Molecular photodissociation with diverging couplings: An application toH2+in intense cw laser fields. I. The single-photon problem

The photodissociation of homonuclear ions exposed to continuous-wave (cw) lasers gives rise to asymptotically diverging couplings when approached in the electric-field gauge. Quantization of the laser-induced resonances becomes possible by complex rotation, leading to accurate energies, widths, and wave functions. A pseudoflux is endowed in the closed-channel component when calculated in the diabatic frame and for high laser intensities. A complex energy flux analysis performed in the adiabatic representation is developed, replacing the standard Siegert analysis which is no longer adequate for the extraction of the width from the asymptotic amplitude of the open-channel function. At the limit of strong radiative couplings the remaining nonadiabatic couplings asymptotically vanish. In the special case of constant potential couplings, the width is given by the asymptotic amplitude of the open-channel function through a modified Siegert analysis. Application is made to ${\mathrm{H}}_2^{+}$, in laser frequency and intensity regimes where a single-photon description is sufficient.