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Phase transitions between 2-and 3-dimensions in rare gas thin films on a surface of a metal single crystal.

金属单晶表面稀有气体薄膜中二维和三维之间的相变。

基本信息

批准号：
05452105
负责人：
ARAKAWA Ichiro
金额：
$ 1.73万
依托单位：
Gakushuin University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05452105/
关键词：
Ellipsometry Physisorption Multi-layr adsorption Rare gas thin film 2-d phase transition 2-d 3-d phase transition Wetting transition 物理吸着層相転移

项目摘要

We have developed the new experimental equipment for ellipsometric studies of physisorption system, which can be operated under ultra-high vacuum and low temperature environment. Extremely high vacuum as low as 10^<-9> Pa is achieved without experimental components and the range of 10^<-8> Pa under experimental conditions. A platinum single crystal, on which rare gas is physisorbed, is mounted on a helium gas flow type cryostat that was designed and developed in this project. The ellipsometer system with automatic null method by PID controller was developed.We have found the enough traceability of the automatic null ellipsometer for the change of surface conditions during the cleaning process, ion bombardment and annealing, of the surface. The adsorption isotherm of Xe/Pt (111) at temperatures above the triple-point of Xe was obtained in the wide pressure range between 10^<-7> Pa and 10^<-2> Pa. The above-mentioned properties of our ellipsometer system makes it possible to observe layr … More growth from a submonolayr to thick layr where equilibrium pressure is nearly equal to the bulk saturation vapor pressure.The present experimental problem is temperature measurement. A Pt vs.Pt+Rh thermocouple is attached to the Pt crystal because of its durability at a high temperature during the annealing process. However, the relatively low thermoelectric power of the thermocouple in a low temperature range makes it difficult to measure a precise temperature in the adsorption experiment. We are preparing an alternative method : a combination of a Pt resistance thermometer and thermocouple.We are proceeding the measurement of a phase diagram of several adsorbent-adsorbate systems, Ne, Ar, Kr, Xe, and CH_4 on Pt (111), Ag (111), etc. for example. The obtained adsorption isotherms will be compared in the term of a relative temperature to the triple point or the critical point, a relative pressure to the saturation vapor pressure, a ratio between the lattice parameters, etc. From these results, we will deduce empirical laws of 2d-3d and wetting transition, surface roughening and melting, etc. On the basis of these observations, we will finally discuss the theoretical model of these surface phenomena. Less

我们研制了可在超高真空、低温环境下工作的物理吸附体系椭圆偏振测量实验装置。在没有实验元件的情况下，获得了低至10^&lt；-9&gt；pa的极高真空，在实验条件下达到了10^&lt；-8&gt；pa的范围。将物理吸附稀有气体的铂单晶安装在本项目设计开发的氦气流动型低温恒温器上。研制了基于PID控制器的自动归零法椭偏仪系统，发现自动归零椭偏仪对表面清洗、离子轰击、退火等过程中的表面状态变化具有足够的溯源能力。在10^&lt；-7&gt；pa和10^&lt；-2&gt；pa之间的较宽压力范围内，获得了Xe/Pt(111)在Xe三点以上的吸附等温线。我们的椭偏仪系统的上述特性使观测Layr…成为可能从亚单分子层到厚层的更多生长，其中平衡压力几乎等于整体饱和蒸汽压。目前的实验问题是温度测量。铂与铂+Rh热电偶附着在铂晶体上，因为它在热处理过程中在高温下耐用。然而，在吸附实验中，由于热电偶在低温范围内的热电功率相对较低，因此很难精确测量温度。我们正在准备一种替代的方法：铂电阻温度计和热电偶的组合。我们正在进行几个吸附-吸附体系的相图的测量，例如，Ne，Ar，Kr，Xe，和CH_4在铂(111)，银(111)等上的相图。将得到的吸附等温线与三相点或临界点的相对温度、相对压力与饱和蒸汽压、晶格参数之间的比值等进行比较，由此我们将推导出二维-三维与润湿转变、表面粗糙和熔化等的经验规律。在此基础上，我们将讨论这些表面现象的理论模型。较少