کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1401277 | 1501704 | 2016 | 4 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Understanding the symmetric line shape in the 17O MAS spectra for hexagonal ice
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آلی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Solid-state 17O Magic-Angle Spinning (MAS) nuclear magnetic resonance (NMR) spectra of 17O-enriched hexagonal ice, [17O]-Ih, between 173 and 253 K were presented. Marked changes in the line shape were clearly observed, indicating water molecular reorientation in the crystal structure. At 173 K, molecular motions were considered to be frozen and analysis of the 1D MAS spectrum yielded the following parameters: quadrupole coupling constant (CQ) = 6.6 ± 0.2 MHz and asymmetry parameter (ηQ) = 0.95 ± 0.05. At 232 K and above, contrary to the conventional explanation, pseudo-symmetric line shapes appeared in the 17O MAS NMR spectra arising from the contribution of second-order quadrupole interactions. As a chemical exchange model to describe these isotropic 17O MAS NMR spectra, a modified Ratcliffe model, which consider the effects of proton disorder, was proposed, and the resulting theoretical spectra could well reproduce the experimental spectra.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Structure - Volume 1113, 5 June 2016, Pages 108-111
Journal: Journal of Molecular Structure - Volume 1113, 5 June 2016, Pages 108-111
نویسندگان
Kazuhiko Yamada, Shinobu Oki, Kenzo Deguchi, Tadashi Shimizu,