High Repetition Rate XUV Light with Differential-Gas-Jet for Time Resolved photoelectron spectroscopy

Abstract Time-resolved photoelectron spectroscopy is a powerful approach for probing transient surface morphology and ultrafast carrier dynamics in solids. Quantitative analysis of non-equilibrium dynamics requires stable light source with easy geometry and less space charging effect. Here we report a high-repetition-rate extreme-ultraviolet (XUV) pulses based on high-harmonic generation (HHG), designed to support state-of-the-art momentum microscopy (MM) for imaging ultrafast electron dynamics in both real and reciprocal space. The XUV source with an improved differential gas jet operates at 100 kHz repetition rate with central photon energy of 21.6 eV, spectral width of 110 meV, and the maximum photon flux of 3 × 10 10 photonsss (single-harmonic selection) delivered to the sample. The flux of single HHG is 1.5 times than that generated with a regular gas jet. Interferometry characterization of the gas density distribution in the differential gas jet reveals the influence of skimmer parameters on gas density profile, exerting a further notable influence on the HHG flux. By employing appropriate skimmers, the gas density can be capable of mitigating the decrease in gas density with increasing distance, enhancing the gas density at relatively far positions, and eventually enhance the harmonic flux. These results give important guiding significance for gas field manipulation in gas-distribution-sensitive light-matter interaction experiments.