J. Phys. IV France 7 (1997) C2-195-C2-197
Exact Atomic Absorption Background for Rb K-Edge EXAFSA. Kodre1, I. Arčon2 and R. Frahm3
1 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
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