Actions for Fourier transform photoelectron diffraction and its application to molecular orbitals and surface structure [electronic resource].

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Fourier transform photoelectron diffraction and its application to molecular orbitals and surface structure [electronic resource].

Published
Washington, D.C. : United States. Dept. of Energy, 1998.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description
123 pages : digital, PDF file
Additional Creators
Lawrence Berkeley National Laboratory, United States. Department of Energy, Pennsylvania State University, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
Photoemission intensities from the molecular orbitals of c(2x2)CO/Pt(111) over a wide photon energy range were measured and analyzed by the same methods developed for structural studies using core levels. The 4σ orbital center of gravity is found to be concentrated between the C and O atoms, while that of the 5σ orbital lies between the C atom and the Pt surface. The C 1s photoelectron diffraction was used to determine the adsorption geometry. The earlier ambiguity that multiple scattering is needed to correctly model a χ curve while single scattering is sufficient for understanding major peaks in the ARPEFS-FTS is clarified by studying the clean Ni(111) surface. In the normal emission case, several different combinations of scattering events have similar path length differences (PLDs), and can either cancel each other or enhance the corresponding FT peak. In the off-normal case the degeneracy is greatly reduced due to the lower degree of symmetry. In normal emission AR PEFS, up to third order multiple scattering is needed to describe fully both the χ curve and its FT spectrum. To improve the spectral resolution in the ARPEFS-FT analysis, several new spectral analysis methods are introduced. With both autocorrelation autoregression (ACAR) and autocorrelation eigenvector (ACE), we can produce a reliable power spectrum by following the order-closing procedure. The best spectra are usually obtained when the autocorrelation sequence is computed with lags up to half the data range. A simple way of determining surface adsorption sites is proposed as follows: First use a single scattering cluster for possible adsorption sites to construct the geometrical PLDs from the strong backscattering events; then compare these PLDs with those obtained from the ARPEFS-FT analysis of the experimental data. After the preferred adsorption site is determined, fine tune the interlayer distances according to the positional R-factor.
Report Numbers
E 1.99:lbnl--42589
lbnl--42589
Subject(s)
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Dissertation Note
Thesis (Ph.D.); Supercedes report DE00006458; Submitted to the Pennsylvania State Univ., Dept. of Physics, University Park, PA (US); PBD: 30 Nov 1998; PBD: 30 Nov 1998
Note
Published through SciTech Connect.
11/30/1998.
"lbnl--42589"
Zhou, Xin.
Funding Information
AC03-76SF00098
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