Intracluster ion-molecule reactions within the photoionized van der Waals complexes of C₆H₅F with NH₃ and with H₂O

Intracluster ion-molecule reactions of the photoionized van der Waals complexes of C₆H₅F with NH₃ and with H₂O have been investigated by means of two-color multiphoton ionization spectroscopy in combination with mass analysis. Two different intracluster reactions of C₆H₅F-NH₃, the substitution reaction yielding C₆H₅NH₂⁺ and the dissociation yielding C₆H₅F⁺, were induced by the selective photoionization of different isomers of the complexes. Ionization threshold spectra of the complexes and appearance energies of the reaction products were observed. Energetics of the reactions was discussed on the bases of the experimental results and the calculated geometries of the isomers. It was concluded that the nucleophilic substitution reaction is responsible for the C₆H₅NH₂⁺ production. Isomer-dependent reactions occurring within the H₂O complexes were also presented, and their energetics was discussed in relation to a barrier height to the substitution reaction.