Microwave spectrum of the boron monoxide radical, BO

Abstract

The microwave spectrum of the boron monoxide radical in the ground electronic state X 2Σ+ has been observed by using a glow discharge cell spectrometer. The boron monoxide radical was generated in an absorption cell by a glow discharge in a gaseous mixture of boron trichloride, nitric oxide, and nitrogen. The observed transitions were N=1–0 and 3–2 in 100 and 300 GHz regions, respectively. The latter transition was observed by using a frequency multiplier working in the 300 GHz region as a microwave source. The spectra of two isotopic species 11BO and 10BO were analyzed to yield molecular parameters including the rotational constants, centrifugal distortion constants, spin-rotation interaction constants, magnetic hyperfine interaction constants, and nuclear quadrupole interaction constants. The spin density of the unpaired σ electron was calculated from the magnetic hyperfine coupling constants and was found to be in good accordance with the result of ab initio calculations.