MRI: Acquisition of a Fully Cryogenic Scanning Tunneling Microscope

在主要研究仪器MRI项目的支持下，哥伦比亚大学化学系将获得一台全低温扫描隧道显微镜（STM）。该设备将加强若干领域的研究，包括a)反应中间体的局部探测；B)自组装单层膜的结构、电子性质和相互作用；C)分子电荷输运的研究；D) a维纳米结构的研究和操作；e)扫描隧道显微镜与光学激发/发射相结合。扫描隧道显微镜是一种表面分析技术，它允许人们绘制出导电表面的原子轮廓。将金属尖端磨成一个原子点，使其非常接近导电材料的表面。如果对尖端施加一个小电压，使尖端非常靠近表面，电流就会流过尖端和表面之间的间隙。由于隧穿电流的大小是间隙距离的函数，如果测量尖端穿过表面时的电流，就可以确定表面的原子信息。STM是研究金属和半导体表面的一个非常强大的工具。

With support from the Major Research Instrumentation MRI) Program, the Department of Chemistry at Columbia University will acquire a fully cryogenic scanning tunneling microscope (STM). This equipment will enhance research in a number of areas including a) local probing of reaction intermediates; b) structure, electronic properties and interactions of self-assembled monolayers; c) investigations of molecular charge transport; d) investigation and manipulation of a-dimensional nanostructures; and e) combining scanning tunneling microscopy and optical excitation/emission. Scanning tunneling microscopy is a surface analytical technique that allows one to map out the atomic contours of a conducting surface. A metallic tip, sharpened to a single atom point, is brought very close to the surface of a conducting material. If a small voltage is applied to the tip, and the tip is brought very close to the surface, a current flows across the gap between the tip and surface. Since the magnitude of this tunneling currect is a function of the gap distance, if one measures the current as the tip moves across the surface, atomic information of the surface can be determined. STM is an extremely powerful tool for studying metal and semiconductor surfaces.