Femtosecond phase Transitions with X-ray absorption Spectroscopy – FemTraXS

Femtosecond X-ray absorption spectroscopy is considered by many international groups as a major scientific objective because it provides crucial information on the dynamics of both electronic and atomic structures. However, there is still no source to perform routine experiments. This could change by using the Betatron x-ray source which also has the advantage of being laboratory sized (versus the very large research facilities such as x-ray free electron lasers).

We have recently demonstrated the remarkable potential of this source by carrying out the first femtosecond XANES experiment. We have measured the femtosecond dynamics of the L-edge of a solid copper sample brought up to dense and hot matter conditions (or WDM for Warm Dense Matter) by a femtosecond laser pulse.

Our long-term goal is to develop this new type of laboratory experiment, in fields as varied as physics, chemistry or biology, and in various environments ranging from condensed to diluted phases. Our strategy consists first of all in demonstrating the possibility of routine experiments in a regime where the electronic and atomic structures are strongly modified, which facilitates observation. In the three years of this project, we aim for unprecedented results on the ultra-fast dynamics of phase transitions up to the WDM regime in different prototype materials (noble metal, transition metal and covalent material) for which data have been long awaited by the community.

We have the will to disseminate this technique in other multidisciplinary fields of application, and we will use these results to convince future partners. We are convinced that in addition to the valuable data that we will obtain, this project will mark the emergence of the Betatron source and will pave the way to a new class of ultra-fast laboratory experiments.