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Dynamics of Moiecular Glasses Studied by Using Partially Deuterated Systems

使用部分氘化系统研究分子玻璃动力学

基本信息

批准号：
10640369
负责人：
YAMAMURO Osamu
金额：
$ 2.11万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10640369/
关键词：
Neutron Scattering Glass Boson Peak Alcohol Hydrogen Bond Dynamic Structure Factor Deuteration 重水素置換

项目摘要

We have measured the inelastic neutron scattering (INS) of the glasses of some deuterated alcohols to investigate the microscopic mechanism of the boson peak. The measured samples are glassy propanols and glycerols selectively deuterated at hydroxyl and/or alkyl groups. The observed INS spectra are dominated by the vibrations of the parts with hydrogen atoms since incoherent scattering cross section of hydrogen atom is more than 10 times larger than those of other atoms. We used AGNES spectrometer belonging to Institute of Solid State Physics, the University of Tokyo. A boson peak appeared at around 2 meV in propanols and 3.5 meV in glycerols. The peak energy and intensity were not changed much by the deuterations for both alcohols. This indicates that the origin of the boson peak is the cooperative vibration of the hydrogen bond network (or chain) and alkyl parts. The present results qualitatively agreed with the broken network model recently developed by Nakayama.We have also performed the INS experiment of the glasses of potassium metaphospate deuterate (KPOィイD23ィエD2・0.70DィイD22ィエD2O). by using MARI spectrometer in Rutherford Appleton Laboratory, UK. The coherent INS spectrum showed that the boson observed at 3-4 meV in the incoherent spectrum is split into two peaks at 2.5 and 6 meV. This is a new finding probably related to the one dimensional network of the present material. We have also found the dispersive nature of the acoustic phonon in the scattering intensity map in the momentum vs energy transfer plane. The periodicity of the dispersion corresponded to that of static structure factor S (Q). This phenomenon may be related to the well-defined local structure of the network glass.

为了研究玻色子峰的微观机制，我们测量了一些氘化醇玻璃的非弹性中子散射（INS）。测量的样品是玻璃状的丙醇和甘油选择性地在羟基和/或烷基上氘化。由于氢原子的非相干散射截面比其他原子的非相干散射截面大10倍以上，因此观测到的INS光谱主要受氢原子部分的振动支配。我们使用的是东京大学固体物理研究所的AGNES光谱仪。在丙醇和甘油中，玻色子峰值分别在2mev和3.5 meV左右出现。两种醇的峰值能量和强度都不受氘化的影响。这表明玻色子峰的起源是氢键网络（或链）和烷基部分的协同振动。目前的结果与Nakayama最近提出的破碎网络模型在质量上是一致的。我们还对偏磷酸钾氘酸盐玻璃（KPO φ φ D23 φ φ D2·0.70 φ φ D22 φ D2O）进行了INS实验。利用英国卢瑟福阿普尔顿实验室的MARI光谱仪。相干INS谱表明，在非相干谱中观测到的3-4 meV的玻色子在2.5和6 meV处分裂为两个峰。这是一个新发现，可能与现有材料的一维网络有关。我们还发现了声子在动量-能量传递平面的散射强度图中的色散性质。色散的周期性与静态结构因子S (Q)的周期性相对应。这种现象可能与网状玻璃的局部结构明确有关。