A general formal theory is developed for the autoionization of molecules at energies within a few electron volts or less of threshold, specifically to include effects of the interaction of an excited Rydberg electron with the rotating, vibrating molecule—ion to which it is bound. The dominant coupling mechanism involves conversion of vibrational energy to electronic energy and is most efficient when the core can undergo a single quantum jump. A number of simplifications and approximations are discussed. Some of these are used in an application of the theory to the autoionization of H2. Autoionization rates are computed for a number of vibronic Rydberg states of this molecule, and are consistent with the available data. Model calculations for heteronuclear diatomics are presented to show how the presence of a vibrating dipole in the molecular core enhances the rates of autoionization, in comparison with the rates in homonuclear diatomics where vibrating quadrupoles stimulate the process. Several experiments are suggested, particularly the measurement of the angular distributions of electrons detached from heteronuclear diatomics.
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