Ultrafast spot-profile LEED of a charge-density wave phase transition

We investigate the optically driven phase transition between two charge-density wave (CDW) states at surface of tantalum disulfide (1 T-TaS 2 ). Specifically, we employ a recently improved ultrafast low-energy electron diffraction setup to study from nearly commensurate incommensurate (IC) CDW state. The experimental allows us follow transient changes in pattern with high momentum resolution and 1-ps pulse duration. In particular, trace intensities spot profiles crystal lattice, including main superstructure peaks, as well diffuse background. Harnessing enhanced data quality instrumental upgrade, laser-induced disorder system perform spot-profile analysis that yields substantial IC-peak broadening for very short time scales followed by prolonged narrowing.