Observation of Magic Numbers in the Population Distribution of the (NH3)(n-1) NH2(+) and (NH3)(n)H2(+) Cluster Ions: Implications for Cluster Ion Structure

摘要

We present the relative yields of the cluster ions, (NH3)(n-1)NH2(+) and (NH3)nH2(+), produced by electron impact ionization of a supersonic molecular beam of neutral ammonia clusters, as functions of cluster ion size, neutral beam stagnation temperature, and electron impact energy. Our observation as a magic number at n=7 in the distribution of (NHs)(n)-1NH2(+) clusters ions is interpreted in terms of an intracluster bimolecular association reaction between a nascent NH2(+) daughter ion and an adjacent NH3 solvent molecule, giving rise to a protonated hydrazine product ion. Our observation of magic numbers at n = 5 and n = 8 in the (NH3)NH2(+) cluster ion distribution is consistent with the production of the N2H8(+) Rydberg radical cation via an intracluster ion molecule reaction. The dependence of the yields of these solvated Rydberg radical cations on the stagnation temperature of the neutral molecular beam supports the notion that extensive solvation destabilizes these cluster ions. Amines, Hydrogen, Clusters. (mjm)