STM Analysis of Growth Process and Electronic Properties of microcluster.

为了分析具有给定原子数的微团簇的电子结构和原子结构，我们建立了质量选择微团簇制备系统和超高真空扫描隧道显微镜(UHV-STM)。团簇制备系统由自流离子枪和高分辨质谱仪组成。我们的STM是基于Deniuth的模型，并与家用I-NADE反馈电路一起计算。控制软件用Turbo C V.1编写。除了这些仪器的结构外，我们还对空气中的微团簇和细颗粒进行了STM分析，这些微团和细颗粒是通过三种不同的方法制备的：(1)热汽化，(2)激光汽化，(3)电化学反应。用扫描隧道显微镜(STM)研究了空气中金颗粒在石墨表面的生长过程。我们在原子分辨率上观察到直径约为2 nm的帽状微团簇，它们是形成金膜的核心。金的细小颗粒是在形核后的形核位置形成的。这些颗粒通过较小颗粒之间的结合聚集成较大的颗粒和/或金膜的岛。颗粒和岛的形态依赖于衬底的温度，而衬底的温度又与颗粒之间的聚结程度有关。在空气中用扫描隧道显微镜分析了激光蒸发制备的石墨表面的颗粒。激光蒸发法的成核程度是热蒸发法的10‘倍。这一事实与激光蒸发离子的较高能量有关，这是通过蒸发粒子辐射的荧光的时间和空间分辨光学测量来分析的。利用电化学扫描隧道显微镜对电沉积过程进行了研究。我们获得了颗粒在液-石墨界面生长和结合过程中的原位扫描隧道显微镜图像。

In order to analyze electronic and atomic structures of a microcluster with a given number of atoms, we have constructed a system for the preparation of mass-selected microclusters, and an scanning tunneling niicroscope for an ultra-high vacuum system(UHV-STM). The cluster-preparation system consists of zi liigii-current ion gun and a high-resolution mass spectrometer. Our STM is based on a model by Deniuth, and is computcr-cojitrolled with a home-i-nade feed back circuit. The control software is written using Turbo C++ V. 1. In addition to tiic construction of these instruments, we have made STM analyses of the microclusters and fine particles in air, which are prepared by three different methods : (1)thermal vaporization, (2)laser vaporization, and(3)electrochemical reaction. The growth process of gold particles on the graphite surface has been analyzed by STM in air. We have observed cap-shaped microclusters of about 2 nm in diameter in an atomic resolution which serve as nuclei for the gold-film formation. The gold fine-particles are formed at the nucleation sites after the formation of the nuclei. The particles aggregate into larger particles and/or islands of gold films through coalescence between smaller particles. The morphology of particles and islands is dependent on the temperature of the substrate, which is related with the degree of coalescence between particles. The particles on the graphite surface prepared by laser vaporization are also analyzed by STM in air. The degree of formation of nuclei by laser vaporization is 10' times as high as that by thermal vaporization. This fact is associated with higher energy of laservaporized ions, which is analyzed by the time- and space-resolved optical-measurements of fluorescence radiated from vaporized particles. The electrodeposition process is studied by electrochemical STM. We have obtained in-situ STM images during growth and coalescence of particles at liquid-graphite interface.