Assignment of Infrared and Far-Infrared Transitions of CH₂CF₂

Starting from the Watson A-reduced Hamiltonian and considering the infrared transitions with ΔK_a = 0, ΔK_c = ±1 (A-type) or ΔK_a = ±1, ΔK_c = ±1 (B-type), and the far-infrared transitions with ΔK_a = 0,±2 and ΔK_c = ±1, we calculate all the possible infrared absorption and far-infrared emission transitions of the ν₄ and ν₉ bands of 1,1-difluoroethylene (CH₂CF₂) pumped by 10P10 and 10P12 CO₂ laser lines. We assign four previously unassigned CH₂CF₂ far-infrared laser lines (291.3 µm, 339.3 µm, 349.5 µm and 657.9 µm), where K_a and K_c represent the quantum number K of the limiting prolate top and the limiting oblate top, respectively. The 291.3 µm line is identified as being generated from the cascade transition. The assignment of the 288.5µm line by Lafferty et al. (J. Mol. Spectrosc. 87(1981)416) is also confirmed.