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 A²Π_1/2−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 A²Π_1/2(v = 0) state are rationalized using the predicted and observed electronic state distribution. The observed Zeeman tuning of the levels in the A²Π_1/2(v = 0) state is unexpectedly large; this is caused by mixing with the B²Σ⁺ state.