Solvation effects on angular distributions in H^-(NH ₃)_n and NH₂^-(NH₃) _n photodetachment: Role of solute electronic structure

We report 355 and 532 nm photoelectron imaging results for H ^-(NH₃)_n and NH₂^-(NH ₃)_n, n=0-5. The photoelectron spectra are consistent with the electrostatic picture of a charged solute (H^- or NH ₂^-) solvated by n ammonia molecules. For a given number of solvent molecules, the NH₂^- core anion is stabilized more strongly than H^-, yet the photoelectron angular distributions for solvated H^- deviate more strongly from the unsolvated limit than those for solvated NH₂^-. Hence, we conclude that solvation effects on photoelectron angular distributions are dependent on the electronic structure of the anion, i.e., the type of the initial orbital of the photodetached electron, rather than merely the strength of solvation interactions. We also find evidence of photofragmentation and autodetachment of NH₂^-(NH₃)_2-5, as well as autodetachment of H^-(NH₃)₅, upon 532 nm excitation of these species.