INFLUENCE OF SOLVATION ON DISSOCIATION - METASTABLE UNIMOLECULAR DECOMPOSITION OF MIXED AMMONIA ACETONE CLUSTER IONS

Metastable unimolecular decomposition processes of the mixed ammonia-acetone cluster ions are studied using a reflectron time-of-flight mass spectrometer in conjunction with multiphoton ionization. In a time window of a few tens of microseconds, the [(NH3)n·(C3H6O)m]H+, n=1, m=2-5 ions lose one acetone moiety whereas the [(NH3)n·(C3H6O)m]H+, n=2-18, m=1-5 ions lose one ammonia moiety via unimolecular decomposition. The unimolecular decomposition processes are found to be independent of the formation method of the mixed neutral clusters in this study, indicating that the rearrangement process following ion production and the ensuing ion-molecule reactions is rapid compared to the times of observation. The present results show that the cluster ions have a central core corresponding to NH4 +, to which the other ligands making up the cluster are bound. © 1990.