Renormalized Coulomb-Volkov approach to strong ionization by femtosecond laser pulses

Recent theoretical approaches to the ionization of atoms by short laser pulses, based on Coulomb-Volkov (CV) wavefunctions, appear very successful in predicting electron spectra when perturbation conditions prevail. Extending CV treatments to non-perturbative conditions requires, at least, to take into account the depletion of the initial state during the interaction. To do it, one proposes here an easy-to-implement procedure that is restricted to the case of photon energies greater than the ionization potential. This procedure is then introduced in a previous CV treatment thus giving rise to a renormalized Coulomb-Volkov (RCV) approach. RCV predictions of electron spectra are compared to those of a full numerical treatment in a case where ionization is almost saturated. A very good agreement is found