Time-dependent dynamics and population transfer during intense laser pulses

During an intense, short laser pulse an electron may remain in its ground state, be transferred to an excited state, or ionize with a particular energy. We have integrated the time-dependent Schrodinger equation for various laser intensities, pulse lengths and atomic systems to examine the interplay between these possibilities. At intensities, the results point to at least two circumstances in which some fraction of the electrons a pulse may remain in excited states after the pulse has passed: rapid passage through a multiphoton resonance or a multiphoton open-quotes channel closingclose quotes due to the ponderomotive shift of the ionization limit. Both of these processes show complicated dependencies on the pulse duration. At higher intensity (the tunneling limit) the dynamics are dominated by the essentially classical motion of the electron after it has reached the continuum, as evidenced by the high harmonic cutoff