Interaction of a model atom exposed to strong laser pulses: Role of the Coulomb potential

With the help of the solution of the time-dependent Schrodinger equation in momentum space, we study the above-threshold ionization spectrum resulting from the interaction of atomic hydrogen with an infrared and XUV short laser pulses. Our calculations are based on a model where the kernel of the nonlocal Coulomb potential is replaced by a finite sum of N symmetric separable potentials, each of them supporting one bound state of atomic hydrogen. Here, we consider only the case of 1s, 2s, and 2p states. Thus, the theory fully accounting for the important 1s-2p transition, explains the photoelectron spectrum as well as the total ionization probability for the resonant case. We compared the results given by our theory with the numerical solutions of the time-dependent Schrodinger equation. © 2013 American Physical Society.