Photoionization, fragmentation and proton transfer in 1-natphthol(NH3)n clusters

The fragmentation of photoionized 1-naphthol.(NH3)(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 less than or equal to 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 greater than or equal to 5, are readily ionized at much lower energies than n less than or equal to 4. They yield(1-naphthol.(NH3)(n))(+), 1-naphthol.(NH3)(n)H+, Md(NH3)(n)H+ ion fragments. Several neutral ammonia molecules can be lost. These observations support predictions that n greater than or equal to 5 clusters undergo proton transfer in the ground state. (C) 1999 Elsevier Science B.V. All rights reserved.