Abstract
The broad line NMR measurement of protons of adsorbed hydrogen and hydroxyl groups on fine ZnO powder was performed in connection with effects of adsorbed hydrogen on ESR of conduction electrons (CESR) in the accumulation layer. The NMR spectra from the ZnO out-gassed at 400°C showed the existence of two kinds of hydroxyl groups on the surface: one is passively adsorbed when present in high density and the other is in a state with free motions. States of chemisorbed hydrogen are similar to those of hydroxyl groups at 22°C, but chemisorbed hydrogen formed at -120°C is in a state of a migrating motion. When H2 gas was introduced to the ZnO at -120°C, the NMR spectrum became asymmetric, which revealed the presence of a weakly adsorbed hydrogen with 15 ppm of the chemical shift to the low field direction. This species is concluded to be H3+ molecules, which causes an increase in the CESR intensity with discharge of their electrons to the accumulation layer.