Peculiarities of manifestation of the Rydberg resonance structure in multi-photon ionization of molecules

The structure of Rydberg resonances in ionization spectra of diatomic molec ules with regard for the joint effect of a weak (probing) field populating an intermediate (working) level and of an intense monochromatic linearly po larized radiation is studied. The major attention is paid to investigating the dependence of level widths Gamma on the strength of the intense field f and to exploring the possibility of manifestation of the stabilizing effec t (i.e. of narrowing the resonance curves with increasing intensity f). Pre viously this effect was discussed for model systems, hydrogen atom and atom s with a structureless core. It is demonstrated, by way of example of an H- 2 molecule, that, because of the nonadiabatic coupling with rotations, the field-induced resonance narrowing (in populating the two-component Rydberg R(0) branch) is possible when one of the two Rydberg series is excited. Whe n the two series are excited simultaneously, stabilization is possible only in narrow spectral regions where the stroboscopic effect (arising when the rotation periods of electrons and nuclei in some motion channels are match ed).