ROVIBRATIONAL ANALYSIS OF WEAKER BANDS (NU(3)-NU(3), NU(3)+NU(4)+NU(5)-NU(3) AND NU(1)+NU(5)) OF (CH3BR)-BR-79 IN THE RANGE OF 2.5 MU-M(NU(4)+NU(6), NU(2)+NU(3)+NU(4))

All the bands of the (CH3Br)-Br-79 isotopomer quoted in the title have been studied in high resolution (0.006 cm(-1)). A least squares fit o ver 580 lines (194 being zero-weighted) of nu(3) + nu(4) + nu(6)E, acc ording to an unperturbed model, gave a r.m.s. deviation of 0.005 cm(-1 ) with quite reasonable molecular constants. A least squares fit over 824 lines (171 being zero-weighted) of both nu(2) + nu(3) + nu(4) - nu (3) and nu(3) + nu(4) + nu(5) - nu(3) hot bands, linked by the x-y Cor iolis resonance which connects the nu(2) and nu(5) modes [C. di Lauro and I.M. Mills, J. Mol. Spectrosc, 21 (1966) 386], was achieved accord ing to a model taking also into account the l(2,2) resonance [M.-L. Gr enier-Besson, J. Phys. (Paris), 21 (1960) 555, and G.J. Cartwright and I.M. Mills, J. Mel. Spectrosc, 34 (1970) 415] inside the nu(4) mode; it gave a r.m.s. deviation of 0.027 cm(-1). The nu(2) + nu(3) + nu(4) - nu(3) band overlaps the nu(1) + nu(5) band on its Delta K = -1 side, making quite difficult the assignments of this latter band, 1020 line s of which have nevertheless been identified. Moreover nu(1) + nu(5) i s strongly perturbed by both perpendicular components of the nu(3) + 2 nu(5) + nu(6) band, which are too weak to be normally observed and ar e only reached because of their interactions with nu(1) + nu(5). (C) 1 997 Elsevier Science B.V.