Analysis of Solid Surfaces by Means of Penning Ionization Electron Spectroscopy and High Resolution Electron Energy Loss Spectroscopy

尽管最近固体表面的研究取得了很大的进展，但在固体表面上发生的反应过程还没有得到很好的理解。这似乎是由于对最外层有选择性敏感的表面分析方法尚未得到很好的应用。在本研究中，我们尝试开发一种结合了Penning电离电子能谱（PIES）和HREELS（高分辨率电子能量损失能谱）的表面分析新方法。PIES选择性地提供固体最外层的电子状态信息，而HREELS使我们能够灵敏地检测最外层的原子和分子振动。为了达到上述目的，我们设计并构建了一台包括LEED（低能电子衍射）、AES（俄歇电子能谱）、UPS（紫外光电子能谱）以及PIES和HREELS的仪器。利用多仪器研究了洁净Ni（100）表面及其吸附的CO。利用LEED和AES分析了表面的结构和原子组成，利用PIES和UPS分析了表面的电子态，利用HREELS分析了表面的振动态。<He^*> PIES的测量结果如下：在干净的Ni表面，亚稳氦原子的2s电子转移到Ni表面形成<He^+>离子。因此，对应的光谱与INS（离子中和光谱）给出的光谱相似。另一方面，在吸附表面，由于Ni表面被CO原子屏蔽，Penning电离过程发生。在这种情况下，暴露在吸附表面外的单个轨道的电子分布的直接信息可以通过pie获得。除上述研究外，还利用PIES和UPS对各种有机薄膜的表面进行了表征。实验结果表明，pie可以灵敏地探测固体最外层分子取向和电子态的变化。特别是，最近注意到的LB （Langmuir-Blodgett）薄膜中的分子取向被发现是由pie直接知道的，即使是由一到几个单层组成的超薄薄膜。少

Although much progress has recently been made in the study of solid surfaces, the process of reactions taking place on the surfaces has not been well understood. This seems to be due to the fact that surface-analysis methods which are selectively sensitive to the outermost surface layer have not been well applied. In this study, we tried to develop a new method of surface analysis with the combination of PIES (Penning ionization electron spectroscopy) and HREELS (high resolution electron energy loss spectroscopy). PIES provides information on the electronic state of the outermost surface layer of solid selectively, whereas HREELS enables us to detect atomic and molecular vibrations at the outermost layer sensitively.To achieve the above purpose, we designed and constructed an instrument including the appratuses for LEED (low energy electron diffraction), AES (Auger electron spectroscopy), and UPS (ultraviolet photoelectron spectroscopy) together with those for PIES and HREELS. Using th … More is instrument, we studied surfaces of clean Ni(100) and CO adsorbed on it. The structure and atomic composition of the surfaces were investigated by LEED and AES, the electronic state by PIES and UPS, and the vibrational state was examined by HREELS. The measurements of <He^*> PIES gave the following results. On the clean Ni surface the 2s electon of a metastable helium atom transfers to the Ni surface to form a <He^+> ion. Therefore, the corresponding spectrum is similar to that given by INS (ion neutralization spectroscopy). On the adsorbed surface, on the other hand, Penning ionization process takes place because the Ni surface is shielded by CO atoms. In this case, direct information on the electron distribution of individual orbitals exposed outside the adsorbed surface can be obtained by PIES.In adition to the above study, the characterization of surfaces of various organic thin films was performed by PIES and UPS. It has been confirmed that PIES enables us to detect sensitively the changes in the molecular orientation and electronic state at the outermost surface layer of solid. In particular, the molecular orientation in LB (Langmuir-Blodgett) films noted recently has been found to be directly known by PIES even in the cases of ultra-thin films composed of one to several monolayers. Less