A B C
Z. Naturforsch. 2014, 69b, 786 – 792
doi:10.5560/ZNB.2014-4070
Line-Shape Analyses of Solid-state 17O NMR Spectra for Hexagonal Ice
Kazuhiko Yamada1, Kenzo Deguchi2, Tadashi Shimizu2, and Junji Watanabe3
1 Interdisciplinary Science Unit, Multidisciplinary Sciences Cluster, Research and Education Faculty, in charge of Science Research Center, Kochi University, Oko Campus, Nankoku, Kochi 783-8505, Japan
2 National Institute for Materials Science, Tsukuba, Ibaraki 305-0003, Japan
3 Department of Organic and Polymeric Materials, Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552, Japan
Reprint requests to Kazuhiko Yamada. Phone: +81-88-880-2184. Fax: +81-88-880-2185. E-mail: kyamada@kochi-u.ac.jp
Received March 15, 2014 / published online July 8, 2014
We present the results of experimental and theoretical investigations of line shapes in solid-state 17O NMR spectra of hexagonal ice, Ih. Stationary 17O NMR spectra of Ih at temperatures from 143 to 280 K were obtained at 11.7 and 16.4 T. Line shapes changed drastically as the temperature was increased from 143 to 243 K; at 253 K and above, pseudo-isotropic line shapes appear, indicating the presence of reorientational motions. We find that Ratcliffe's model, which involves twelve orientations and four-step jumps for water reorientational motions, is effective for analyzing the NMR spectra at temperatures below 243 K. The present analysis demonstrates that the isotropic line shapes arise from proton disorder with respect to the solid-state 17O NMR time scale, producing pseudo-icosahedral motional averaging that can completely average out second-order quadrupole interactions.
Key words: Hexagonal Ice, Solid-state 17O NMR, Molecular Dynamics
Full-text PDF