Abstract
Gas-phase E.P.R. spectra for SO(1Δ) in the J = 3 rotational level have been observed using microwaves at 4·46 GHz. Measurements of the resonance lines were made for the C-band spectra of the J = 3 and 2 levles and for the X-band (9·17 GHz) of the J = 2 level. Analysis of the spectra revealed an anomaly in the molecular g values for the J = 2 and 3 levels. This is well explained by mixing with the 1Φ electronic states. It is shown that the E.P.R. results are completely consistent with the rotational constant obtained by microwave spectroscopy.