Development of In-situ Non-lenear Spectroscopic Probe microscope and its Application to the Surface Phenomena

发生在固-液界面上的化学和物理过程从基本原理和技术角度都得到了重视。近年来，扫描探针显微镜和非线性表面光谱仪开始揭示界面现象的新方面。本文利用扫描隧道显微镜(STM)和二次谐波、和频(SFG)等非线性激光光谱在分子水平上研究了电极表面发生的化学反应。在电化学STM研究中，考察了几种制备方法，以获得可用于STM测量和循环伏安测量的最佳电极尖端。将制备的电极浸泡在Fe(III)原卟啉(Fe-PP)水溶液中，用蒸馏水冲洗后转移到电化学池中。扫描隧道显微镜测量在缓冲液(PH 10)中进行。IT Wa…S进一步发现，当吸附量较大时，吸附在石墨电极上的Fe-PP呈现多层结构，且每一层都是具有规则晶格常数的有序结构。与此相反，当吸附分子量较少时，Fe-PP形成线性链。这些观察结果阐明了发生在电极表面的化学过程，即Fe-PP的物理结构取决于覆盖度。为了获得吸附产物的化学结构，用共振二次谐波光谱分析了亚甲基蓝在硫化涂层电极表面的氧化还原行为。因此，可以讨论吸附量与晶面取向和电子结构的关系。在光纤陀螺方面，研制了基于差频脉冲激光器的光纤陀螺测量系统，分析了影响测量的主要因素。虽然光谱分辨率不够高，但十八醇在Au(111)电极上的振动光谱的分辨率可达20 cm~(-1)~(-1)。如上所述，结合电化学扫描隧道显微镜和表面灵敏非线性激光光谱仪，可以在分子水平上分析发生在固-液界面上的化学过程。较少

Chemical and physical processes occured at solid-liquid interfaces have been paid attentions from the fundamental and technological points of view. In recent years, scanning probe microscopes and non-linear surface spectroscopies have began to reveal new aspects for the interfacial phenomena. In the present study, chemical reactions occured at electrode surfaces were studied at a molecular level by scanning tunnel microscope (STM) and non-linear laser spectroscopies such as second harmonic generation and sum frequency generation (SFG).In the electrochemical STM study, several preparation methods were examined for obtaining an optimum tip which can be used for the measurements of STM and cyclic voltammetry. The tips prepared were also evaluated by SEM.An electrode was immersed in an aqueous solution of Fe (III) protoporphyrin (Fe-PP), and then transferred to an electrochemical cell after rinsing with distillled water. STM meaaurements were carried out in a buffer solution (pH 10). It wa … More s found that Fe-PP absorbed on a graphite electrode showed multi-layred structure when the amount of adsorption is rich, and that the well-ordered structure having a regular lattice constant was observed for each adlayr. In contrast to this observation, Fe-PP was found to form a linear chain when the amount of adsorbed molecules is poor. These observations clarified the chemical process occured at the electrode surface, that is, the physical structures of Fe-PP depend on the coverage.To obtain chemical structure of adsorbate, resonant second harmonic spectroscopy was applied to the analysis of redox behaviors of methylene blue at the sulfer coated electrode surface. As a result, dependence of amount of adsorbate on the orientation and electronic structure could be discussed. As for SFG,measurement system was developped based on a pulsed Nd : YAG laser with a differential frequency generator, and fundamental factors which affect the measurements were examined. Although spectral resolution was not enough high, vibrational spectra of octadecanetiol on Au (111) electrode could be measured with a resolution of ca 20 cm^<-1>.As mentioned above, chemical processes occured at solid-liquid interfaces could be analyzed at a molecular level by combining the electrochemical STM with surface sensitive non-linear laser spectroscopies. Less