Microscopic Solvation Process of Alkali Atoms in Finite Clusters: Photoelectron and Photoionization Studies of M(NH3)n and M(H2O)n (M = Li, Li-, Na-)

Abstract

Photoelectron spectra (PESs) of Li-(NH3)n (n ≤ 16), Na-(NH3)n (n ≤ 12), and Na-(H2O)n (n ≤ 7), as well as the ionization potentials (IPs) of Li(NH3)n (n ≤ 28) and Li(H2O)n (n ≤ 46), are examined. PESs of Li-(NH3)n (n ≤ 10) exhibit three bands derived from the Li(32S)−Li-(1S), Li(22P)−Li-(1S), and Li(22S)−Li-(1S) transitions. The vertical detachment energies of the 32S- and 22P-type states decrease dramatically with increasing n. For n ≥ 11, the transitions to the 22P- and 32S-type states almost become degenerate with the transition of the neutral ground (22S) state. In addition to these observations, we also find the red shift of the 22S-type transition with a much slower rate. The similar spectral trends are also observed for the Na(32P)−Na-(1S) and Na(32S)−Na-(1S) transitions of Na-(NH3)n. On the other hand, the transitions of Na-(H2O)n exhibit the opposite shifts, and the 2P−2S energy separation does not change. As for Li(H2O)n, we find a monotonous decrease in IPs with n ≤ 4 and a constant IP behavior...