Dynamic Observation of Outermost Surface Layer Reactions by Metastable Electron Emission Microscope

在这项研究中，我们试图观察分子的吸附和扩散，以及分子之间的二维反应的动态过程在一个明确的固体表面上，使用亚稳电子发射显微镜（MEEM）在我们实验室最近开发的。该显微镜利用电子透镜系统对亚稳原子撞击固体表面发出的电子进行成像。研究结果如下：(1)将COD摄像机直接连接到MAES仪器的MCP检测部分。新的数据分析系统与摄像机相结合，通过对图像的处理，使我们能够灵敏地观察到MEEM图像。(2)加热清洗衬底（硅单晶表面、石墨和二硫化钼晶体解理面、金刚石薄膜等）。利用LEED（低能电子衍射）、EELS（电子能量损失谱）和MAES（亚稳原子电子能谱）对清洗过程进行了观察。(3)采用真空升华法制备了酞菁、PTCDA（苝-四羧酸二酐）等有机化合物样品。利用MEEM（微局部和能量滤波图像）和LEEM（微局部和能量滤波图像）观察薄膜随时间的变化和分子的扩散过程。(4)在普通表面分析仪器上，用Penning电离电子能谱（PIES）、角度分辨紫外光电子能谱（ARUPS）和高分辨率电子能量损失能谱（HREELS）进行了类似的观察。(5)在衬底上沉积两种样品（有机化合物和金属如In）。观察了样品间的二维反应。(6)在上述结果的基础上，澄清了反应速率、反应在分子中的位置以及电子态变化中的动力学过程。少

In this study we tried to observe the adsorption and diffusion of molecules, and dynamic processes of two-dimensional reactions between molecules on a well-defined solid surface, using the metastable electron emission microscope (MEEM) recently developed at our laboratory. This microscope images electrons emitted from the solid surface by impact of metastable atoms by means of an electron lens system. The results of the study are as follows.(1) A COD camera was directly connected to the MCP detection part of the MAES apparatus. A new data analysis system combined with the camera enabled us to observe MEEM images sensitively by processing the images.(2) Substrates (surfaces of silicon single crystals, cleavage planes of graphite and MoS_2 crystals, diamond films, etc.) were cleaned by heating. The process of the cleaning was observed by LEED (low energy electron diffraction), EELS (electron energy loss spectroscopy) and MAES (metastable atom electron spectroscopy).(3) The samples of org … More anic compounds (phthalocyanines, PTCDA (perylene-tetracarboxy1ic- dianhydride), etc.) were deposited by vacuum sublimation onto the above substrates. The change of the films with the elapse of time and the diffusion process of molecules were observed by MEEM (giving PIES in the micro-local area and energy-filtered images) and LEEM (giving EELS in the micro-local area and energy-filtered images).(4) The similar observations as above were carried out by PIES (Penning ionization electron spectroscopy), ARUPS (angle-resolved ultraviolet photoelectron spectroscopy), and HREELS (high-resolution electron energy loss spectroscopy) on ordinary surface-analysis apparatuses.(5) Samples of two kinds (organic compound and metal such as In) were deposited onto the substrates. The two-dimensional reactions between the samples were observed.(6) On the basis of the above results, the reaction rate, the position of the reaction in the molecule, and dynamic process in the change of the electronic state were clarified. Less