FRAGMENTATION ENERGETICS AND DYNAMICS OF THE NEUTRAL AND IONIZED FLUOROBENZENE-CENTER-DOT-AR CLUSTER STUDIED BY MASS-ANALYZED THRESHOLD IONIZATION SPECTROSCOPY

Mass-analyzed threshold ionization spectroscopy (MATT) was used or a d etailed investigation of the dissociation process of a fluorobenzene . Ar complex. The threshold ion spectra were recorded for the fluoroben zene monomer and the fluorobenzene . Ar complex by exciting the chromo phore via different vibrational states of the S-1. The ion state spect ra of the (fluorobenzene . Ar)(+) cation exhibit significant progressi ons of the van der Waals bending mode b(x), which indicates a signific ant structural change of the complex upon ionization. The disappearanc e of the threshold ion signal for a certain excess energy in the compl ex (fluorobenzene . Ar)(+) and the simultaneous appearance of the miss ing bands in the spectra of the fragment ion give an upper limit for t he dissociation energy of the complex in the cationic state. In additi on, one feature observed in the fragment ion spectrum of the complex r ecorded via exciting the S(1)6b(1) state reveals the relatively fast p redissociation (<4 ns) of the complex, if the vibrational energy in th e S-1 state exceeds the binding energy D-1 (D-1<302 cm(-1)).