Hyperfine and spin–orbit structure of the 4Δ<i>i</i> ground state of CoO

Abstract

A detailed examination of the structure of the 4Δi ground state of gaseous CoO has been carried out from analysis of the electronic spectrum near 6300 Å, 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 components at sub-Doppler resolution, permitting the hyperfine parameters, a=0.02295 cm−1 and (b+c)=−0.01117 cm−1, to be derived; from the negative value of the contact interaction the electron configuration is established as (4sσ)2(3dδ)3(3dπ)2. The wavelength-resolved fluorescence experiments have given the relative positions of the four spin–orbit components of the X 4Δi state to ±0.3 cm−1. Based on these measurements, a pair of subbands sharing a common electronic upper level, but with the Ω=5/2 and 7/2 components of the ground state as lower levels, has been recognized. Rotational analysis of Doppler-limited intracavity spectra of these two subbands has given an accurate value for the Ω=5/2–7/2 separation as 304.321±0.007 cm−1.