Probing doubly excited ionic states of [Formula Presented] via a triple excitation above the N [Formula Presented] threshold in the [Formula Presented] molecule

Angle-resolved resonant Auger-electron spectroscopy has been carried out on the nitrogen molecule at selected photon energies around 419 eV, where a [Formula Presented] core electron and two valence electrons are promoted into the lowest unoccupied molecular orbital [Formula Presented] Significant enhancement of a specific band, which cannot be disentangled in direct photoionization, is observed at a binding energy of 37.6 eV, with a value of the anisotropy parameter [Formula Presented] much smaller than 2. We assign this new band to the transition to a doubly excited cationic state of [Formula Presented] in which two of the excited valence electrons remain in the [Formula Presented] orbital, proposing a “double spectator” type decay mechanism. This observation shows how to preferentially probe multiply excited configurations of cations using multiple resonant excitation.