Ion-molecule chemistry within triply charged ammonia clusters

We present in this communication the first observation of "intramolecular" ion-molecule reactions within triply charged clusters produced via electron impact ionization of neat beams of ammonia molecules. The fragmentation pattern strongly suggests that reactions occurring within these triply charged clusters are similar to those previously observed for singly and doubly charged ammonia clusters. This behavior implies that these cluster ions consist of three singly charged ammonia cations which react separately within the bulk neutral cluster. That is, either one, two, three, or none of the ammonia cations may react with the solvating neutrals within the cluster. We also report for singly charged ammonia clusters the observation that extensive fragmentation can occur within the cluster producing ions with the empirical formulas of (NH₃)_n-1N⁺ and (NH₃)_n-1NH⁺.