Spectral signatures of hydrated proton vibrations in water clusters
Spectral signatures of hydrated proton vibrations in water clusters
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DOI：
10.1126/science.1113094
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发表时间：
2005-06-17
期刊：
影响因子：
56.9
通讯作者：
Jordan, KD
中科院分区：
文献类型：
--
作者：
Headrick, JM;Diken, EG;Jordan, KD
测量水的pH值的容易性掩盖了这样一个事实，即目前对水合质子没有明确的分子描述。例如，散装含水酸的中红外光谱过于分散，无法确定假定的本征（H3O+）和Zundel（H5O2+）离子核心的作用。为了揭示局部环境的过剩电荷，我们报告质子化水簇的振动光谱如何演变的大小范围从2到11个水分子。签名带表示嵌入本征或Zundel限制形式观察到在所有的光谱中的三个和五个成员的集群除外。这些独特的物种显示带出现在中间的能量，反映了不对称溶剂化的核心离子。总之，这些数据揭示了水合环境中细微变化的明显光谱影响。
The ease with which the pH of water is measured obscures the fact that there is presently no clear molecular description for the hydrated proton. The mid-infrared spectrum of bulk aqueous acid, for example, is too diffuse to establish the roles of the putative Eigen (H3O+) and Zundel (H5O2+) ion cores. To expose the local environment of the excess charge, we report how the vibrational spectrum of protonated water clusters evolves in the size range from 2 to 11 water molecules. Signature bands indicating embedded Eigen or Zundel limiting forms are observed in all of the spectra with the exception of the three- and five-membered clusters. These unique species display bands appearing at intermediate energies, reflecting asymmetric solvation of the core ion. Taken together, the data reveal the pronounced spectral impact of subtle changes in the hydration environment.