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.

本研究的目的是开发一种新的光散射系统来检测时间分辨率为 1 ms 的波纹传播。 Ripplon 是一种热激发表面张力波，其传播提供了有关液体表面分子动力学的信息，例如表面活性剂的吸附过程和 Langmuir 薄膜的二维相变。作为研究结果，我们可以显着地通过引入高相干激光以及精细化的光学外差干涉仪，提高了检测的灵敏度。对于纯水波纹，测量的较高频率限制增加至 50 MHz，这是光散射的几何极限。然后将该系统应用于波纹的快速测量，通过长记忆数字示波器检测并记录波纹引起的光学跳动信号，并计算随机表面运动的相关函数。 1 ms数据采集时间内测量精度优于波纹频率1 %和阻尼5 %。该系统可用于典型钠表面活性剂动态吸附过程的测量肉豆蔻酸和我们可以成功地观察到清洁表面后表面张力随时间的变化。用分子扩散模型检查了表面恢复的行为，我们发现表面能势在确定表面形成的时间常数方面也起着重要作用。我们还观察到了表面电位的振荡现象。