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Development ofinstrument for analysis of surface tension using radiation pressure of light

利用光辐射压分析表面张力的仪器的开发

基本信息

批准号：
18350012
负责人：
SAITOW Ken-ichi
金额：
$ 6.84万
依托单位：
Hiroshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18350012/
关键词：
radiation pressure surface tension critical point supercritical fluid

项目摘要

Matters obtain the momentum when the irradiate light is scatted by matters. This momentum is called radiation pressure of light. In the present study, we develop the instrument to evaluate surface tension using radiation pressure. In particular, vapor-liquid surface at around vapor-liquid critical point is very sensitive to perturbations. Such a sensitive interface or surface will be deformed by the radiation pressure of light, and the degree of deformation will be used to evaluate the surface tension.We have developed the instrument to construct optical cell for high-pressure condition, optics, and detection system. Windows of the cell was made of sapphire. Temperature was controlled by a set of a ND controller, heaters, and a thermocouple, and its fluctuation was within 0.1 degree. Pressure was monitored by a strain gauge. Important points for the present study are in the following. i) interface and/or surface should be observed at 90 degree against incident laser at high pressure condition, ii) laser has good TEM_<00> mode, iii) laser output is variable and its power is greater than 5W. By using laser, optics, and cell, we can develop the system to observe vapor-liquid interface at around vapor-liquid critical point. However, a problem happens. That is, the laser incidence generates babbles in fluid, which disturb the observation of interface. Since the laser wavelength is 532 nm, the laser light is not absorbed by CO_2, because CO_2 dose not have absorption band of electronic transition in visible region. It seems that these babbles are generated by energy transfer from laser to fluid via inelastic scattering such as Raman scattering. As a result, the fluid heated by transferred energy most probably generates bubbles. We tried to diminish the bubble by changing the fluid temperature, but the situation was not changed. In near future, further changes of thermodynamic states and/or the use of Raman no active fluid will be needed to overcome this bubble problem.

当照射的光被物质散射时，物质获得动量。这种动量称为光的辐射压。本研究中，我们研制了一种利用辐射压测量表面张力的仪器。特别是汽液临界点附近的汽液界面对扰动非常敏感。这样的敏感界面或表面会在光的辐射压力下发生形变，形变的程度将被用来评估表面张力。我们已经开发了用于构建高压条件下的光学池、光学和检测系统的仪器。牢房的窗户是用蓝宝石做的。温度由一组ND控制器、加热器和热电偶控制，其波动在0.1度以内。通过应变计监测压力。本研究报告的要点如下。i）在高压条件下，应在与入射激光成90度角处观察界面和/或表面，ii）激光具有良好TEM_<00>模式，iii）激光输出是可变的且其功率大于5 W。利用激光、光学和细胞等技术，我们可以发展一套在汽液临界点附近观察汽液界面的系统。然而，问题出现了。即激光入射时在流体中产生的气泡干扰了界面的观察。由于激光波长为532 nm，CO_2在可见光区没有电子跃迁的吸收带，所以激光不被CO_2吸收。这些气泡似乎是由能量通过非弹性散射（例如拉曼散射）从激光传递到流体而产生的。结果，被传递的能量加热的流体很可能产生气泡。我们试图通过改变流体温度来减少气泡，但情况没有改变。在不久的将来，将需要进一步改变热力学状态和/或使用拉曼无活性流体来克服这种气泡问题。