Fourier transform high resolution study of the 3v₂, 2v₂+v₅, v₂+2v5/0 and 3v5/±1 rovibrational bands of CH₃⁷⁹Br from 3830 cm⁻¹ to 4300 cm⁻¹

Abstract

About 2000 lines of the four bands quoted in the title have been assigned. A root-mean-square deviation of about 0·0235 cm⁻¹ has been achieved by a least-squares fit over 1771 lines. For this purpose, a model involving 15 levels, linked either by the x-y Coriolis resonance between the v ₂ and v ₅ modes or by slight anharmonic resonances, was used. Several perturbations remain unexplained in the 3v 5/±1 band, the centre of which is shifted by the Fermi resonance between the v ₅=3^±1 and the (v ₁=1,v ₅ ^±1), levels.