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 N₂⁺ (B ²Σ_u⁺) state. The vibrational branching ratios for the N₂⁺ (B ²Σ_u⁺) state are then determined from N₂⁺ (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.