Anharmonicity of the Bending and Stretching Vibrations Observed in Extended X-Ray Absorption Fine Structure of Tetrahedral Molecules
Anharmonicity of the Bending and Stretching Vibrations Observed in Extended X-Ray Absorption Fine Structure of Tetrahedral Molecules
复制标题
四面体分子的扩展X射线吸收精细结构中观察到的弯曲和拉伸振动的非调和性
DOI：
10.1143/jpsj.65.3901
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发表时间：
1996
影响因子：
1.7
通讯作者：
T. Ohta
中科院分区：
文献类型：
--
作者：
T. Yokoyama;Y. Yonamoto;T. Ohta
测量和分析了MBr 4（M=C，Si，Ge）四面体体系的扩展X射线吸收精细结构（EXAFS）谱的温度依赖性。通过累积展开技术的EXAFS分析，可以获得包括三阶非谐性在内的力常数信息。实验得到的二阶累积量与振动数据的预期值吻合得很好，三阶累积量也被成功地确定。对于第一近邻（NN）Br-M壳层，伸缩运动对EXAFS的贡献明显，而对于第二近邻Br-Br壳层，弯曲模对累积量的贡献很大，尤其是对三阶非谐性的贡献更大.得到的力常数相互比较，并讨论了观察到的弯曲非谐性的起源。
We have measured and analyzed the temperature dependence of extended X-ray absorption fine structure (EXAFS) spectra of tetrahedral systems MBr 4 ( M=C, Si, Ge). The EXAFS analysis by means of the cumulant expansion technique enables one to obtain information about force constants including the third-order anharmonicity. The second-order cumulants obtained experimentally are in excellent agreement with the values expected by the vibrational data and the third-order cumulants have been determined successfully. For the first nearest neighbor (NN) Br–M shells the stretching motions are apparently dominant to describe EXAFS, while for the second NN Br–Br shell the bending modes are found to contribute significantly to the cumulants especially for the third-order anharmonicity. The obtained force constants are compared to each other and the origin of observed bending anharmonicity is discussed.