STM Design Considerations

Although the concept is simple, the actual realization of an STM apparatus is a 

the teehnical difficulties have largely been overcome, and STM instruments that routinely provide atomic resolution on surfaees have been built 41,54-56). This capability has greatly facilitated the applications of the mieroseope in surfaee science, and recently the technique has been improved even further, allowing investigations of more complex samples such as model eatalysts eonsisting of nanoclusters on flat single-crystal surfaces. 

In most of the research summarized here, a homebuilt UHV-eompatible Aarhus STM instrument (Fig. lb) was used, which represents a sueeessful solution to the problem of designing a stable high-resolution microscope (JJ). It features state-of-the-art atomic resolution, and the compact, rigid design with a high meehanieal frequency also allows for high sampling frequencies (i.e., fast data aequisition that enables observation of dynamic processes on the surface) 57). 

Although the concept is simple, the actual realization of an STM apparatus is a major challenge. The mechanical design of an STM instrument has the inherent 

---

The Scanning Tunneling Microscope has demonstrated unique capabilities for the examination of electrode topography, the vibrational spectroscopic imaging of surface adsorbed species, and the high resolution electrochemical modification of conductive surfaces. Here we discuss recent progress in electrochemical STM. Included are a comparison of STM with other ex situ and in situ surface analytic techniques, a discussion of relevant STM design considerations, and a semi-quantitative examination of faradaic current contributions for STM at solution-covered surfaces. Applications of STM to the ex situ and in situ study of electrode surfaces are presented. 

---