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Development of rapid ripplon spectroscopy and its application to liquid surface physics

快速波纹谱的发展及其在液体表面物理中的应用

基本信息

批准号：
15360035
负责人：
SAKAI Keiji
金额：
$ 9.92万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15360035/
关键词：
Ripplon Surface active agents Langmuir films Surface phase transition Dynamic Light Scattering Real-time measurement Molecular adsorption

项目摘要

The purpose of this study is to develop a new light scattering system to detect the ripplon propagation with the time resolution of 1 ms. Ripplon is a thermally excited surface tension wave, whose propagation gives information on the molecular dynamics on the liquid surface, such as the adsorption process of surfactants and the two-dimensional phase transition of Langmuir films.As the result of the study, we could remarkably improve the sensitivity of the detection by introducing the highly coherent laser as well as the refined optical heterodyne interferometer. The higher frequency limit of the measurement was increased up to 50 MHz for the ripplon on pure water, which is the geometric limit of the light scattering. The system was then applied for the rapid measurement of the ripplon, in which the optical beating signal due to the ripplon is detected and recorded by the digital oscilloscope with long memory and the correlation function of the random surface motion is calculated. The accuracy of the measurement during the data acquisition time of 1 ms is better than 1 % for ripplon frequency and 5 % for the damping.The system is then applied for the measurement of the dynamic adsorption process of the typical surface-active agents of sodium myristic acid and we could successfully observed the temporal change of the surface tension after the cleaning the surface. The behavior of the surface recovery is examined with the model of the molecular diffusion and we found that the surface energy potential also plays an important role to determine the time constant of the surface formation. We also observed the oscillatory phenomenon of surface potential.

本研究的目的是发展一种新的光散射系统来检测ripplon的传播，其时间分辨率为1 ms。Ripplon是一种热激发的表面张力波，其传播提供了液体表面分子动力学的信息，如表面活性剂的吸附过程和Langmuir膜的二维相变。作为研究的结果，通过引入高相干激光和精密的光外差干涉仪，可以显著提高检测的灵敏度。对于纯水上的ripplon，测量的较高频率极限增加到50 MHz，这是光散射的几何极限。利用该系统对波纹子进行了快速测量，利用具有长存储功能的数字示波器检测并记录波纹子产生的光学拍频信号，并计算出随机表面运动的相关函数。在1ms的数据采集时间内，测量精度优于1%的纹波频率和5%的阻尼.然后将该系统应用于测量典型的表面活性剂肉豆蔻酸钠的动态吸附过程中，我们可以成功地观察到表面张力的时间变化后，表面清洁.表面恢复的行为与分子扩散的模型进行了检查，我们发现，表面能势也起着重要的作用，以确定表面形成的时间常数。我们还观察到了表面电位的振荡现象。