Observation of completely destructive quantum interference between interacting resonances in molecular predissociation

A unique observation is presented of interacting predissociating resonances which exhibit completely destructive interference in a region between the resonances. The use of a double-resonance technique, in which single rotational levels of the b (1)Sigma (g) state of O-2 prepared by pumping the magnetic-dipole b <-- X transition, are probed by (2 + 1) resonance-enhanced multiphoton-ionization spectroscopy, eliminates overlapping rotational structure and enables observation of the interference process. Using a diabatic coupled-channel model, the interacting resonances are shown to be derived from the (1)(g) (v = 3, J = 17) Rydberg and II(1)Delta (g) (v = 6, J = 17) valence states.