Space and surface-state effects in multiphoton emission

We investigate multiphoton emission of electrons from solid surfaces in the presence of nonperturbative monochromatic laser fields. We study the dependence of transmission probabilities on surface states, the penetration depth of laser fields in solids and the size of the laser focus in vacuum. To this end we present a one-space-dimensional model which permits to study these problems and develop a numerically stable algorithm for solving the corresponding time-dependent Schrödinger equation.