JINHAI CHEN, TIMOTHY C. STEIMLE, Department of Chemistry and Biochemistry, Arizona State University, Temple, AZ 85287; ZHONG WANG, TREVOR J. SEARS, Department of Chemistry, Brookhaven National Laboratory, Upton, NY 11973-5000.

The polarization signals induced by the Zeeman effect in the X4 Delta leftarrow F4 Delta band of FeH have been proposed for use in the characterization of stellar magnetic fields. While the magnetic tuning of the low-rotational levels of the X4 Delta7/2 state has been measured by pure-rotational laser magnet resonance spectroscopy, the strength of the Zeeman effect in the upper state is unknown. Here we report on the magnetic tuning of levels in (v=1)F4 Delta7/2 state derived from the analysis of the optical Zeeman spectra of the X4 Delta7/2 leftarrow F4 Delta7/2 (1,0) band system. The Zeeman broadening and splitting of the Q(3.5)( nu=11356.72~ cm-1) transition were successfully modeled using a traditional effective Hamiltonian. The determined magnetic gL-factor is 1.079(8) when the gS-factor is constrained to 2.002. Plausible explanations for deviation of gL from the expected value of unity will be given. The determined parameters are used to predict the magnetic tuning of the X4 Delta7/2 leftarrow F4 Delta7/2 (1,0) features for fields comparable to those found in sunspots.