19758
J. Phys. Chem. 1996, 100, 19758-19763
Fragmentation Energetics and Dynamics of the Neutral and Ionized Fluorobenzene‚Ar Cluster Studied by Mass Analyzed Threshold Ionization Spectroscopy† Gerhard Lembach and Bernhard Brutschy* Institut fu¨ r Physikalische und Theoretische Chemie, J. W. Goethe UniVersita¨ t Frankfurt, Marie-Curie-Strasse 11, 60439 Frankfurt/Main, Germany ReceiVed: July 15, 1996; In Final Form: October 11, 1996X
Mass-analyzed threshold ionization spectroscopy (MATI) was used for a detailed investigation of the dissociation process of a fluorobenzene‚Ar complex. The threshold ion spectra were recorded for the fluorobenzene monomer and the fluorobenzene‚Ar complex by exciting the chromophore via different vibrational states of the S1. The ion state spectra of the (fluorobenzene‚Ar)+ cation exhibit significant progressions of the van der Waals bending mode bx, which indicates a significant structural change of the complex upon ionization. The disappearance of the threshold ion signal for a certain excess energy in the complex (fluorobenzene‚Ar)+ and the simultaneous appearance of the missing bands in the spectra of the fragment ion give an upper limit for the dissociation energy of the complex in the cationic state. In addition, one feature observed in the fragment ion spectrum of the complex recorded via exciting the S16b1 state reveals the relatively fast predissociation (
