Thermal disorder in Pt and Ir metal: Comparison of model and experimental extended x-ray-absorption fine structure

Abstract

Extended x-ray-absorption fine-structure (EXAFS) spectra were measured for Pt (bulk foil) and Ir (sintered supported catalyst) over the temperature range from 10 to 822 K and evaluated for the effects of thermal disorder on amplitude and phase. A procedure based on parallel analysis of experimental EXAFS spectra and model EXAFS spectra derived from an adjustable pair interaction potential is used to deduce structural and disorder parameters corrected for observed disorder-related effects present in conventional analysis methods. Comparison of results with a correlated Debye theory of the effect of disorder on EXAFS spectra shows close agreement.