INFRARED DIODE-LASER SPECTROSCOPY OF FUNDAMENTAL AND HOT BANDS OF BBR(X-1-SIGMA(+))

Infrared absorption spectra of the four common isotopic forms of the t ransient molecule BBr ((BBr)-B-11-Br-79, (BBr)-B-11-Br-81, (BBr)-B-10- Br-79, and (BBr)-B-10-Br-81) have been observed in natural abundance. The spectra were detected in the region between 650 and 720 cm(-1) usi ng diode laser spectroscopy of a BBr3/He ac discharge. Over 150 lines consisting of both fundamental and hot bands up to upsilon '' = 5 have been fitted to Watson's isotopically invariant coefficients (U-kl). S pectroscopic parameters for each isotopomer could be derived from thes e coefficients; for (BBr)-B-11-Br-79, omega(e) = 685.1892(15) cm(-1) a nd omega(e)x(e) = 3.73632(95) cm(-1). The equilibrium dissociation ene rgy obtained from Dunbam's expanded Morse potential is 32 711(43) cm(- 1). (C) 1998 Academic Press.