Jet-cooled diode laser spectra of CF3Br in the 9.2 μm region and rovibrational analysis of symmetric CF3 stretching mode

Abstract

Pulsed slit-jet high resolution (up to 0.0009 cm⁻¹ FWHM) infrared diode laser spectra of CF₃Br, with natural isotopic abundance, were obtained in the region around 9.2 μm at the rotational temperature of about 50 K. In addition, diode laser spectra at reduced temperature (200 K) were recorded. We present here the rovibrational analysis of the ν₁ fundamental in the range 1075–1090 cm⁻¹. The fine structure of many P(J) and R(J) clusters has been well resolved for the first time. The assignment of rovibrational transitions has been accomplished up to K = 27, J = 63 for CF⁷⁹₃Br and K = 33, J = 62 for CF⁸¹₃Br. A total of 636 (CF⁷⁹₃Br) and 880 (CF⁸¹₃Br) lines were used in the final fit and a very accurate set of molecular constants, including the quartic centrifugal distortion coefficients for the v₁ = 1 state of both the bromine isotopologues, was obtained. In addition, spectral features belonging to the ν₁ + ν₆ − ν₆ hot band were unambiguously identified and a set of spectroscopic parameters were determined.