Surface, subsurface and buried interface structure at the atomic scale; pushing the limits of medium energy ion scattering

原子尺度的表面、次表面和埋入界面结构；

• 批准号: EP/E021786/1
• 负责人: David Woodruff
• 金额: $ 45.05万
• 依托单位: University of Warwick
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FE021786%2F1
• 关键词: Surface; subsurface; buried; interface; structure

Solid surfaces are important in many practical situations, such as heterogeneous catalysis, corrosion and the way one solid bonds to another to make electronic devices. Often it is just the outermost one or two atomic layers of the solid which determine these properties, and over the last 30 years a range of specialised techniques have been developed which probe only these few layers and are not influenced by the underlying bulk solid for which a range of other analytical methods exist. Medium energy ion scattering (MEIS) is essentially unique in bridging the gap between these sets of methods; it can be used to probe only the outermost few atomic layers, but can also probe the subsurface up to a few hundred atomic layers below the surface. On these depth scales it can provide both compositional and structural information, and has the unusual advantage of being especially sensitive to how a solid surface may be modified by the presence of adsorbed atoms and molecules.This project seeks to exploit these special advantages, using the UK national MEIS facility at Daresbury, to investigate model systems which typify a number of different surface and near-surface systems and phenomena. One example is the problem of oxide surfaces, of great importance in heterogeneous catalysis but relatively unexplored, especially in terms of their surface structure. Ultra-thin oxide films on metals are especially relevant to their applications, and MEIS will be used to determine both the oxide surface and oxide/metal interface structure in specific systems, notably Pd(111)/V2O3. The reactivity of surfaces is known to often be strongly influenced by surface defects, such as atomic steps, yet detailed information on the structure of these steps and the way the atoms relax at the reduced coordination sites is lacking; MEIS investigations are planned to address this problem. The technique is also ideally suited to investigate distortions of a metal surface induced by adsorbed molecules, and it is proposed to exploit this to probe thiol/metal interfaces, in particular; these form the basis of many self-assembled monolayers, yet the interface structure is poorly understood. Finally, the combination of structural and compositional information provided by MEIS is of great value in studying the surface and near-surface properties of metal alloy surfaces and surface alloys, and specific model systems of this type are proposed for study, including systems of interest in magnetism.A further theme of the proposed research involves investigations of the fundamental physics of the MEIS technique itself, notably the nature of inelastic energy loss, which gives MEIS its depth resolution, and neutralisation, which influences the ion yields and thus the quantification. A better understanding of these processes should benefit the whole MEIS user community, allowing more detailed and more reliable information to be extracted from MEIS experiments.

固体表面在许多实际情况中都很重要，例如多相催化、腐蚀以及一种固体与另一种固体结合以制造电子设备的方式。通常，决定这些性质的只是固体最外面的一层或两层原子层，在过去的30年里，已经开发了一系列专门的技术，这些技术只探测这几层，不受底层散体固体的影响，对于这些物质，存在着一系列其他分析方法。中能离子散射(MEIS)在弥合这两种方法之间的差距方面基本上是独一无二的；它只能探测最外层的几个原子层，但也可以探测次表面以下多达几百个原子层。在这些深度尺度上，它可以提供成分和结构信息，并具有对固体表面如何通过吸附原子和分子的存在而改变特别敏感的不同寻常的优势。该项目试图利用这些特殊优势，利用位于达累斯伯里的英国国家MEIS设施，研究代表许多不同表面和近表面系统和现象的模型系统。一个例子是氧化物表面的问题，这在多相催化中非常重要，但相对来说还没有被探索，特别是就其表面结构而言。金属表面的超薄氧化物薄膜与它们的应用特别相关，MEI将被用来确定特定系统中的氧化物表面和氧化物/金属界面结构，特别是Pd(111)/V2O。众所周知，表面的反应性往往受到表面缺陷的强烈影响，如原子步骤，但缺乏关于这些步骤的结构和原子在还原配位处松弛方式的详细信息；计划进行MEIS调查以解决这一问题。该技术还非常适合于研究由吸附分子引起的金属表面的扭曲，特别是建议利用这一点来探测硫醇/金属界面；这些界面形成了许多自组装单分子膜的基础，但对界面结构的了解很少。最后，MEIS提供的结构和成分信息的结合对于研究金属合金表面和表面合金的表面和近表面性质是非常有价值的，并提出了这类特定的模型系统用于研究，包括感兴趣的磁学系统。建议的研究的另一个主题涉及MEIS技术本身的基本物理，特别是非弹性能量损失的性质，这使得MEIS具有深度分辨率，以及中和，它影响离子产额，从而影响量化。更好地了解这些过程将使整个MEIS用户群体受益，从而能够从MEIS实验中提取更详细和更可靠的信息。

项目成果

Medium energy ion scattering investigation of methylthiolate-induced modification of the Au(111) surface

甲硫醇诱导的 Au(111) 表面修饰的中能离子散射研究

• DOI: 10.1016/j.susc.2010.10.011
• 发表时间: 2011
• 期刊: Surface Science
• 影响因子: 1.9
• 作者: Sheppard D