Laser-induced fluorescence studies of jet-cooled CF2: determination of أ-state stretching frequencies

Laser-induced fluorescence (LIF) excitation spectra of the CF2 Ã 1B1←X̃ 1A1 system around 250 nm has been measured under supersonic free-jet conditions. CF2 radical was produced by DC-discharge of CF4 seeded in argon. Previously ambiguous assignments of the Ã-state stretching frequencies have been experimentally determined to be ν1′=1012.1 cm−1 and ν3′=1180.2 cm−1, by analyzing the subband spectra attributed to some of the observed progressions (20n, 10120n−2 and 20n311 (n≤6)) in which 21 vibronic bands were unambiguously labeled. The measured Ã-state stretching frequencies do not support King et al.ʹs assignments [D.S. King, P.K. Schenck, J.C. Stephenson, J. Mol. Spectrom. 78 (1979) 1], but are in good agreement with Cameron et al.ʹs theoretical assertions [M.R. Cameron, S.H. Kable, G.B. Bacskay, J. Chem. Phys., 103 (1995) 4475].