| 1. |
- Nilsson, P. O., et al.
(author)
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Electronic structure of buried Si layers in GaAs(001) as studied by soft-x-ray emission
- 1995
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 52, s. R8643-
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Journal article (peer-reviewed)abstract
- It is demonstrated that it is possible to investigate details of the electronic structure of an internal atomic monolayer using soft-x-ray-emission spectroscopy. The local and partial density of states of one monolayer and three monolayers of Si, embedded deep below a GaAs(001) surface, was extracted. Clear differences to the density of states for bulk Si were observed.
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| 2. |
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| 3. |
- Guo, J.-H., et al.
(author)
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How the phenyle rings (benzene) act as building blocks in pi conjugated polymers
- 1998
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In: Advanced Light Source. - Berkeley : Ernest Orlando Lawrence Berkeley National Laboratory, University of California Berkeley, California, USA. ; , s. 129-132
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Book chapter (other academic/artistic)abstract
- Organic conjugated polymers have the electronic structure of semiconductors and can be doped to become good conductors (1). Conjugated polymers are now used as active materials in a wide variety of prototype applications such as light emitting diodes [2] and organic transistors [3,4]. Most of the interesting chemistry and physics of conjugated polymers is associated with the details of the electronic structure at the valence and conduction band edges and, in this connection, various electron spectroscopies can be used as tools for diagnosis of the relevant electronic and geometric properties....
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| 4. |
- Guo, J.-H., et al.
(author)
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Resonant and nonresonant x-ray scattering spectra of some poly(phenylenevinylene)s
- 1998
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In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 108:14, s. 5990-5996
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Journal article (peer-reviewed)abstract
- The electronic structure of some poly(phenylenevinylene)s have been investigated by resonant and nonresonant x-ray inelastic scattering spectroscopies. The nonresonant as well as all resonant spectra for each polymer demonstrate benzene-like features, indicating a local character of the x-ray emission in which the phenyl ring acts as a building block. Theoretical simulations of x-ray energies and intensities taking the repeat unit as a model molecule of the polymer agree with the experimental spectra fairly well. The edges of the occupied bands have been identified in the nonresonant spectra of each polymer. By subtracting the emission energy of the highest occupied molecular orbital in the nonresonant spectrum from the core excitation energy in the resonant spectrum an alternative way to determine the optical band gap is obtained. As for free benzene the outer π band in the polymer spectra show a depletion of the emission going from the nonresonant to the resonant x-ray emission spectra. It is demonstrated that this transition, which is strictly symmetry forbidden for free benzene, becomes effectively forbidden in the polymer case as a result of strong interference effects, and it is argued that this is the general case for resonant x-ray emission of conjugated polymers as far as the frozen orbital approximation holds.
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| 5. |
- Guo, J.H., et al.
(author)
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Resonant excitation x-ray-fluorescence from C-60
- 1995
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In: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 52, s. 10681-
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Journal article (peer-reviewed)abstract
- X-ray fluorescence of condensed C-60 has been recorded in high resolution using monochromatic synchrotron radiation excitation. Strong intensity modulation of constituent spectral features is observed with varying excitation energy up to 10 eV above threshold. The energy dependence is interpreted as due to resonant inelastic x-ray scattering, leading to symmetry selection rules governing the two-photon process in the fully symmetric molecule.
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| 9. |
- Butorin, S. M., et al.
(author)
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Low-Energy d-d Excitations in MnO Studied by Resonant X-ray Fluorescence Spectroscopy
- 1997
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In: Advanced Light Source. - Berkely : Ernest Orlando Lawrence Berkeley National Laboratory University of California Berkeley, California. ; , s. 135-136
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Book chapter (other academic/artistic)abstract
- Resonant soft X-ray emission spectroscopy has been demonstrated to possess interesting abilities for studies of electronic structure in various systems, such as symmetry probing, alignment and polarization dependence, sensitivity to channel interference, etc. (see other abstracts in this Annual Report). In the present abstract we focus on the feasibility of resonant soft X-ray emission to probe low energy excitations by means ofresonant electronic X-ray Raman scattenng....
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| 10. |
- Butorin, S. M., et al.
(author)
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Low-energy d-d excitations in MnO studied by resonant x-ray fluorescence spectroscopy
- 1996
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 54, s. 4405-4408
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Journal article (peer-reviewed)abstract
- We measured the Mn Lα,β x-ray fluorescence spectra of MnO excited by selected photon energies near the L2,3 absorption edges. The resulting resonant inelastic x-ray scattering spectra probe low-lying electronic excited states, due to dd and charge-transfer excitations. Using a two-step model and a purely atomic approximation, we reproduce both energies and varying intensities of dd excitations relative to the electronic recombination peak. Our results show that strongly varying line shapes in resonant x-ray emission need not be due to channel interference effects.
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