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O: Oberflächenphysik

O 26: Postersitzung (Rastersondentechniken, Nanostrukturen, Teilchen und Cluster, Methodisches, Oxide und Isolatoren, Grenzfl
äche fest-flüssig, Struktur und Dynamik reiner Oberfl
ächen, Oberfl
ächenreaktionen, Zeitaufg. Spektroskopie, Phasenüberg
änge

O 26.37: Poster

Mittwoch, 13. März 2002, 14:30–17:30, Bereich C

Non-Dipolar Effects in X-Ray Photoelectron Spectroscopy — •S. Sellner1,2, F. Schreiber1,2, A. C. Dürr1,2, H. Dosch1,2, I. A. Vartanyants2,3, B. C. C. Cowie4, and J. Zegenhagen41Institut für Theoretische und Angewandte Physik, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany — 2Max-Planck-Institut für Metallforschung, Heisenbergstr. 1, D-70569 Stuttgart, Germany — 3Department for Physics, University of Illinois, Urbana, IL 61801, USA — 4ESRF, B.P. 220, F-38043 Grenoble Cedex, France

X-ray photoelectron spectroscopy (XPS) is usually analyzed in the dipole approximation. This assumes that the X-ray wavelength, λ, is much larger than the radius, re, of the shell of the electron which is being excited. However, for high excitation energies and small binding energies, the condition λ ≫ re is not necessarily fulfilled. Using an X-ray standing wave (XSW) field as the source for excitation, we show how to determine both the magnitude and the phase of the lowest-order non-dipolar (quadrupole) contributions to the XPS cross-section. We find that these contributions can be significant and that they have to be included in a quantitative analysis in certain cases [1]. Specifically, we discuss the implications for the analysis of XSW data.

[1] F. Schreiber et al., Surf. Sci. Lett. 486 (2001) 519

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