Optical Zeeman spectroscopy of ytterbium monofluoride, YbF.

The Zeeman-induced shifts and splittings of low-J lines in the (O)P(12) branch of the (0,0) band of the A(2)Pi(1/2)-X(2)Sigma(+) electronic transition of a cold molecular beam sample of ytterbium monofluoride, YbF, have been recorded. The Zeeman spectra for the (171)YbF, (172)YbF, and (174)YbF isotopologues have been analyzed using a standard effective Hamiltonian approach. The magnetic g-factors determined for the A(2)Pi(1/2)(v = 0) state are rationalized using the predicted and observed electronic state distribution. The observed Zeeman tuning of the levels in the A(2)Pi(1/2)(v = 0) state is unexpectedly large; this is caused by mixing with the B(2)Sigma(+) state.