Barrier suppression in high intensity photodissociation of diatomics: Electronic and permanent dipole moment effects

The infrared multiphoton photodissociation of a molecular ion, HCl+ in intense (I > 10(13) W/cm(2) >, short (tau less than or equal to 1 ps) laser pulses is studied numerically by solving the nonperturbative time-dependent Schrodinger equation for this system, In particular, since molecular ions have large permanent moments upon dissociation, the present calculation examines the relative importance of electronic and permanent dipole moments effects at high intensities. Both long (lambda = 20.6 mu) and short (lambda = 1.064 mu m) wavelength are compared to previous experiments and barrier suppression models. It is found in general that at long wavelength electronic effects predominate, thus justifying the use of a static field barrier suppression mechanism to predict the onset of dissociation. High intensity low frequency photodissociation also implies considerable redistribution of ponderomotive energies for light particles such as protons by charge transfer effects. (C) 1997 American Institute of Physics.