报告题目：Low energy electron diffraction from modulated surfaces

报 告 人：Wolfgang Moritz  教授（University of  Munich）

主    办：天游线路检测中心、激光研究所

时    间：2017年5月15日 下午3：00

地    点：物理楼313报告厅

报告摘要：

Modulated surfaces occur frequently in adsorbate layers as well as on clean metal surfaces. Different mechanisms may explain the occurrence of surface modulations. Of actual interest are graphene layers on single crystal surfaces where the lattice mismatch and the interaction strength of C with the substrate determine the surface modulation. The electronic properties of graphene layers are strongly influenced by the interaction with the substrate and a detailed knowledge of the adsorption geometry is required to understand the interaction. In STM images the Moiré pattern are observed from which the orientation of the graphene lattice and the lattice constants can be determined. For quantitative structure analyses a description of the modulation functions is required. Symmetry restrictions in 2-D modulated lattices are shortly discussed. LEED-I(V) analyses of graphene layers are rare due to the large unit cells of the modulated structure. Two examples of structure analyses for graphene mono-layers on Ru(0001) and Ir(111) are shown and the results are compared to X-ray diffraction studies and DFT calculations.