The magnetic field dependence of the polarization of deuterated-butanol

A joint group of SMC and PSI reported several years ago a surprising fact that polarization of the deuterated butanol and propanediol disappears at 5 Tesla. Independently, Bonn group measured polarization for propanediol at 3.5 Tesla and gave nearly 20% for positive and negative enhancements. Polarization for deuterated butanol obtained so far at 2.5 Tesla is about 50% using the frequency modulation to the microwave in dynamic nuclear polarization. These facts suggest there must be some optimum magnetic field to give the maximum polarization. Motivated by them, we tried to measure the polarization of deuterated butanol at 2.5, 2.25 and 2.0 Tesla under the two different temperatures of 0.4 and 0.48 K. The results show that the polarization increases with magnetic field up to 2.5 Tesla. (author)