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 $2{\sigma }^{-1}2{\pi }^2({}^2\Delta ,{}^2\Sigma ^{\pm })$ resonances of ${\mathrm{N}}^{*}\mathrm{O}$ by a quantitative comparison between ab initio calculations and experiment.

• Received 29 January 2010

DOI:https://doi.org/10.1103/PhysRevLett.104.243001