The high-resolution infrared spectrum of ethane-1,1,1-D 3 rovibration studies of CH 3CD 3 and 13CH 3CD 3

The infrared spectra of a number of fundamentals of CH ₃CD ₃ and ¹³CH ₃CD ₃ were recorded at ∼0.05 cm ^-1 resolution using a Nicolet FTIR spectrometer. Complete analyses at this resolution were performed for the ν₂ (CD ₃ sym. stretch), ν₇ (CH ₃ asym. stretch), ν₉ (CH ₃ asym. deformation), ν₁₁ (CD ₃ asym. deformation), and ν₁₂ (CD ₃ rock) fundamentals, and sets of upper-state parameters are derived. Perturbations in the ν₉ band are accounted for in terms of an A₁- E Coriolis interaction with ν₃ (CH ₃ sym. deformation), and in the ν₁₁ band in terms of the combined effects of an A₁- E Coriolis interaction with ν₄ (CD ₃ sym. deformation) and an E(± l) - E(∓ l) interaction with ν₁₀ (CH ₃ rock). A small, localized perturbation in ν₇ is identified as due to a higher-order rotational resonance with 2 ν₉². All first- and second-order Coriolis interaction parameters are determined. Limited spectroscopic information is obtained on ν₃, ν₄, and ν₁₀, all of which are extremely weak in the infrared. The perpendicular band analyses enable the centrifugal distortion D_K⁰ constant to be estimated.