Photoionization, fragmentation and proton transfer in 1-naphthol(NH_3)_n clusters

摘要

The fragmentation of photoionized 1-naphthol centre dot (NH_3)_n clusters is examined. In one-color resonant two-photon ionization experiments, fragmentation in the ion state is observed for every cluster size above n = 1. For small clusters (n <= 4), a single neutral ammonia is evaporated in the ion state. This ceases at energies 1500-2500 cm~(-1) above the ionization thresholds. Larger clusters, n >= 5, are readily ionized at much lower energies than n <= 4. They yield (1-naphthol centre dot (NH_3)_n_)~+, 1-naphthol centre dot (NH_3)_nH~+, and (NH_3)_nH~+ ion fragments. Several neutral ammonia molecules can be lost. These observations support predictions that n >= 5 clusters undergo proton transfer in the ground state.