Symmetry-Forbidden Electronic State Interference Observed in Angularly Resolved NO+(A1Π) Deexcitation Spectra of the N*O(2σ-12π2) Resonance

Quantum mechanical interference between different pathways in inner-shell resonance excitation-deexcitation spectra is a realization of a double-slit experiment on the atomic scale. If the intermediate inner-shell resonances are of different symmetries, this interference is symmetry forbidden in the solid-angle-averaged or magic-angle-recorded deexcitation spectra. It has, however, been suggested that interference may by observable in off-magic-angle-recorded spectra. Here, we prove this interference in angularly resolved deexcitation spectra of the 2 sigma(-1)2 pi(2)((2)Delta, (2)Sigma(+/-)) resonances of N*O by a quantitative comparison between ab initio calculations and experiment.