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

在这项研究中，我们试图利用我们实验室最近发展起来的亚稳态电子发射显微镜(MeEM)来观察分子在定义良好的固体表面上的吸附和扩散，以及分子之间的二维反应的动态过程。这种显微镜通过电子透镜系统拍摄亚稳原子撞击固体表面发出的电子的图像。研究结果如下：(1)将化学需氧量摄像机直接连接到MAES装置的MCP检测部分。新的数据分析系统与摄像机相结合，使我们能够通过图像处理来灵敏地观察MeEM图像。(2)衬底(硅单晶的表面、石墨和MoS_2晶体的解理面、金刚石膜等)都是通过加热清洗的。用低能电子衍射(Leed)、电子能量损失谱(EELS)和亚稳态原子电子能谱(MAES)对清洗过程进行了观察。(3)Org…样品更多的烷类化合物(酞菁类、PTCDA类)通过真空升华沉积在上述衬底上。用MEEM和LEEM观察了薄膜随时间的变化和分子的扩散过程。(4)用PIES(Penning电离电子能谱)、ARUPS(角度分辨紫外光电子能谱)和HREELS(高分辨电子能量损失谱)在普通表面分析仪器上沉积了两种样品(有机化合物和In等金属)。在上述结果的基础上，阐明了反应速率、反应在分子中的位置以及电子态变化的动态过程。较少

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