The HeBr2van der Waals complex has been observed in a free jet expansion. The complex was detected by laser excitation of the bands associated with the Br2(Bminus;X) system. High resolution (0.05 cmminus;1) spectra have been recorded for the 11hyphen;0 to 38hyphen;0 bands. The rotational structure has been resolved for several bands and the analysis is found to be consistent with a rigidThyphen;shaped geometry. The distance from the Br2bond center to the He atom is 3.8 A and 3.7 A for the excited and ground states, respectively. Vibrational predissociation of the Hendash;Br2bond has been observed via homogeneous broadening of the rotational lines. Predissociation rates, derived from the line shape data, showed a strong dependence on the Br2vibrational excitation. Rates varied from 1010thinsp;sminus;1forvprime;=11, up to 5times;1011thinsp;sminus;1forvprime;=38. The data can be adequately described by a simple lsquo;lsquo;energy gaprsquo;rsquo; model for the predissociation probability.
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