high-resolution x-ray stimulated Raman spectroscopy using stochastic pulses

The X-ray free-electron lasers (XFELs) generate high-intensity x-ray pulses, which enable x-ray nonlinear spectroscopies. The extension of nonlinear spectroscopies to the x-ray domain promises the observation of electronic dynamics in their natural timescale with atomic spatial resolution. Stimulated x-ray Raman spectroscopy is an especially powerful tool, which works in a propagation mode and combines large signal enhancement through stimulated emission with ultrahigh energy resolution that overcomes the core-hole lifetime broadening. We present high-resolution stimulated Raman spectroscopy realized using stochastic XFEL pulses and correlation techniques. A covariance map between the transmitted incident SASE pulse and the stimulated Raman scattering produces a high-resolution x-ray Raman spectrum. This promising tool could be applied to study ultrafast electronic and molecular dynamics such as charge transfer in complex systems.