High Resolution Low Energy Electron Diffraction Studies of Surface and Overlayer Ordering

表面和覆盖层排序的高分辨率低能电子衍射研究

• 批准号: 8906003
• 负责人: Gwo-Ching Wang
• 金额: $ 19.8万
• 依托单位: Rensselaer Polytechnic Institute
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-11-15 至 1993-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8906003&HistoricalAwards=false
• 关键词: Resolution; Low; Energy; Electron; Diffraction

The fundamental physical laws that govern the equilibrium and non-equilibrium collective phenomena of a clean surface near the melting temperature, and of an adsorbed overlayer will be investigated using the high resolution low-energy electron diffraction technique (HRLEED). They propose to study the change of structural and thermodynamic properties of clean metal surfaces during surface roughening/melting using HRLEED. Research efforts will include: (1) identification of the nature of the disorder and measurement of the density of defects generated at the surface near the melting temperature; (2) measurement of the short range correlations and critical exponents associated with the surface roughening/melting phase transition. For an adsorbed overlayer, research efforts will include (1) quantitative determination of overlayer domain growth during the relaxation of statistical mechanical states far from equilibrium; (2) testing of 2-D kinetic scaling theory and universality for an overlayer with ground state degeneracy greater than two; and (3) effects of impurities (random fields) on 2-D phase transitions and domain growth of a system with ground state degeneracy greater than two. The results of this research will not only help us gain insight into the fundamental power, scaling and growth laws which describe the clean surface and adsorbed overlayer ordering, but will also increase our knowledge in controlling important practical processes such as crystal growth and heterogeneous catalysis.

用高分辨低能电子衍射技术(HRLEED)研究了在熔化温度附近清洁表面和吸附覆盖层的平衡和非平衡集体现象的基本物理规律。他们建议使用HRLEED研究清洁金属表面在表面粗化/熔化过程中结构和热力学性质的变化。研究工作将包括：(1)识别无序的性质和测量熔化温度附近表面产生的缺陷密度；(2)测量与表面粗化/熔化相变相关的短程关联和临界指数。对于吸附的覆盖层，研究工作将包括：(1)定量确定远离平衡的统计力学状态松弛过程中的覆盖层的磁畴增长：(2)检验二维动力学标度理论和基态简并大于2的覆盖层的普适性；以及(3)杂质(随机场)对基态简并大于2的系统的二维相变和磁畴增长的影响。这项研究的结果不仅有助于我们深入了解描述清洁表面和吸附覆盖层有序化的基本幂、尺度和生长规律，而且还将增加我们在控制晶体生长和多相催化等重要实际过程方面的知识。