Photoinduced ionization and dissociation of aniline-(methanol)n clusters

A linear tandem-type time-of-flight mass spectrometer was employed to study unimolecular dissociation of metastable aniline+-(methanol)n (An+-(CH3OH)n, n = 2–9) cluster cations formed by two-photon ionization of neutral clusters. The dominant dissociation channel was to liberate a single methanol molecule, namely, An+-(CH3OH)n → An+-(CH3OH)n−1 + CH3OH. The decay time constant of the ions ranged from 65 to 460 μs and turned out to be highly dependent on the cluster size. Also, hydrogen transfer mechanism in the formation of An+-(CH3OH)nH was examined by analyzing experimental results from isotopomers, such as deuterated An-d7+-(CH3OD) and An-d7+-(CD3OD) cluster ions. Density functional theory calculations were carried out to obtain optimized structures for neutral and ionic clusters and to support mechanisms related to the hydrogen transfer and unimolecular dissociation reaction.