Scanning tunneling microscopy (STM) has evolved rapidly in the past few years. Major developments have occurred in instrumentation, theory, and in a wide range of applications. In this paper, an overview of the application of STM and related techniques to polymers will be given, followed by a discussion of current research issues and prospects for future developments. The application of STM to polymers can be conveniently divided into the following subject areas: atomic scale imaging of uncoated polymer structures; topographic imaging and metrology of man-made polymer structures; and modification of polymer structures. Since many polymers are poor electrical conductors and hence unsuitable for use as a tunneling electrode, the related atomic force microscopy (AFM) technique which is capable of imaging both conductors and insulators has also been applied to polymers.The STM is well known for its high resolution capabilities in the x, y and z axes (Å in x andy and sub-Å in z). In addition to high resolution capabilities, the STM technique provides true three dimensional information in the constant current mode. In this mode, the STM tip is held at a fixed tunneling current (and a fixed bias voltage) and hence a fixed height above the sample surface while scanning across the sample surface.
Single-molecule high-resolution structure and electron conduction of Photosystem II from scanning tunneling microscopy and spectroscopy
