Molecular photodissociation with diverging couplings: An application toH2+in intense cw laser fields. II. The multiphoton problem

A nonperturbative time-independent method of calculating accurately partial widths of resonances formed in fragmentation processes is presented. It is based on a complex-energy probability-flux analysis performed in the adiabatic representation and turns out to be applicable whatever the strength or the spatial dependence of the interchannel couplings is. The method is applied to the photodissociation resonances of ${\mathrm{H}}_2^{+}$ exposed to an intense continuous-wave (cw) laser field. The photon channel pathways followed during the fragmentation are determined in terms of partial fluxes. Multiphoton absorption rates and branching ratios are extracted and compared with other recent studies. In the limit of weak laser intensities the formulas for the partial widths reduce to those resulting from the standard Siegert form for the open-channel components of the resonance wave functions.