Surface Oxidation Kinetics: A Scanning Tunneling Microscopy Experiment

The study of surfaces and materials is underrepresented in the undergraduate chemistry curriculum. This is unfortunate because chemistry plays such a central role in the development of new materials. We have developed an undergraduate physical chemistry laboratory experiment in which students use the scanning tunneling microscope to study the oxidation of graphite by nitric oxide. The lab is designed to simulate a research experience. Each student is responsible for one part of the experiment and the whole class uses everyone's data for their analysis. A scanning tunneling microscope is used to measure the diameter of monolayer pits etched into the graphite by the nitric oxide. The results are both instructive and aesthetic. The data are used to determine the activation energy for the etching process. Several concepts that are explored from these results: crystallography, surface diffusion, bonding, defects, and reaction kinetics. We believe that the open-ended nature of both this experiment and the data analysis will result in better educated and more productive scientists.