Numéro
J. Phys. IV France
Volume 7, Numéro C2, Avril 1997
Proceedings of the 9th International Conference on X-Ray Absorption Fine Structure
Page(s) C2-137 - C2-140
DOI https://doi.org/10.1051/jp4/1997133
Proceedings of the 9th International Conference on X-Ray Absorption Fine Structure

J. Phys. IV France 7 (1997) C2-137-C2-140

DOI: 10.1051/jp4/1997133

XAFS and Thermal Averaging

E.A. Stern

Department of Physics, Box 351560, University of Washington, Seattle, WA 98195, U.S.A.


Abstract
XAFS measures ρ(r), the distribution of the magnitude r of the relative vector displacement f between a center probe atom and its neighbors. The related ρ(r) of the distribution of the vector distance between the probe atom and its neighbors defines a pair potential V(r) which is thermally averaged over the position of all of the other atoms in the material being investigated. It is shown that there are subtle differences between ρ(r) and p(r) which lead to a new correction term to XAFS measurements necessary to obtain the correct thermal expansion of interatomic distances. Besides measuring ρ(r), XAFS allows the determination of both ρ(r) and V(r) which include σ2 addition to the usual σ2x, the mean squared vibrational disorder perpendicular and along the line between the average position of the pair of atoms, respectively.



© EDP Sciences 1997