Direct Methods for Surface Crystallography

虽然电子衍射技术已经成功地揭示了许多固体表面的详细结构，但早期的试错方法在应用于日益复杂的表面结构和成分方面受到限制。PI提出了基于全息方法的改进直接算法的发展，用于分析电子衍射实验结果。计划与威斯康星-密尔沃基大学和埃尔兰根-纽伦堡大学的研究人员合作进行实验工作，包括光电子全息术、低能电子衍射、反射和透射高能电子衍射。与慕尼黑大学的实验工作合作，计划开发表面x射线衍射的直接算法，以确定表面层的整个三维电荷密度。就像光学全息术可以产生物体的三维图像一样，从表面散射的电子束可以用来产生材料表面原子及其伴随的电子电荷密度的全息图像。这项研究计划的目标是开发更好的数学算法，将实验数据解码成这样的图像，并计划与使用各种电子散射技术的实验人员合作。这些方法对于基础研究很重要，但对于从催化到腐蚀等表面关键应用尤为重要

9815092SaldinAlthough electron diffraction techniques have been successful at revealing many of the detailed structures of solid surfaces, earlier trial-and-error approaches are limited in their application to increasingly complex surface structures and compositions. The PI proposes the development of improved direct algorithms based on a holographic approach for analyzing electron diffraction experimental results. Collaboration with experimental efforts are planned involving photoelectron holography, low energy electron diffraction, and reflection and transmission high energy electron diffraction with researchers from Wisconsin-Milwaukee and the University of Erlangen-Nuernberg. Additional work is planned in the development of direct algorithms for surface xray diffraction to determine the entire three-dimensional charge density of the surface layers, collaborating with experimental work at the University of Munich.%%%Much like optical holography can generate three-dimensional images of objects, electron beams scattered from surfaces can be used to generate holographic images of atoms and their accompanying electron charge densities at the surfaces of materials. The object of this research proposal is to develop better mathematical algorithms for decoding experimental data into such images, and collaborative work with experimentalists using a variety of electron scattering techniques is planned. These methods are important for basic research, but are particularly important for surface-critical applications ranging from catalysis to corrosion.***