Microwave spectrum of the CHF2 radical in the 2A′ ground electronic state: fluorine hyperfine structure alternation in inversion levels

The rotational spectrum of the difluoromethyl radical was observed by microwave spectroscopy. Many b-type R and Q branch transitions accompanied with hyperfine structures due to fluorine and hydrogen nuclei were detected in the 100–400 GHz range. A preliminary analysis of the rotational transitions with IF=0 and 1, where IF=I(F1)+I(F2), resulted in finding fluorine hyperfine structure alternation for inversion levels: IF=0 or 1 components of a particular rotational level correspond to the plus or minus inversion level, depending on the symmetry of the rotational level. The rotational constants and centrifugal distortion constants in both inversion levels were determined by a least-squares analysis for the hypothetical rotational transition frequencies.