The microwave spectrum of the CF radical

Rotational transitions of the CF radical in both the 2Π1/2 and 2Π3/2 ground electronic states were observed in the region up to 300 GHz by using a source-frequency modulation microwave spectrometer. The CF radical was generated directly in a free-space absorption cell by a dc discharge in carbon tetrafluoride containing a small amount of methyl fluoride. The rotational constant, the centrifugal distortion constant, and the Λ-type doubling constants, as well as all four hyperfine coupling constants a, b, c, and d of the fluorine nucleus, were determined with good precision. From the observed hyperfine coupling constants the unpaired-electron spin and spatial (orbital) distributions 〈1/r3〉s, 〈(3 cos2 χ−1)/r3〉s, 〈sin2 χ/r3〉s, and 〈1/r3〉0 were calculated and discussed in terms of a simple molecular-orbital picture.