ChemInform Abstract: THE MICROWAVE SPECTRUM OF THE TRIFLUOROMETHYL RADICAL

The microwave spectrum of the trifluoromethyl radical in the ground 2A1 state has been observed by using a source frequency modulation spectrometer. The CF3 radical was generated directly in the absorption cell by a glow discharge in trifluoroacetic acid anhydride (CF3CO)2O. The observed transitions included N = 4 ← 3, 5 ← 4, and 6 ← 5, all of which are resolved into K as well as fine and hyperfine structure components. A magnetic hyperfine Hamiltonian was derived for three identical nuclei with a spin of 1/2 (the fluorine nuclei) in a doublet symmetric‐top molecule, in order to analyze the observed spectrum. Most of the hyperfine structure could be explained by considering the total nuclear spin operator I0 = JiIi, except for the K = 1 transitions; some of them were clearly resolved into doublets and the observed splittings allowed us to determine the additional dipole–dipole hyperfine interaction constant ‖ Taa−Tbb ‖. The rotational constant B0 was determined to be 10 900.9118(52) MHz, with 2.5 times th...