Multiphoton Ionization of Ammonia Clusters and the Dissociation Dynamics of Protonated Cluster Ions
Ammonia clusters, produced via supersonic expansion, are subjected to multiphoton ionization using a tunable pulsed laser. The products of ionization and subsequent dissociation processes are investigated using a time‐of‐flight mass spectrometer equipped with a reflectron (reflecting electric field). Cluster ions containing more than 65 ammonia molecules were formed via internal ion molecule reactions taking place within the initially ionized aggregate. The proton transfer reaction which ensues leads to substantial excess internal energy and subsequent cluster decomposition. Dissociation due to both collisional and unimolecular processes was identified in the field‐free region. Studies of the dynamics of dissociation were made for species up to the protonated 16‐mer; the loss of up to at least five monomer units following cluster ion formation was observed. Results of an investigation of the influence of laser fluence and the energy of the ionizing photons are also presented. REFERENCES
The Journal of Chemical Physics
Digital Object Identifier (DOI)
O. Echt, P. D. Dao, S. Morgan and A. W. Castleman, Jr., Multiphoton Ionization of Ammonia Clusters and the Dissociation Dynamics of Protonated Cluster Ions, J. Chem. Phys. 82 (1985) 4076, DOI: 10.1063/1.448849.