Angular momentum distribution in Rydberg states excited by a strong laser pulse

We study the excitation to Rydberg states in the interaction of the hydrogen atom with a short, strong laser pulse. Utilizing solutions of the time-dependent Schrodinger equation we find that the parity of the populated angular momentum states agrees with the selection rules for multiphoton resonant absorption at low intensities, if the pulse length is not too short. In contrast, the parity effect cannot be observed for ultrashort pulses as well as for long pulses at high intensities. We further identify signatures of the population in the excited states via the line emissions from the populated np states after the end of the pulse exhibiting the parity effect.