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- Hedin, Lars
(author)
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Optical potentials and damped one-electron functions in photoemission and electron scattering
- 1990
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In: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 51, s. 91-102
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Journal article (peer-reviewed)abstract
- Recently a new approach to photoemission, EXAFS and electron scattering has been developed. The correlations between target electrons are separated from the active electron-target electron correlations, and the damping effects are coming out explicitly. The theory uses van Hove diagonal Green's functions and projection operator techniques, not the usual diagram expansions. By omitting from the start terms in the Hamiltonian which lead to reabsorption of the active electron (photoelectron or scattered electron), remarkably simple expressions are obtained. These expressions contain optical potentials which damp the electron propagation, and “fluctuation potentials” which determine the inelastic scattering. The fluctuation potentials also appear in the expressions for the optical potentials. On the RPA level of approximation the fluctuation potentials are obtained from the dielectric response function of the target. The theory is quite general, but its main advantages are for extended systems, where the damped propagators and damped one electron functions are important effects. The present theory should make it possible to quantitatively attack a number of correlation effects in different spectroscopies.
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| 2. |
- CHAKAROV, DV, et al.
(author)
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INTERACTION OF WATER WITH POTASSIUM ON GRAPHITE - A HREELS STUDY
- 1993
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In: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 64-5, s. 279-285
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Journal article (peer-reviewed)abstract
- Water and coadsorbed water + potassium on the basal plane of graphite were studied with high resolution electron energy loss spectroscopy (HREELS) at 85 K and after stepwise annealing up to 500 K. Water adsorbs non-dissociatively on both clean and potassium precovered surface at 85 K. The vibration spectra, together with thermal desorption spectroscopy (TDS) reveal a series of reactions within the coadsorbed layer leading to the formation of KOH, KH, and KOx and volatile products. Eventually a precursor to CO2 formation, of yet unindentified composition and observed also in K + O-2 coadsorption studies on graphite, is observed at approximate to 27 meV.
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| 3. |
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| 4. |
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| 5. |
- Antonsson, H, et al.
(author)
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VIBRATIONAL MOTION AND GEOMETRICAL STRUCTURE IN ADSORBED CO STUDIED BY CORE LEVEL PHOTOELECTRON-SPECTROSCOPY
- 1990
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In: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 54, s. 601-613
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Journal article (peer-reviewed)abstract
- High resolution core level spectra from CO adsorbed on clean and hydrogen precovered Ni(100) and CO adsorbed on Cu(100) are presented. The core level binding energy is shown to be sensitive to the adsorption site. Cluster calculations reproduce the general trend of the binding energy shifts between the on top and hollow sites of CO/Ni(100). In the coadsorption system CO/H/Ni(100) three different adsorption sites have been observed with a maximum binding energy shift of 2.6 eV for the Ols level. The temperature dependence of the Cls and Ols line profiles in CO/Ni(100) has been carefully investigated. The temperature dependent broadening is due to thermal excitations of frustrated translations parallel to the surface. The spectra from CO on Cu(100) show no temperature dependence below 200K.
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