High-resolution infrared study of 1,1-ethylene-D2 in the 2000- to 1200-cm−1 region

The infrared spectrum of H₂CCD₂ was investigated in the region 2000-1200 cm^?1 at a resolution of ～0.05 cm^?1. Complete analyses of four type-A bands are reported-the CC stretch, ν₂, the CH₂ deformation, ν₁₂, and the overtones of the CD₂ and CH₂ wagging fundamentals, 2ν₇ and 2ν₈. Localized perturbations are identified and taken into account in the analyses, enabling the perturbing vibrational levels to be located accurately and the interaction parameters to be determined. In the case of ν₁₂, Fermi resonance with 2ν₁₀ has a global effect, and causes a bandhead to be formed in the K_a subband series.