Fluorescence of CF2(B1, 040,K' = 9) excited by the 253.7 nm Hg resonance line

Resonance fluorescence spectra of CF₂(¹B₁, 040, K' = 9) excited at 253 7 nm have been observed in the photolysis of C₂F₄ using a low-pressure mercury lamp. At low C₂F₄ pressures, the spectra with a series of doublet hands from 254 to 400 nm were consistent with the transitions from ¹B₁, 040, K'=9 to ¹A₁, 0v'₂0, K' = 8, 10, and also to ¹A₁, 1v'₂0, K' = 8, 10 The appearance of doublet bands (Δ K = ±1) provides clear evidence that the transition is of the perpendicular type.