RE13		15min5:00

JASON O. CLEVENGER, Department of Chemistry, MIT, Cambridge, MA 02139; AND JOEL TELLINGHUISEN, Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235.

The B(1/2 ²P_3/2) -> X(1/2 ²⁺) transition in XeBr was recorded in high resolution, using a CCD array detector to record spectra from Tesla discharge sources containing isotopically pure ¹³⁶Xe with ⁸¹Br₂ or ⁷⁹Br₂. The high signal/noise capabilities of the detector permitted the measurement of discrete vibrational structure in this system, which has normally been treated as a purely bound-free transition. The assignments comprised 119 v'-v'' bands for ¹³⁶Xe⁸¹Br and 86 for ¹³⁶Xe⁷⁹Br, spanning v'= 0-33 and v''= 0-16. The van der Waals ground state was analyzed through fits to the customary polynomials and to near- dissociation expansions. Franck-Condon calculations were used to locate the X-state potential on the internuclear axis relative to the B state, which was modeled as a Rittner potential. The following fundamental spectroscopic constants (units cm^-1, for ¹³⁶Xe⁸¹Br) were obtained from the analysis: T_e' = 35 863.2, \omega_e' = 135.72, \omega_ex_e' = 0.32, \omega_e'' = 25.7, \omega_ex_e' = 0.62. The ground state has a dissociation energy D_e'' = 254 \pm 2 cm^-1 and supports 24 bound vibrational levels.