VIBRATIONAL AUTOIONIZATION IN POLYATOMIC-MOLECULES

A general framework for vibrational autoionization in polyatomic molec ules with nondegenerate ion cores is presented in terms of a nondiagon al quantum defect matrix. The expressions for the vibrational autoioni zation rate depend on two vibrational-mode-dependent factors; (1) a vi brational ''zero-point amplitude'' that describes the displacement alo ng a given normal coordinate and (2) a quantum defect derivative that describes the effect of the vibration on the electronic degrees of fre edom. The latter is closely related to the dipole moment derivative an d thus to the infrared intensity of that mode. This connection provide s insight into the recently observed mode dependence of the vibrationa l autoionization rates for NO2 and other small molecules. (C) 1997 Ame rican Institute of Physics.