Dynamic Stark effect and the Coulomb-Volkov approximation

A modified Coulomb-Volkov theory is used to study the interaction of intense laser pulses with atomic Hydrogen. Photon energy greater than the ionization potential and non-perturbative conditions are considered. The dynamical Stark effect is accounted by introducing the initial state coupling to the remaining discrete and continuum atomic spectrum. Both the Stark shift and the decay of the initial state are studied. The ionization spectra, the Stark shift and the total ionization probability are compared with results obtained from numerical solution of the time dependent Schroedinger equation. Both results agree well.