Fragmentation ofH2+in strong 800-nm laser pulses: Initial-vibrational-state dependence

Abstract

The fragmentation of the ${\mathrm{H}}_{2}^{+}$ molecular ion in 25-fs, 800-nm laser pulses in the intensity range 0.05--0.5 P ${\mathrm{W}/\mathrm{c}\mathrm{m}}^{2}$ is investigated by means of wave-packet propagation calculations. We use a collinear reduced-dimensionality model that represents both the nuclear and electronic motion by one degree of freedom including non-Born-Oppenheimer couplings. In order to reproduce accurately the properties of the ``real'' three-dimensional molecule, we introduce a modified ``soft-core'' Coulomb potential with a softening function that depends on the internuclear distance. The analysis of the calculated flux of the outgoing wave packets allows us to obtain fragmentation probabilities and kinetic-energy spectra. Our results show that the relative probabilities for dissociation and Coulomb explosion depend critically on the initial vibrational state of the molecular ion.