Temperature dependence of EXAFS for bromide ions in solution

Abstract

Extended X-ray absorption fine structure (EXAFS) spectra have been obtained for bromide ions in water, 2,2,2-trifluoroethanol, ethylene glycol and n-butyl alcohol at various temperatures. Cumulant analysis was applied to the EXAFS data to determine the atomic distances of Br^–—O, the mean square relative displacements, σ², and the third-order cumulants, C₃. The potential-energy curves for the Br^–—O interaction were obtained from the analysis of σ²/T and C₃/T² by using the diatomic chain model with a first-principle calculation. A correlation was found between the anharmonicity in the Br^–—O interaction and the Mayer-Gutmann acceptor number of the solvent.