Assignment of methyl cyanide FIR laser lines

High-Resolution Infrared Spectrum of CD3CN: Analysis of the Interacting ν3 and ν6 Bands and Evaluation of the A0 Constant

“…The first addition is naturally the essential (2, 2) resonance in ν 6 . As soon as it was possible to sketch energy level diagrams for v 3 = 1 and for v 6 = 1, 6 = ±1, it was clear that in addition to the Coriolis resonance there is also an (1, −2) resonance which is most effective just in the same subbands.…”

“…A series of Q branches in the ν 6 band of CD 3 CN to illustrate the effects of the ν 3 /ν 6 Coriolis resonance. The shape of R Q 0 is strikingly different from adjacent Q branches, indicating a giant -doubling.…”

“…The ν 3 band proved to be extremely weak. Lines could be found only in three subbands, K = 8-10, near the crossing of the strong Coriolis resonance ν 3 /ν 6 , where the interaction lends enough intensity to the ν 3 lines so that they become detectable. The situation is similar to that encountered for CH 3 CN (8) but there in the corresponding band only two subbands were observable.…”

“…In that study the inclusion of the hot bands ν 6 + ν 8 − ν 8 played an important role. The spectrum of the ν 6 band has also been applied in assigning some CD 3 CN FIR laser lines (6).…”

“…Their analysis was based on the ν 6 lines and on the effects of the ν 3 /ν 6 Coriolis resonance, but they had no direct observations for ν 3 . We have recorded a 1 E-mail: Seppo.Alanko@oulu.fi.…”