Resonant two-photon ionization spectra of the van der Waals complexes: C(6)H(5)X center dot center dot center dot N-2(X=F, Cl, Br)

The one-color resonant two-photon ionization technique is employed to study jet-cooled van der Waals (vdW) clusters of halobenzene and nitrogen through the S-0-->S-1 transition around the (0) over bar(0)(-0) band. The spectra obtained exhibit rich information about the clusters' intermolecular vdW vibrational modes and their solvent internal rotation. We have tentatively assigned all the observed spectral features to a single isomer of C(6)H(5)X ... N-2 (X=F, Cl, Br). The influence of X on the vdW vibrations and the internal rotation of N-2 in the complex is investigated. The analysis of the influence of X on the (0) over bar(0)(-0) spectral shift suggests that the change in vdW interaction energy; upon electronic excitation is mainly due to the dispersion term. (C) 1996 American Institute of Physics.