Ultra-short X-ray sources generated through laser-matter interaction and their applications

This work is dedicated to the sources of ultra-short X-rays. The Kα source, the non-linear Thomson source, the betatron source and the X-γ source are presented. We show that a pump-probe experiment where the pump is a laser excitation and the probe is the X-Kα ultra-short radiation, can be used to study the dynamics of material structure with a time resolution of 100 femtosecond. We describe 2 applications that have been achieved in the field of solid physics by using the diffraction technique with a time resolution in the range of the femtosecond. The first application has permitted the observation and characterization of the ultra-quick solid-phase transition that occurs on the surface of a semiconductor crystal. The second experiment deals with the role of optical phonons in the antecedent processes that lead to such ultra-quick solid-phase transitions. (A.C.)