Description
The recent advent of Free Electron Lasers (FELs) has enabled the extension of experimental techniques traditionally developed for tabletop pulsed lasers into much shorter wavelength regimes. This breakthrough opens new opportunities for probing ultrafast dynamical processes with unprecedented spatial and temporal resolution. Among the expanding range of FEL-based methodologies, nonlinear spectroscopies in the vacuum ultraviolet to soft X-ray energy range are particularly promising. Pioneering transient grating experiments performed at the FERMI FEL have demonstrated that four-wave mixing (FWM) optical techniques can now be successfully implemented at nanometer wavelengths. Given the wide variety of possible FWM schemes, numerous unexplored opportunities remain. In this contribution, we will discuss promising new directions for FWM experiments based on FEL sources.
