High resolution infrared spectrum and analysis of the 2v 3, 3v 3-v 3 and v 1-v 3 bands of CF3 Br

The vibro-rotational spectrum of CF3Br in natural isotopic abundance has been recorded in the 14 ?m region using a tunable diode laser spectrometer. The difference band v 1-v 3 (around 732 cm-1), the overtone 2v 3, as well as the hot-band 3v 3-v 3, (both around 700 cm-1) of both isotopic species, CF3 79Br and CF3 81Br, were analysed. The K-structure could be resolved for most of the bands observed. Accurate molecular constants for the v 3, 2v 3 and 3v 3 levels were determined from a least squares fit of the observed transition frequencies. The validity of the additivity rule for ? A and ? B constants is discussed in general and in particular for all parallel bands of CF3Br which involve the v 3 vibration.