Far-Infrared Laser Stark Spectroscopy of 1,1 Difluoroethylene

The far-infrared laser Stark spectrum of 1,1 difluoroethylene (H2C=CF2) has been investigated with the 311 µm line of the hydrogen cyanide (HCN) laser. Numerous families of absorption lines have been observed for both parallel and perpendicular polarizations up to 60 000 V/cm. Three families of resonances have been identified as J(Ka,Kc) = 41(35,7) ← 40(33,8), 40(36,5) ← 39(34,6) and 43(35,8) ← 42(33,9). The Stark shift for the first two transitions can be adequately explained by quasi-first-order calculations, whereas the Stark shift for the third transition requires second-order corrections. The zero-field frequencies for these transitions have been experimentally determined and are reported with fractional uncertainties up to a few parts in 10 6