Selective vibrational excitation in the resonant Auger decay following core-to-π^* transitions in N₂O

In N₂O a detailed study of the vibrational distribution of the X̃ state reached after decay of core-to-π^* excitation of N terminal, N central and O 1s core levels is reported. We observe a change in the relative intensity of bending versus stretching modes while scanning the photon energy across all three resonances. While this effect is known to be due to the Renner-Teller splitting in the core-excited states, we could derive that the antisymmetric stretching is excited mainly in the decay of the N terminal 1s-to-π^* excitation. An explanation for such selectivity is provided in terms of interplay of vibrational structure on potential energy surfaces of different electronic states involved in the process.