Spectroelectrochemical Study of High-index Platinum Surfaces with terrace, step and kink sites.

本研究的主要目的是阐明具有不同吸附位点的单晶表面的性质；即阶梯网站，扭结网站和露台网站。这项工作的突出特点是所有的实验都是在原位条件下进行的，即在电化学电池中，这对于从原子尺度的角度解释催化和电化学是非常重要的。首先，用红外反射吸收光谱法研究了CO吸附在Pt（111）、（110）、（100）、（1111）和（711）等单晶表面上的复层结构。在这些电极表面至少存在四种不同的CO吸附带，即阶梯状和阶梯状原子上的顶部CO， 2045、2060、1880和1910 cm^<-1>附近的对称和非对称桥状CO。通过改变外加电位、表面覆盖率和检测时间尺度，观察了这些红外波段的波段强度及其频率的特征行为。本工作的第二个主题是阐明表面增强拉曼散射效应的详细机制。为了增强吸附物质的拉曼信号，原子尺度的粗糙度是决定因素。在这项研究中，已知的粗糙度是由几个原子组成的金属团簇。电容器的电子状态一定会影响SERS的增强。

The main purpose of this research is to clarify the nature of the single crystal surface which has different kinds of adsorption sites; i.e. step sites, kink sites and terrace sites. The prominent feature of this work is that all the experimentals were performed in situ condition, i.e. in electrochemical cells, and this is quite important for the elusidation of catalysis and electrochemistry in the atomic-scale point of view.At first, overlayer structures of CO adsorbed on several single crystal surfaces, Pt(111), (110), (100), (11 1 1) and (711), have been investigated by infrared reflection absorption spectroscopy. There exist at least four kinds of adsorption bands of CO on these electrode surfaces, i.e. on-top CO on stepped and terrace atoms, symmetric and asymmetric bridge CO at around 2045, 2060, 1880 and 1910 cm^<-1>, respectively. By changing the applied potental, surface coverages and detection time scale, the characteristic behavior of the band intensities as well as their frequencies of these IR bands were observed.Second theme of this work was the elucidation of detailed mechanism of surface enhanced Raman scattering effect. To enhance the Raman signals of adsorbed species, atomic scale roughness is the determining factor. In this research, the roughness has been known to be the metal clusters consisted of several atoms. The electronic states of the culster must affect the enhancement of SERS.