Submillimeter-wave spectrum of the FCO radical

The submillimeter-wave spectrum of FCO has been measured using a backward-wave oscillator based spectrometer in conjunction with a free space absorption cell. The FCO radical has been produced in glow discharge plasma of a gaseous mixture of F₂CO, Ar, and He. A total of 109 a-type, R-branch lines have been measured in the 355-638 GHz region and have been analyzed together with the low-J transitions observed by means of Fourier Transform microwave spectroscopy H. Habara, S. Yamamoto, J. Mol. Spectrosc. 207 (2001) 238]. Twenty-one molecular constants have been determined accurately including the fine and hyperfine interaction constants. Comparison of the hyperfine constants with ab initio values and matrix electron spin resonance data has been made.