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Proceedings Paper

Gas-Phase Photoemission With Soft X-Rays: Cross Sections And Angular Distributions
Author(s): D A Shirley; P H Kobrin; C M Truesdale; D W Lindle; T A F errett; P A Heimann; U Becker; H G Kerkhoff; S H Southworth
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Paper Abstract

A summary is presented of typical gas-phase photoemission studies based on synchrotron radiation in the 50-5000 eV range, using beam lines at the Stanford Synchrotron Radiation Laboratory. Three topics are addressed: atomic inner-shell photoelectron cross sections and asymmetries, correlation peaks in rare gases, and core-level shape resonances in molecules. Photoelectron cross-section a(nZ) and asymmetry-parameter a(n0 studies in mercury vapor at photon energies up to 270 eV (up to 600 eV for a4f) extend coverage of these parameters to n<5 and 5<3. Comparison with Dirac-Slater and relativistic random-phase approximation calculations reveals systematic discrepancies. For example, distinct Cooper minima in a(n iZ,) are observed but not predicted, while predicted a(n9) values are typically too high. Correlation satellites have been studied for the K shells of helium (hv = 68-90 eV), neon (hv = 870-960 eV) and argon (hv = 3200-3320 eV). In helium the n=2 satellite peak was shown to have mainly 2p character at threshold, and its asymmetry was measured through the autoionizing resonance region. Tentative evidence was obtained that the neon satellites are less intense near threshold than in the high-energy limit, and that their intensities stay constant or decrease with increasing energy near threshold. A new satellite was observed in argon at 24.6 eV which appears to increase in intensity with energy. Molecular core-level shape resonances were observed for the first time by photoemission, yielding a(hv) and a(hv) for core levels from 180 eV binding energy (S 2p in SF6 and OCS) through C is in CO, CO2 and CF4, N ls in N2 and NO, and 0 is in CO and CO2 to 2490 eV (S ls in SF6). Several conclusions can be drawn about the photoelectron and Auger cross sections and asymmetry parameters.

Paper Details

Date Published: 27 March 1984
PDF: 8 pages
Proc. SPIE 0447, Science with Soft X-Rays, (27 March 1984); doi: 10.1117/12.939192
Show Author Affiliations
D A Shirley, University of California (United States)
P H Kobrin, University of California (United States)
C M Truesdale, University of California (United States)
D W Lindle, University of California (United States)
T A F errett, University of California (United States)
P A Heimann, University of California (United States)
U Becker, University of California (United States)
H G Kerkhoff, University of California (United States)
S H Southworth, University of California (United States)

Published in SPIE Proceedings Vol. 0447:
Science with Soft X-Rays
Roger W. Klaffky; F. J. Himpsel, Editor(s)

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