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

J. Phys. IV France 7 (1997) C2-539-C2-540
DOI: 10.1051/jp4/1997090

X-Ray Absorption Near Edge Spectroscopy (XANES) at the Phosphorus K-Edge of Triorganophosphineselenides

C. Engemann¹, J. Hormes², J. Clade³, M. Jansen³, C. Lauterbach⁴ and E. Hartmann<sup>4

1</sup>  Physikalisches Institut der Universität Bonn, Nussallee 12, 53115 Bonn, German
²  Physikalisches Institut der Universität Bonn, Nussallee 12, 53115 Bonn, Germany
³  Institut für Anorganische Chemie der Universität Bonn, Gerhard-Domagk-Strasse I, 53121 Bonn, Germany
⁴  Institut für Oberflächenmodifizierung, Permoserstrasse 15, 04318 Leipzig, Germany

Abstract
The usefulness of XANES measurements for analysing the local environment of the absorbing atom is demonstrated at the P K-edge for some triorganophosphineselenides. Using XANES as a fingerprint method, information about the influence of the first and higher coordination shells on the XANES spectra have been obtained. We demonstrate once again an influence of the electronegativity of the substituents bound to the absorbing atom on the spectra. Furthermore, we show that an aromatic substituent in the first coordination shell strongly influences the shape of the XANES resonances as compared to an aliphatic substituent. This is evident in a splitting of the white line, if the aromatic substituent is directly bound to the absorbing atom. In this case, the formation of a delocalized π-electron system is possible, which shortens the P-C_aryl bond length because of its positive mesomeric effect. These results are supported by MS Xα-calculations.

© EDP Sciences 1997