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 ¹Σ⁺_g state of O₂, 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 d ¹Π_g\(v = 3,J = 17\) Rydberg and II ¹Δ_g\(v = 6,J = 17\) valence states.