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Direct observation of static and dynamic fluctuations in two-dimensional fluid mercury

直接观察二维流体汞的静态和动态涨落

基本信息

批准号：
14340106
负责人：
YAO Makoto
金额：
$ 9.47万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14340106/
关键词：
mercury-sapphire interface wetting critical fluctuation prewetting transition thermal radiation intensity correlation length dynamic light scattering critical point 相関関数

项目摘要

It is well known that liquid mercury hardly wets non-metallic substances such as glasses or sapphire under ambient conditions. However, M.Yao (the head investigator of this project) found in 1996 that mercury wets sapphire substrate under high temperature and pressure conditions near the liquid-gas critical point (1478℃, 167MPa), and that the thickness of the wetting film jumps discontinuously at a line on the pressure-temperature plane. This is the 1st order phase transition called the prewetting transition. In the present work, we studied the static and dynamic fluctuations in the mercury wetting film on the sapphire substrate near the prewetting critical point for the first time in the world.We observed the static fluctuations at the interface by measuring the thermal radiation intensity. This method is based on the fact that the thermal radiation intensity contains information on the reflectivity and the diffuse scattering cross section at the interface of the sample (Kirchhoff's l … More aw). We deduced successfully the fluctuation of the wetting film from the observed thermal radiation intensity. In this measurement, a new collimator system was employed to eliminate the contribution from the materials near the sample. We found that the lateral correlation length of the critical fluctuations is several hundred manometers, which is much larger than the thickness of the wetting film (〜10nm).Next, we studied the dynamics of the prewetting critical phenomena by using dynamic light scattering techniques. The oscillatory component (frequency ω, damping ratio Γ) in the observed autocorrelation function strongly suggests that the light is scattered by the surface wave formed on the surface of the wetting film. When the pressure is decreased from the liquid-gas coexistence line to the prewetting line, both ω and Γ show rapid increase. Near the prewetting critical point, on the other hand, they decrease due to the critical slowing down. In this way, the direct observation of static and dynamic fluctuations in the two-dimensional fluid mercury has successfully been achieved in this project. Less

众所周知，在环境条件下，液态汞很难润湿玻璃或蓝宝石等非金属物质。然而，1996年，该项目的首席研究员姚明（M.Yao）发现，汞在液-气临界点（1478℃，167 MPa）附近的高温高压条件下润湿蓝宝石衬底，润湿膜的厚度在压力-温度平面上的一条线上不连续地跳跃。这是一阶相变，称为预润湿转变。本工作在国际上首次研究了蓝宝石衬底上汞润湿膜在预润湿临界点附近的静态和动态涨落，通过测量热辐射强度观察到界面处的静态涨落。该方法基于热辐射强度包含关于样品界面处的反射率和漫散射截面的信息（Kirchhoff's l ...更多信息 aw）。我们成功地从观测到的热辐射强度推断出润湿膜的涨落。在该测量中，采用新的准直器系统来消除来自样品附近的材料的贡献。我们发现临界涨落的横向相关长度为几百纳米，远大于润湿膜的厚度（约10 nm）。接下来，我们利用动态光散射技术研究了预润湿临界现象的动力学过程。观察到的自相关函数中的振荡分量（频率ω，阻尼比Γ）强烈地表明光被润湿膜表面上形成的表面波散射。当压力从气液共存线降低到预湿线时，ω和Γ都迅速增大。另一方面，在预湿临界点附近，它们由于临界减慢而减小。本项目成功地实现了对二维流体汞的静态和动态涨落的直接观测。少