X-Ray Absorption at High Pressure

Abstract

Initial measurements are reported on the extended x-ray-absorption fine structure (EXAFS) of the Fe $K$ edge in Fe${\mathrm{S}}_{2}$ to 64 kbar and Fe${\mathrm{F}}_{2}$ to 21 kbar. With this new technique the Fe-Fe spacings are directly observed to vary in accordance with high-pressure x-ray diffraction measurements of the corresponding lattice parameters. In contrast, the Fe-S spacing in pyrite is found to be much less compressible. Pressure reduction of the mean-square deviations in the iron-ligand bond lengths are also given.