Anharmonic Contributions to High-Temperature EXAFS Spectra: Theory and Comparison with Experiment

This is the authors' abstract. We don't add key points for this paper.

In this work the anharmonic contributions to the high-temperature EXAFS spectra have been evaluated by considering the anharmonic contributions to the thermal vibrations of atoms and using the single-shell model. The anharmonicity calculated by our new formula is proportional to the temperature and inversely proportional to the distance between the absorbing atom and its neighbour located in a spherical shell which can be considered as the outer shell in the case of particles. The measured EXAFS spectra of Cu at several temperatures have been presented providing its strucuctural informations, among them the atom position of the first shell is different from the one calculated by the harmonic model by 0.05 Å at 700 K and 0.01 Å at 295 K. These measured results agree very well with the ones calculated by present anharimonic theory. This creates a good possibility for extraction of physical parameters from experiment by using our procedure.