论文标题
大量X射线衍射数据的高分辨率表面结构测定
High-resolution surface structure determination from bulk X-ray diffraction data
论文作者
论文摘要
大多数表面现象的关键在于表面结构。特别是在表面上的电荷密度分布主要控制材料与外部环境的总体相互作用。人们普遍认为，表面结构不能从常规的散装X射线衍射数据中解密。因此，当我们打算特别描绘表面结构时，从技术上讲，我们被迫诉诸表面敏感技术，例如高能表面X射线衍射（HESXD），低能电子衍射（LEED），扫描透射传输电子显微镜（stem）和放牧的小角度X射线散射（Gisaxs）。在这项工作中，使用不同分子和扩展固体中晶体结构的非球荷电荷密度模型，我们显示了一种方便且互补的方法，用于确定来自常规的散装X射线衍射（XRD）数据的高分辨率实验表面电荷密度分布。我们方法的有用性已在碳化物的表面功能上得到验证。虽然碳化氢硼中的某些表面显示出大量电子缺陷中心的存在，但在其他情况下则存在。此后，已经确定了计算出的表面结构与相应功能特性之间的合理相关性。
The key to most surface phenomenon lies with the surface structure. Particularly it is the charge density distribution over surface that primarily controls overall interaction of the material with external environment. It is generally accepted that surface structure cannot be deciphered from conventional bulk X-ray diffraction data. Thus, when we intend to delineate the surface structure in particular, we are technically compelled to resort to surface sensitive techniques like High Energy Surface X-ray Diffraction (HESXD), Low Energy Electron Diffraction (LEED), Scanning Transmission Electron Microscopy (STEM) and Grazing Incidence Small Angle X-ray Scattering (GISAXS). In this work, using aspherical charge density models of crystal structures in different molecular and extended solids, we show a convenient and complementary way of determining high-resolution experimental surface charge density distribution from conventional bulk X-ray diffraction (XRD) data. The usefulness of our method has been validated on surface functionality of boron carbide. While certain surfaces in boron carbide show presence of substantial electron deficient centers, it is absent in others. Henceforth, a plausible correlation between the calculated surface structures and corresponding functional property has been identified.
