HYPERFINE AND SPIN-ORBIT STRUCTURE OF THE (4)DELTA(I) GROUND-STATE OFCOO

A detailed examination of the structure of the 4DELTA(i) ground state of gaseous CoO has been carried out from analysis of the electronic sp ectrum near 6300 angstrom, using intracavity dye laser and wavelength- resolved fluorescence methods. The intracavity experiments have given the details of the hyperfine structure of the two lowest spin-orbit co mponents at sub-Doppler resolution, permitting the hyperfine parameter s, a = 0.0229(5) cm-1 and (b+c) = -0.0111(7) cm-1, to be derived; from the negative value of the contact interaction the electron configurat ion is established as (4ssigma)2 (3ddelta)3(3dpi)2. The wavelength-res olved fluorescence experiments have given the relative positions of th e four spin-orbit components of the X 4DELTA(i) state to +/- 0.3 cm-1. Based on these measurements, a pair of subbands sharing a common elec tronic upper level, but with the OMEGA = 5/2 and 7/2 components of the ground state as lower levels, has been recognized. Rotational analysi s of Doppler-limited intracavity spectra of these two subbands has giv en an accurate value for the OMEGA = 5/2-7/2 separation as 304.321 +/- 0.007 cm-1.