Solvent resonance effect on the anisotropy of N O- (N2 O)n cluster anion photodetachment

Photodetachment from N O- (N2 O)n cluster anions (n≤7) is investigated using photoelectron imaging at 786, 532, and 355 nm. Compared to unsolvated N O-, the photoelectron anisotropy with respect to the laser polarization direction diminishes drastically in the presence of the N2 O solvent, especially in the 355 nm data. In contrast, a less significant anisotropy loss is observed for N O- (H2 O)n. The effect is attributed to photoelectron scattering on the solvent, which in the N2 O case is mediated by the Π2 anionic resonance. No anionic resonances exist for H2 O in the applicable photoelectron energy range, in line with the observed difference between the photoelectron images obtained with the two solvents. The momentum-transfer cross section, rather than the total scattering cross section, is argued to be an appropriate physical parameter predicting the solvent effects on the photoelectron angular distributions in these cluster anions.