Abstract
A saturation NMR method is introduced with which near a Zeeman-tunneling resonance the ratio of the Zeeman and tunneling specific heats as well as the Zeeman-tunneling coupling time can be determined. In addition, by measurement of the coupling time at different Larmor frequencies the tunneling splitting can be obtained with good accuracy (∼1%). This method is useful in the tunneling splitting range 102 to 1 μeV, which is just below the resolution limit of inelastic neutron spectroscopy.