Anionic and cationic photofragmentation of core-excited N₂O

We have measured all detectable cationic and anionic fragments in single-channel mode from N₂O as a function of photon energy in the vicinity of the nitrogen 1s core-level threshold. Due to the high degree of localization of the core electrons, the two excitations N_t1s → 3π^* and N_c1s → 3π^* show high levels of site-selective behaviour. The observed partial ion yield for the sole anionic fragment, O⁻, in conjunction with the partial cation yields, confirms our previous demonstration of anion-yield spectroscopy as a unique tool to identify core-level shape resonances.