Intracavity laser spectroscopy of VO: Hyperfine parameters and electron configuration of the B4Π state

The low-J structure of the B4Π-X4Σ− (1, 0) band of VO has been investigated at sub-Doppler resolution by intracavity laser-induced fluorescence spectroscopy. Values of the principal hyperfine parameters a and (b + c) for the B4Π state have been deduced from the lines of the 4 Π 5 2 -X and 4 Π 3 2 -X subbands: a = 0.00964 cm−1 and (b + c) = −0.01295 cm−1. Estimates of the dipolar parameter c show that it is small compared to b, so that the Fermi contact parameter b is sizeable and negative; this allows the electron configuration of the B4Π state to be assigned as (3dδ)2(3dπ)1(4sσ)1. The very great sensitivity of intracavity laser spectroscopy in the visible region is emphasized.