Attosecond impulsive stimulated X-ray Raman scattering in liquid water.

Alexander, Oliver; Egun, Felix; Rego, Laura; Gutierrez, Ana Martinez; Garratt, Douglas; Cárdenas, Gustavo Adolfo; Nogueira, Juan J; Lee, Jacob P et al. · Sci Adv · 2024

basic_science · Level V

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Abstract

We report the measurement of impulsive stimulated x-ray Raman scattering in neutral liquid water. An attosecond pulse drives the excitations of an electronic wavepacket in water molecules. The process comprises two steps: a transition to core-excited states near the oxygen atoms accompanied by transition to valence-excited states. Thus, the wavepacket is impulsively created at a specific atomic site within a few hundred attoseconds through a nonlinear interaction between the water and the x-ray pulse. We observe this nonlinear signature in an intensity-dependent Stokes Raman sideband at 526 eV. Our measurements are supported by our state-of-the-art calculations based on the polarization response of water dimers in bulk solvation and propagation of attosecond x-ray pulses at liquid density.