Preparation and probing of coherent vibrational wave packets in the ground electronic state of HD^{+}

We have investigated the formation of coherent vibrational wave packets in the ground electronic state of HD+ on exposure to intense ultrashort laser pulses of wavelength 1060 nm. The effects of the duration and field strength of the pulse on the final composition of the residual bound nuclear wave packet generated by such impulsive excitations have been studied. The resulting wave packet is allowed to evolve freely on the potential surface for some time, after which a weak pulse of sufficiently large duration is used for probing its composition. This pulse can cause only single-photon dissociation. The simulations have been performed with different probe wavelengths for accessing information about different portions of the wave packet in the vibrational quantum number space. Our aim was to investigate the extent to which information obtained from the kinetic-energy spectra of the photofragments induced by the probe pulse can be correlated to the structure of the wave packet. Simple time-dependent perturbation calculations have also been performed for obtaining the relative strengths of photofragment signals arising from different vibrational levels due to wave-packet dissociation. A comparison with our numerical results indicates that though the general features of the photofragment kinetic-energy spectra from a wave packet are consistent with the perturbation theory results in the intensity regime studied, dynamical evolution during a long pulse can modify the relative heights of the kinetic-energy peaks through nonperturbative interactions in some cases.