Attosecond impulsive stimulated X-ray Raman scattering in liquid water

Area of Science:

• * Physical Chemistry
• * Atomic and Molecular Physics
• * Femtochemistry

Background:

• * Understanding the ultrafast dynamics of water is crucial due to its ubiquitous role in chemical and biological processes.
• * X-ray Raman scattering is a powerful technique for probing electronic structure, but its application to liquids with ultrafast time resolution is challenging.

Purpose of the Study:

• * To measure impulsive stimulated x-ray Raman scattering in neutral liquid water.
• * To investigate the ultrafast excitation of electronic wavepackets in water molecules using attosecond pulses.
• * To identify and characterize nonlinear optical signatures associated with these excitations.

Main Methods:

• * Utilized attosecond X-ray pulses to impulsively excite electronic wavepackets in water molecules.
• * Measured the resulting X-ray Raman scattering spectra, specifically looking for nonlinear signatures.
• * Performed state-of-the-art calculations on water dimers in bulk solvation and X-ray pulse propagation.

Main Results:

• * Successfully measured impulsive stimulated x-ray Raman scattering in liquid water.
• * Observed an intensity-dependent Stokes Raman sideband at 526 eV, indicating a nonlinear process.
• * Confirmed the creation of an electronic wavepacket at a specific atomic site within hundreds of attoseconds.

Conclusions:

• * Impulsive stimulated x-ray Raman scattering is a viable technique for probing ultrafast electronic dynamics in liquids.
• * The observed nonlinear signature provides direct evidence of attosecond wavepacket creation in water.
• * The findings advance our understanding of light-matter interactions at the attosecond timescale in condensed phases.