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

固液界面发生的化学和物理过程从基础和技术的角度得到了关注。近年来，扫描探针显微镜和非线性表面光谱开始揭示界面现象的新方面。本研究采用扫描隧道显微镜（STM）和二次谐波产生、和频产生（SFG）等非线性激光光谱技术，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，研究了几种制备方法，以获得可用于STM和循环伏安法测量的最佳尖端。制备的针尖也通过扫描电镜进行了评价。将电极浸入Fe （III）原卟啉（Fe- pp）水溶液中，用蒸馏水冲洗后转移到电化学电池中。STM测量在缓冲溶液（pH 10）中进行。结果表明，Fe-PP吸附在石墨电极上，吸附量大时呈现多层结构，且每层结构均具有规则的晶格常数。与此相反，当吸附分子量较少时，发现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。为了获得吸附物的化学结构，应用谐振二次谐波光谱分析了亚甲基蓝在硫包覆电极表面的氧化还原行为。因此，可以讨论吸附质用量对取向和电子结构的影响。基于差频发生器的脉冲Nd: YAG激光器，研制了SFG测量系统，并对影响测量的基本因素进行了研究。虽然光谱分辨率不够高，但十八烷醇在Au（111）电极上的振动光谱分辨率约为20 cm^<-1>。如上所述，将电化学STM与表面敏感非线性激光光谱相结合，可以在分子水平上分析发生在固液界面的化学过程。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