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The study of disordered phases on solid surfaces by diffuse low-energy electron diffraction

弥散低能电子衍射研究固体表面无序相

基本信息

批准号：
07650030
负责人：
SAKAMA Hiroshi
金额：
$ 1.66万
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 (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07650030/
关键词：
low-energy electron diffraction diffuse scattering disorder 低速電子回析

项目摘要

The system of measuring the intensity distribution diffuse LEED images was developed. LEED images on the fluorescent screen of four-grid type LEED apparatus were taken with a CCD camera, digitized and stored with an A/D converter and a 16-bit buffer memory. Noises from the CCD camera were highly suppressed by cooling CCD devise with water. Consequently, the intensities of very weak incoherently-scattered beams were able to be measured correctly as well as those of normal coherent beams. Intensity vs. voltage (I-V) curves were evaluated using a specific software from memorized intensity data.The diffuse LEED images from disordered Cu (100) pseudo-c (2*2)-O phase were measured with this system. The coverage of oxygen on the Cu (100) surface was estimated to be about 0.1 monolayrs. Oxygen was adsorbed on the surface at low temperature (110K), followed by the post annealing of the surface at 300K.The measurement was also performed at 110K.Noise due to lattice vibrations of surface atoms were eliminated by the subtraction of a LEED image of clean surface from that of the disordered surface. The intensity of a fixed on the LEED image was measured by an integration of intensities within a square electric window. Using a trial-and-error approach, it was shown that the side of the electric window must be smaller than 1/3 of the basic reciprocal lattice vector of clean surface. After the procedure, I-V curves with a high degree of accuracy were successfully obtained from the disordered Cu (100) pseudo-c (2*2) -O phase.

开发了漫射 LEED 图像强度分布测量系统。四栅格型LEED设备荧光屏上的LEED图像是用CCD相机拍摄的，通过A/D转换器和16位缓冲存储器进行数字化和存储。通过用水冷却 CCD 装置，可以高度抑制 CCD 相机发出的噪声。因此，非常弱的非相干散射光束的强度以及正常相干光束的强度都能够被正确测量。使用特定软件根据记忆的强度数据评估强度与电压 (I-V) 曲线。使用该系统测量无序 Cu (100) 伪 c (2*2)-O 相的漫射 LEED 图像。 Cu(100)表面上氧的覆盖率估计为约0.1单层。在低温（110K）下，氧被吸附在表面上，然后在 300K 下对表面进行后退火。测量也在 110K 下进行。通过从无序表面的 LEED 图像中减去干净表面的 LEED 图像，消除了由于表面原子晶格振动引起的噪声。 LEED 图像上的固定强度是通过方形电动窗口内的强度积分来测量的。通过反复试验的方法表明，电动车窗的边长必须小于洁净表面基本倒易格向量的1/3。在此过程之后，成功地从无序的Cu(100)伪c(2*2)-O相中获得了高精度的I-V曲线。