OVERTONE BANDS 2-UPSILON-3 OF (CH3I)-C-12 AND (CH3I)-C-13

The infrared bands 2ν3 of 12CH3I and 13CH3I have been investigated at a resolution of about 0.003 cm-1. Both the bands, one at 1059.9934 and the other at 1028.1201 cm-1, respectively, are very similar and they have a special feature, a bandhead, in the R branch. In both the bands about 1100 lines with Jmax ≈ 60 and Kmax = 12 have been assigned. In the analyses the model for an unperturbed parallel band could be used. In the fits the H constants fixed to ground state values have been included. Standard deviations of 0.11 × 10-3 cm-1 and 0.13 × 10-3 cm-1, respectively, have been attained. Molecular constants related to the bands are given. The hot bands 3ν3 - ν3 have also been studied and the results are very similar to these from the corresponding 2ν3 bands. The assignments of some optically pumped FIR laser lines are discussed. © 1990.