Autoionisation of superexcited states in N2 to the N2+ B state

Vibrationally resolved N2+ (B–X) (1–2) and (0–1) emission bands were recorded after photoexcitation of N2 in the 20–46 eV energy range. The branching ratio between these transitions reveals strong non-Franck–Condon effects. Ab initio calculations using a configuration interaction method based on Kohn–Sham orbitals indicate that the autoionisation of certain superexcited states is responsible for some structures present in the branching ratio curve.