Spectral line shape variations in time-resolved photoemission from a solid

Laser assisted photoemission by a subfemtosecond ultraviolet pulse is studied by solving the time-dependent Schr?dinger equation for a one-dimensional model crystal. Without the laser field, the shape and the energy location of the spectrum are determined by the energy dependence of the photoemission cross section. In the presence of the laser field, the time growth of the population of the final state is predicted to cause extremely sharp variations of spectral width as a function of release time. This can help enhance time resolution of the measurements. A simple phenomenological model to describe the line shape is proposed.