Speaker
Description
Coherent nonlinear light–matter interaction with X-rays gives access to a regime in ultrafast spectroscopy in which atomic resolution meets femtosecond and attosecond timescales. Particularly X-ray four-wave mixing, involving several resonant transitions in a single coherent nonlinear process, has the potential to provide information on the electronic states coupling, coherent electron motion,correlation and dynamics, with state and site selectivity.
We demonstrate coherent four-photon interactions with core-shell electrons using broadband SASE X-ray pulses from a free-electron laser. A square spatial mask splits the incoming beam into three cut out beams arranged in a ‘folded BOX’ geometry, enabling background free signal detection.
The all-X-ray four-wave mixing signals, measured in gaseous neon, arise from doubly resonant nonlinear processes involving Raman transitions. The 2D spectral maps (photon-in/photon-out) represent a step towards multidimensional correlation spectroscopy at the atomic scale.
Funding Agency
Swiss National Science Foundation - grant no. 200021-165550/1, R’Equip grant no. 206021-182988 European Union Horizon 2020 program - Marie Skłodowska-Curie grant 884104 (PSI-FELLOW-III-3i).
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