Vibrationally resolved electronic autoionization of core–hole resonances

We investigate the dynamics of molecular core–hole decay using dispersed fluorescence from an ionic valence–hole state in N₂. A core–hole excited state is created via the N₂(1s→1 π^*_g) transition, and this state electronically autoionizes to the N⁺₂(B ²Σ⁺_u) state. The vibrational branching ratios for the N⁺₂(B ²Σ⁺_u) state are then determined from N⁺₂(B ²Σ⁺_u→X ²Σ⁺_g) fluorescence. Fundamental aspects of core–hole state decay emerge clearly from these measurements. In particular, interference effects due to lifetime broadening of vibrational levels of the core–hole state can be investigated quantitatively using this method. As a result, dispersed fluorescence detection serves as a powerful tool for investigating R‐dependent aspects of molecular core–hole resonances. The experimental results do not agree with predictions based on previous theoretical developments, and possible causes for the discrepancy are discussed.