Differences in the Vibrational Dynamics of H2O and D2O: Observation of Symmetric and Antisymmetric Stretching Vibrations in Heavy Water

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• 作者：Luigi De Marco ; William Carpenter ; Hanchao Liu ; Rajib Biswas ; Joel M. Bowman ; Andrei Tokmakoff
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：May 19, 2016
• 年：2016
• 卷：7
• 期：10
• 页码：1769-1774
• 全文大小：386K
• 年卷期：0
• ISSN：1948-7185

文摘

Water’s ability to donate and accept hydrogen bonds leads to unique and complex collective dynamical phenomena associated with its hydrogen-bond network. It is appreciated that the vibrations governing liquid water’s molecular dynamics are delocalized, with nuclear motion evolving coherently over the span of several molecules. Using two-dimensional infrared spectroscopy, we have found that the nuclear motions of heavy water, D₂O, are qualitatively different than those of H₂O. The nonlinear spectrum of liquid D₂O reveals distinct O–D stretching resonances, in contrast to H₂O. Furthermore, our data indicates that condensed-phase O–D vibrations have a different character than those in the gas phase, which we understand in terms of weakly delocalized symmetric and antisymmetric stretching vibrations. This difference in molecular dynamics reflects the shift in the balance between intra- and intermolecular couplings upon deuteration, an effect which can be understood in terms of the anharmonicity of the nuclear potential energy surface.