Optical Zeeman Spectroscopy of Ytterbium Monofluoride, YbF

The Zeeman-induced shifts and splittings of low-J lines in the OP12 branch of the (0,0) band of the A2Π1/2−X2Σ+ electronic transition of a cold molecular beam sample of ytterbium monofluoride, YbF, have been recorded. The Zeeman spectra for the 171YbF, 172YbF, and 174YbF isotopologues have been analyzed using a standard effective Hamiltonian approach. The magnetic g-factors determined for the A2Π1/2(v = 0) state are rationalized using the predicted and observed electronic state distribution. The observed Zeeman tuning of the levels in the A2Π1/2(v = 0) state is unexpectedly large; this is caused by mixing with the B2Σ+ state.