz. an acetyl protected thiol, -S-COCH3 (1), an acetyl protected thiol with methylene linker, -CH2-S-COCH3 (2), and a trimethylsilylethynyl group, -C(triple bond)C-Si(CH3)3 (3) have been synthesized and the corresponding self-assembled monolayers (SAMs) on Au(111) substrates have been prepared. The integrity and structural properties of these films were studied by X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy. The results suggest that the films formed from 1 have a high orientational order with an almost upright orientation and dense packing of the molecular constituents, i.e. represent a high quality SAM. In contrast, molecule 2 formed disordered molecular layers on Au, even though the molecule-surface bonding (thiolate) is the same as in the case of molecule 1. This suggests that the methylene linker in molecule 2 has a strong impact on the quality of the resulting film, so that a well-ordered SAM cannot be formed. The silane system, 3, is also able to bind to the gold surface but the resulting SAM has a poor quality, being significantly disordered and/or comprised of strongly inclined molecules. The above results suggest that the nature of the anchor group along with a possible linker is an important parameter which, to a high extent, predetermines the entire quality of OPE-based molecular layers

  • 47.
    Watcharinyanon, Somsakul
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Nilsson, Daniel
    Department of Chemical and Biological Engineering, Chalmers University of Technology.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Zharnikov, Michael
    Angewandte Physikalische Chemie, Universität Heidelberg, Germany.
    Shaporenko, Andrey
    Angewandte Physikalische Chemie, Universität Heidelberg, Germany.
    Albinsson, Bo
    Department of Chemical and Biological Engineering, Chalmers University of Technology.
    Mårtensson, Jerker
    Department of Chemical and Biological Engineering, Chalmers University of Technology.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    HRXPS and NEXAFS Study of Self-Assembled Monolayer of Porphyrin- Functionalized Oligo(phenyleneethynylene) on Gold: The Influence of the Binding GroupManuscript (preprint) (Other academic)
  • 48.
    Watcharinyanon, Somsakul
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Puglia, Carla
    Department of Physics and Materials Science, Uppsala University.
    Göthelid, Emmanuelle
    Department of Physics and Materials Science, Uppsala University.
    Bäckvall, Jan-E.
    Department of Organic Chemistry, Stockholm University.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Molecular orientation of thiol-derivatized tetraphenylporphyrin on gold studied by XPS and NEXAFS2009In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 603, no 7, p. 1026-1033Article in journal (Refereed)
    Abstract [en]

    Tetraphenylporphyrins bearing four linkers consisting of thioacetyl-functionalized carbon chains were immobilized on a gold surface via thiolate–gold bonds using two different preparation routes. The structure of these molecular layers was characterized in detail with synchrotron radiation based core-level spectroscopy, X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The results show that the geometry of the molecular layers and the number of linkers that bind to the gold surface depends on the preparation schemes. The deprotection of the linkers through removal of the terminal acetyl group before the molecular adsorption (deprotected systems) resulted in porphyrins bound to the gold surface with on the average three linkers, their normal axis being tilted ∼38° with respect to the surface normal. On the other hand, porphyrin layers prepared directly with the acetyl group still in place on the linkers (protected systems) are made of molecules bound to the gold surface via two linkers on the average. The resulting orientation is more upright, with the normal axis of the porphyrin plane tilted ∼50° with respect to the surface normal. Moreover, NEXAFS measurements revealed that the acetyl deprotected porphyrin layers have a higher degree of ordering than the protected systems.

  • 49. Widstrand, Susanna
    et al.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Magnusson, Kjell
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Larsson, M.I.
    Yeom, H. W.
    Hara, S.
    Yoshida, S.
    Angle-resolved photoemission study of the hydrogenated 3C-SiC(001)-2x1-H surface2001In: Surf. Sci. 479, 247 (2001)Article in journal (Refereed)
  • 50. Widstrand, Susanna
    et al.
    Magnusson, Kjell
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Johansson, Lars
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Angle-resolved photoemission from stoichiometric GaN(0001)-1x12005In: Surf. Sci, 584, 169 (2005)Article in journal (Refereed)
12 1 - 50 of 69
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf