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Study on the Interfacial Friction of Helium Films

氦膜界面摩擦研究

基本信息

批准号：
15540334
负责人：
SUZUKI Masaru
金额：
$ 2.3万
依托单位：
The University of Electro-Ccmmunications
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
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-15540334/
关键词：
Interfacial Friction Physisorbed Film Helium Film Graphite ヘリウム吸着

项目摘要

Friction is a common force, but is poorly understood from a microscopic point of view. Recently, experimental observations of an atomic-scale friction were reported using newly developed techniques, e.g., the atomic force microscope (AMF). And a peculiar friction nature has been observed.Thus motivated, we investigated the interfacial friction of helium films adsorbed on Grafoil (exfoliated graphite). In the present experiments, the quartz-crystal microbalance (QCM) technique was adopted for the measurement of this friction. In the technique, when the interfacial friction of the films is decreased and the film is decoupled from the lateral oscillation, an increase in the resonant frequency of the crystal is observed.We found that nonsuperfluid ^4He films partially decouple from the lateral oscillation, and the degree of decoupling increases below Ts. From the amplitude dependence of this increase, we showed that the frictional force between Grafoil substrate and ^4He film is almost proportional to the square root of the sliding velocity. However, the atomic mechanism of this nonlinear friction is still an open question. In addition, the increase in decoupling below Ts is closely related to the layer structure of ^4He film, making this a subject for future study.

摩擦力是一种常见的力，但从微观的角度来看，人们对它的理解却很少。最近，使用新开发的技术报道了原子尺度摩擦的实验观察，例如，原子力显微镜（AMF）在此基础上，我们研究了氦膜在膨胀石墨（Grafoil）表面的摩擦特性。在本实验中，采用石英晶体微天平（QCM）技术测量这种摩擦。在该技术中，当薄膜的界面摩擦减小，薄膜与横向振荡解耦时，晶体的共振频率增加，我们发现非超流^4He薄膜与横向振荡部分解耦，并且在Ts以下解耦程度增加。从这种增加的幅度依赖性，我们表明Grafoil衬底和^4He膜之间的摩擦力几乎与滑动速度的平方根成正比。然而，这种非线性摩擦的原子机制仍然是一个悬而未决的问题。此外，Ts以下去耦的增加与^4He膜的层结构密切相关，这使其成为未来研究的主题。