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Avviso di seminario
Giovedì 16 Giugno 2016 ore 11:00
Aula E terzo piano
Filippo Bencivenga
Non-linear experiments with free electron lasers
The advent of free electron laser (FEL) sources have permitted to develop advanced table-top methods, such as those based on non-linear optics, into the extreme ultraviolet (XUV) and x-ray domain. In this context we exploited the fully coherent XUV pulses delivered by the FERMI FEL facility to demonstrate a four-wave-mixing (FWM) response stimulated by XUV transient gratings (X-TG). More recently we used the unique two-colour seeded FEL emission available FERMI to carry out an XUV coherent Raman scattering (X-CRS) experiment. Both X-TG and X-CRS represent relevant stepping stones towards the development of more sophisticated FWM methods, which, so far, have been only theoretically conceived. In particular, the X-TG approach can be used for probing collective atomic dynamics in the mesoscopic (0.1-1 nm-1) wavevector range, which is of the highest relevance to understand the thermal and mechanical properties of disordered systems and nanostructures. On the other hand X-CRS can probe the ultrafast dynamics of high energy excitations, such as, e.g., valence band excitons, with the unique option of atomic-selectivity; the latter may turn into the capability to follow, in real-time, the dynamics of selected excitations among different and selectable atoms in a sample. Such FWM applications will be further developed at FERMI in user-dedicated experimental infrastructures.
studenti - dottorandi
Istituto Officina dei metalli

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