17O NMR Investigation of Water Structure and Dynamics

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• 作者：Eric G. Keeler ; Vladimir K. Michaelis ; Robert G. Griffin
• 刊名：Journal of Physical Chemistry B
• 出版年：2016
• 出版时间：August 18, 2016
• 年：2016
• 卷：120
• 期：32
• 页码：7851-7858
• 全文大小：419K
• 年卷期：0
• ISSN：1520-5207

文摘

The structure and dynamics of the bound water in barium chlorate monohydrate were studied with ¹⁷O nuclear magnetic resonance (NMR) spectroscopy in samples that are stationary and spinning at the magic-angle in magnetic fields ranging from 14.1 to 21.1 T. ¹⁷O NMR parameters of the water were determined, and the effects of torsional oscillations of the water molecule on the ¹⁷O quadrupolar coupling constant (C_Q) were delineated with variable temperature MAS NMR. With decreasing temperature and reduction of the librational motion, we observe an increase in the experimentally measured C_Q explaining the discrepancy between experiments and predictions from density functional theory. In addition, at low temperatures and in the absence of ¹H decoupling, we observe a well-resolved ¹H–¹⁷O dipole splitting in the spectra, which provides information on the structure of the H₂O molecule. The splitting arises because of the homogeneous nature of the coupling between the two ¹H–¹⁷O dipoles and the ¹H–¹H dipole.