Hyperfine structure of the SiC radical

The millimeter-wave rotational spectrum of the free 29SiC radical in the X3Π ground state, produced in a low-pressure glow discharge through SiH4 and CO, was detected with the same reactive-molecule spectrometer used earlier to detect SiC and Si13C. Eleven rotational transitions, all but two with resolved hyperfine structure, were measured between 195 GHz (J=4→5) and 372 GHz (J=8→9). Well-resolved hyperfine splittings in the three fine-structure ladders allow determination of the magnetic hyperfine constants to 2% or better.