Electronic Spectrum of the .alpha.,.alpha.-Difluoroethyl Radical

The first electronic spectrum of the α,α-difluoroethyl radical (CF 2 CH 3 ) was observed between 335 and 475 nm by resonance-enhanced multiphoton ionization (REMPI) spectroscopy. The spectrum arises from two-photon resonances with a 3p Rydberg state. A third laser photon ionized the radicals. The electronic origin is tentatively assigned at ν 00 =43 275 cm -1 , and the vibrational progression is assigned as the ν 9' (CF 2 wag)= 530 cm -1 . In support of these spectral assignments, we report ab initio calculations at the MP2/6-31G * , G1, and G2 theory levels which found the optimum structures, vibrational frequencies, and relative energies of CF 2 CH 3 , CF 2 CH 3 + , CHF 2 CH 2 , and CHF 2 CH 2 +