Proceedings of the 9th International Conference on X-Ray Absorption Fine Structure

J. Phys. IV France 7 (1997) C2-195-C2-197
DOI: 10.1051/jp4/1997161

Exact Atomic Absorption Background for Rb K-Edge EXAFS

A. Kodre¹, I. Arčon² and R. Frahm<sup>3

1</sup>  Jožef Stefan Institute, Jamova 39, P.P. 3000, 1001 Ljubljana, Slovenia, and Dept. of Physics, University cf Ljubljana, Slovenia
²  Jo[MATH]ef Stefan Institute, Jamova 39, P.P. 3000, 1001 Ljubljana, Slovenia, and Dept. of Physics, University cf Ljubljana Slovenia
³  Hamburger Synchrotronstrahlungslabor, DESY, Notkestrasse 85, 22603 Hamburg, Germany

Abstract
The atomic absorption background can directly be determined only for very few elements. In one instance the absorption of Rb vapor above K-edge is measured: the spectrum approximates to a very high degree the atomic background for EXAFS of Rb⁺ ion in aqueous solution of RbNO₃. It includes several sharp multielectron excitation features - resonances and absorption edges - which are poorly described by the usual polynomial or spline ansatz. Using it as a starting background approximation for the ion EXAFS, the harmonic components are reliably reconstructed: removing them from the original ion absorption spectrum, the exact Rb⁺ atomic background is recovered. It differs from the vapor absorption spectrum only in the [1s3d] region where an additional resonance appears as a replica of the "white line" at the Rb⁺ K edge. The recovered shape of the exact atomic background can be extended by parametrisation to the neighbor elements.

© EDP Sciences 1997