X-Ray Absorption Spectroscopy Applied to Pressure-Induced Transformations of Semiconductors

X-ray absorption spectroscopy (XAS) provides information on the local environment of a given atom species and therefore is very sensitive to pressure-induced transformation, in particular when coordination changes occur. This technique allows to determine with a good accuracy the onset of phase transformations. Combined with X-ray diffraction, XAS allows to follow the evolution of the structural parameters under high pressure. The low energy part of the spectrum, related to the symmetry around the absorbing atom, is a fingerprint of the structure and can be compared to simulated spectra using multiple scattering calculations. For amorphous samples X-ray absorption spectroscopy remains a very efficient tool to study the local order in the sample. XAS at high pressure and high temperature using large volume cells is now available. Preliminary results on melting of Ge and CdTe are presented.