Photoelectron Velocity Map Imaging and Density-Functional Investigation of Bismuth and Lead Anions Solvated in Ammonia

We present the results of photoelectron velocity map imaging experiments for the photodetachment of small negatively charged Bi$_{n}$ and Pb$_{n}$ (n = 1-2) clusters solvated in ammonia using a Nd:YLF 527 nm laser. We report the vertical detachment energies of the observed multiple electronic bands and their respective anisotropy parameters derived from the photoelectron images. Density-functional theory calculations with generalized gradient approximation for the exchange-correlation potential were performed on these clusters to determine their molecular and electronic structures. Calculated ammonia binding energies and electronic charge transfers are used to rationalize the observed mass spectra distributions.