Electron Spectroscopic Studies of the Electronic and Geometric Structure of, and Chemisorption on, Transition Metal Oxide Surfaces

在过去的几年里，耶鲁大学的表面科学实验室已经成为世界上研究氧化物表面基本性质的最重要的研究中心。Henrich教授的方法是使用在超高真空环境或受控化学吸附条件下制备和研究的单晶样品，并使用广泛的表面敏感电子光谱技术测量其几何和电子结构。过渡金属氧化物是催化和表面化学中最重要的金属氧化物，根据其配位环境的不同，过渡金属氧化物的阳离子可以有几种不同的价态。在近乎完美的真空解理表面上进行测量是必要的起点，特别是在与理论计算进行比较时。然而，他的主要兴趣在于表面缺陷的性质及其与吸附分子的相互作用。表面缺陷已被证明是几乎所有已研究的氧化物上化学吸附的活性位置，近乎完美的表面相对惰性。亨利克教授在这里提出了一个为期三年的研究计划，包括继续目前正在进行的最有成效的研究领域，以及几个新的方向，这些新方向将解决一些迄今为止研究尚未回答的重要问题。我们将用反向光电子能谱研究氧化物表面的空电子态，并用新获得的高分辨率电子能量损失谱来研究催化活性分子与氧化物相互作用的微妙之处。与IBM沃森研究中心的一项合作将使用扫描隧道显微镜来确定完美和缺陷氧化物表面的几何形状，并测量其填充和空电子能级的光谱。

During the past few years the Surface Science Laboratory at Yale has become established as the world's foremost research center for the study of the fundamental properties of oxide surfaces. Professor Henrich's approach is to use single crystal samples, prepared and studied in an ultrahigh vacuum environment or under controlled chemisorption conditions, and to measure their geometric and electronic structure by using a wide range of surface sensitive electron spectroscopic techniques. Particular attention has been given to the transition metal oxides, whose cations can have any of several different valence states depending upon their ligand environment; these oxides are the most important ones in catalysis and surface chemistry. Measurements on nearly perfect, vacuum cleaved surfaces are a necessary starting point, particularly for comparison with theoretical calculations. However, his primary interest is in the properties of surface defects and their interaction with adsorbed molecules. Surface defects have been shown to be the active sites for chemisorption on almost all oxides that have been studied, with nearly perfect surfaces being relatively inert. Professor Henrich proposes here a three-year research program consisting both of a continuation of the most productive research areas that are currently being pursued and of several new directions that will address some of the important questions that research to date has left unanswered. Empty electronic states on oxide surfaces will be examined by using inverse photoelectron spectroscopy, and a newly acquired high resolution electron energy loss spectrometer will be used to study the subtleties of the interaction of molecules of catalytic interest with oxides. A collaborative effort with the IBM Watson Research Center will use scanning tunneling microscopy to determine the geometry of both perfect and defect oxide surfaces and to measure the spectra of their filled and empty electronic levels.