Channel-mixing effects on dissociative recombination

Configuration interaction has been known to cause resonance structures in atomic photoionization spectra and electron-scattering cross sections since 1961 [U. Fano, Phys. Rat. 124, 1866 (1961)]. Generalized in terms of channel mixing and expressed in the framework of multichannel quantum defect theory, it applies also to molecular spectra and dissociative processes, in particular to dissociative recombination. We show here that besides causing resonances, channel mixing can in some cases make the dissociative recombination process possible, while at first view it should not happen due to the absence of direct coupling between the entrance channel (electronic continuum) and the exit channel (nuclear continuum).