Résumé
We propose here to perform a pump and probe X-ray diffraction experiment to study the structural changes induced by laser illumination. Chalcogenide glasses show numerous interesting, and often puzzling, effects when irradiated with a laser (i.e., refractive index and density variations). Although the phenomenology of these effects has been studied and discussed, their microscopic origin is still debated. The majority of the proposed models postulates that the impinging photons trigger atomic rearrangement, but there are not detailed structural studies. With the proposed experiment we aim at understanding the structural variations caused by the photons and their role on the photoinduced phenomena.