RUI: Structural Evolution of Bimetallic Deposition Systems

9974545 roelofs本科院校研究（RUI）奖支持探索异质外延沉积体系演变的理论研究。对于许多系统来说，同外延生长系统现在已经很好地理解了，因此，面对双金属系统的挑战是全面理解外延生长现象的下一个自然步骤。双金属体系包含了表面合金体系，并且与表面磁性和催化具有重要的相关性，这是推动这一进展的强大技术动机。最近，PI模拟了一个典型的双金属外延系统，在Ag（001）表面沉积了亚单层数量的Rh。广泛的扫描隧道显微镜（STM）结果显示了该系统的几个不寻常的结构特征，最明显的是在银衬底上出现了孔。PI已经开发了一个模型，用于在原子水平上处理这种系统和类似系统的表面动力学，换句话说，是对产生所见结构的原子尺度运动的详细描述。该模型基于控制局部原子排列的能量势垒的简单但物理上合理的近似，它构成了一个强大的模拟程序的基础，该程序生成并表征了所得到的表面特征的演变。这种方法已经成功地定性地说明了Rh/Ag（001）系统中所看到的有趣结构，并且最近提交了第一份报告供发表。目前的工作将扩展这种治疗方法，并与德国乌尔姆的Behm实验组合作建立其他制度和系统的模型。Behm的团队在研究双金属生长系统方面具有广泛的实验能力，实际上是Rh/Ag（001）系统的大部分STM数据的来源。需要进一步完善我们的Rh/Ag（001）系统模型，并将其扩展到多层情况和其他温度状态。该模型将应用于其他双金属生长系统，包括一些与催化相关的系统。我们还能够在空位和附着原子在复杂表面结构的形成和重排中的作用方面产生重要的基础结果。本科院校研究（RUI）奖支持探索异质外延沉积系统演变的理论研究。对于许多系统来说，同外延生长系统现在已经很好地理解了，因此，面对双金属系统的挑战是全面理解外延生长现象的下一个自然步骤。双金属体系包含了表面合金体系，并且与表面磁性和催化具有重要的相关性，这是推动这一进展的强大技术动机。理论工作将与德国的一个实验小组合作完成。

9974545RoelofsThis Research at Undergraduate Institutions (RUI) award supports theoretical research to explore the evolution of heteroepitaxial, deposition systems. Homoepitaxial growth systems are now reasonably well understood for many systems so that coming to terms with the challenges of bi-metallic systems is the next natural step toward a full understanding of epitaxial growth phenomena. There is a strong technological motivation for such progress in that bi-metallic systems encompass surface alloy systems and also have important relevance for surface magnetism and catalysis. Recently the PI has modeled a prototypical bi-metallic, epitaxial system, the deposition of submonolayer amounts of Rh on the Ag(001) surface. Extensive scanning tunneling microscopy (STM) results are available for this system and these display several unusual structural features, most notably the occurrence of holes in the silver substrate. The PI has developed a model for treating the surface kinetics of this and similar systems at the atomic level, a detailed account, in other words, for the atomic scale movements that occur to produce the structures seen. The model is based on a simple, but physically reasonable approximation for the energy barriers governing local atomic arrangement, which forms the basis of a powerful simulation program which generates and characterizes the evolution of the resulting surface features. This approach has already succeeded in qualitatively accounting for the interesting structures seen for the Rh/Ag(001) system, and a first report has recently been submitted for publication. The present work will extend this treatment and model other regimes and systems in collaboration with the experimental group of Behm in Ulm, Germany. Behm's group has extensive experimental capability for study of bi-metallic growth systems an is in fact the source of much of the STM data for the Rh/Ag(001) system. Further refinement of our model for the Rh/Ag(001) system is needed and it will be extended to the multi-layer case and to other temperature regimes. The modeling will be applied to other bi-metallic growth systems, including some with catalytic relevance. We are also capable of producing important fundamental results on the role of vacancies and adatoms in the formation and rearrangement of complex surface structures.This Research at Undergraduate Institutions (RUI) award supports theoretical research to explore the evolution of heteroepitaxial, deposition systems. Homoepitaxial growth systems are now reasonably well understood for many systems so that coming to terms with the challenges of bi-metallic systems is the next natural step toward a full understanding of epitaxial growth phenomena. There is a strong technological motivation for such progress in that bi-metallic systems encompass surface alloy systems and also have important relevance for surface magnetism and catalysis. The theoretical work will be done in collaboration with an experimental group in Germany.