Study of the spectrum of CH379Br between 1520 and 1700 cm−1: The ν3 + ν6 and the ν5 rovibrational bands

New analysis of the Coriolis-interacting v2 and v5 bands of CH379Br and CH381Br

“…Comparison with the parameters of [10] and [11] shows that we have improved the determination of all parameters. Two additional parameters were needed to describe the Coriolis-type interaction in our fits, namely a J-dependent term C This perturbation is also seen in Fig.…”

“…The same problem was encountered by Badaoui et al [21] in their study of the v 2 / v 5 dyad of D 3 SiF near 700 cm À1 . Like them we tried to contrain C 11 to different values in a small range, and found out that the minimum root-mean-square deviation of our fit was obtained when C ð1Þ 11 is fixed to 0.1813 cm À1 for CH 3 79 Br and 0.1806 cm À1 for CH 3 81 Br. Model II obeys perfectly the Lobodenko's Second Form; i.e., q t , d t , a BB nt , and f K nt (related to our parameters…”

“…In the final fits, for CH 3 79 Br, 430 line positions of v 5 taken from [11] (with J max 6 65 and 8 6 K 6 16), and 3783 (3704) line positions obtained in this work of v 2 and v 5 (with J max 6 68 and K max 6 11) in the 1200-1650 cm À1 spectral region were fitted with a rootmean-square (RMS) deviation of 0.0007 (0.0006) cm À1 , respectively, for CH 3 79 Br and CH 3 81 Br, which represents a significant improvement over previous studies. All the data set was weighted unity.…”

“…Anttila et al [10] measured about 2990 rovibrational transitions in v 2 (centered around 1305.9 cm À1 ) and v 5 (centered around 1442.9 cm À1 ), with J up to 57, and fitted them by taking into account the Coriolis and ''lð2; 2Þ'' interactions. In 1989, Ouahman et al [11] published an infrared spectroscopic study at higher wavenumbers, between 1520 and 1700 cm À1 involving the combination band v 3 þ v 6 and high values of K (7-16) of the v 5 band of CH 3 79 Br. In that work, a model taking into account the ''lð2; 2Þ'' resonance of v 5 and the Coriolis resonance between v 5 and v 2 was used.…”

“…However, these authors did not see any evidence for interaction between v 3 þ v 6 and v 5 . About 74 lines of the v 2 band, taken from [10], combined with 577 lines of v 5 and 443 lines of v 3 þ v 6 were used in [11].…”