Laser Induced Fluorescence Study of the HeBr2 Van Der Waals Complex

摘要

The HeBr2 van der Waals complex has been observed in a free jet expansion. The complex was detected by laser excitation of the b ands associated with the Br2(B - X) system. High resolution (0.05/cm) spectra have been recorded for the 11-0 to 38-0 bands. The rotational structure has been resolved for several bands and the analysis is found to be consistent with a rigid T-shaped geometry. THe distance from the Br2 bond center to the He atom is 3.8 lA and 3.7 A for the excited and ground states, respectively. Vibrational predissociation of the He-Br2 bond has been observed via homogeneous broadening of the rotational lines. Predissociation rates, derived from the line shape data, showed a strong dependence on the Br2 vibrational excitation. Rates varied from 10 to the 10th power/s for nu' = 11, up to X10 to the 11th power/for nu' = 38. The data can be adequately described by a simple energy gap model for the predissociatio probability.