CHARACTERIZATION OF THE KRCL2 AND XECL2 VANDERWAALS ISOMERS

The observation of van der Waals isomers of KrCl2 and XeCl2 by two-laser pump-probe spectroscopy is reported. Both complexes are found to be T-shaped in the ground electronic state and at least up to upsilon = 11 in the B excited electronic state. Analysis of the Cl2 fragment rotational distributions yields a van der Waals dissociation energy of 236.6 +/- 2.0 cm-1 (2.84 +/- 0.02 kJ/mol) in the ground state for KrCl2 and 286.3 +/- 1.1 cm-1 (3.44 +/- 0.01 kJ/mol) in the ground state for XeCl2. The fragment rotational distributions suggest that the clusters may vibrationally predissociate via an intramolecular vibrational redistribution process, but the large reduced mass of the complexes causes several collisions to occur before complete dissociation. Several other observations are reported which suggest that electronically nonadiabatic relaxation channels are available to the complexes and compete with vibrational predissociation.