Calculation of the X‐Ray Absorption Fine Structure in Shock‐Compressed Matter

Abstract

AbstractDense plasma modifications of X‐ray absorption fine structure (EXAFS) are investigated theoretically for shock‐compressed, strongly‐coupled plasma in the region of 1–5 times solid density and 1–20 eV temperature. The analysis includes explicit calculations (1) of the ion pair distribution functions to account for large amplitude thermal motion, (2) of the photoelectron scattering and phaseshift by solving the Schrödinger equation in the ion potential, and (3) of the photoelectron mean free path describing inelastic scattering on degenerate electrons of the plasma environment within Lindhard theory. Results are given for the K‐edge of aluminum. The fine structure survives for temperatures up to 20 eV, but only in a range of 50–100 eV above the edge. Position and amplitude of the first minimum may be used to extract information on plasma temperature and density, and a practical scaling relation is derived for future experiments.