Predissociation-induced rovibrational autoionization and zero-energy photoelectrons

Abstract

A recent model of molecular autoionization involves an intermediate neutral dissociative state to explain extensive vibrational structure in the photoelectron spectrum. As an extension of this previous work, we propose a modification of the model by invoking a continuity condition in order to explain the ‘‘zero-energy’’ electron phenomenon. The condition requires that any photoelectron spectrum extending smoothly to zero energy with finite probability must involve the excitation not only of the continuum, but also of high Rydberg states. Rotational autoionization of these states will produce a very narrow photoelectron peak at zero energy superimposed on a broader peak due to vibrational autoionization.