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Raman-scattering intensity and space luctuation of number density of molecules in amorphous molecular systems

非晶分子系统中分子数密度的拉曼散射强度和空间波动

基本信息

批准号：
07454156
负责人：
ISHII Kikujiro
金额：
$ 4.22万
依托单位：
Gakushuin University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07454156/
关键词：
amorphous Raman scattering light scattering density fluctuation crystallization crystal growth

项目摘要

This work was carried out to confirm experimentally that the Raman-scattering intensity from amorphous systems is weakened by the space fluctuation of the polarizability of the sample, and thus to indicate that Raman scattering is the interfering light scattering. In the first year, a high-vacuum chamber was designed and constructed for preparing amorphous molecular films with a good structural reproducibility, and also a high-sensitivity optical system was assmbled for the Raman measurement. Then, experiments were carried out to compare the light intensities scatted from the molecular film by the elastic-scttering due to the unhomogeneity in the sample and by the Raman process. Results of these experiments suggested that the molar-intensity of Raman scattering from crystalline molecular grain might depend on te grain size and thus on the correlation function of the polarizability of the sample.In the second year, experiments were carried out for investigating the optical properties of amorphous molecular films during their preparation by the vacuum deposition on cold substrates. Light interference in the films was monitored, and was compared with the results of theoretical simulation. It was found that the amorphous films prepared at relatively high temperatures are transparent and homogeneous, but those prepared at very low temperatures tend to grow unhomogeneity in the film during the deposition. From the results of X-ray diffraction, which was carried out separately, the size of crystalline grain appearing by the annealing of the amorphous films thus prepared are 30-40 nm. Therefore, the characteristic length of the density fluctuation in the amorphous films prepared at very low temperatures are inferred to be the order of several tens of nanometer, and such unhomogeneity in the sample might be the cause of the small intensity of Raman scattering from amorphous systems. Detailed examination of the experimental results will be continued in future.

这项工作是为了从实验上证实非晶态体系的拉曼散射强度被样品的偏振度的空间涨落所削弱，从而表明拉曼散射是干涉光散射。第一年，为制备具有良好结构重现性的非晶态分子薄膜，设计并建造了高真空室，并配备了高灵敏度的光学系统用于拉曼测量。然后，实验比较了由于样品中的不均匀而由弹性溅射和拉曼过程得到的分子膜的散射光强度。这些实验结果表明，晶态分子颗粒的拉曼散射的摩尔强度可能依赖于晶体颗粒的尺寸，从而取决于样品的极化率的关联函数。第二年，我们进行了实验，研究了非晶分子薄膜在冷衬底上真空沉积制备过程中的光学性质。对薄膜中的光干涉进行了监测，并与理论模拟结果进行了比较。研究发现，在较高温度下制备的非晶薄膜是透明且均匀的，但在极低温度下制备的薄膜在沉积过程中容易出现不均匀现象。从分别进行的X射线衍射结果来看，所制备的非晶膜在热处理过程中出现的晶粒度为30-40 nm。由此推测，在极低温度下制备的非晶态薄膜的密度起伏特征长度为几十纳米量级，这种不均匀性可能是非晶态体系拉曼散射强度较小的原因。未来将继续对实验结果进行详细审查。