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Scanning Tunnelling Microscopy Introduction The STM with its unmatched combination of high vertical and lateral resolution in a promising new tool that can be operated under ambient conditions, yielding three-dimensional detailed images, (H. Strecker and G. Persch, 1990, p441-445). The scanning tunnelling microscope (STM) is a solid-state microscope based on the principle of quantum mechanical tunnelling of electrons between a sharp tip and a conducting sample. Surfaces can be studied by allowing the individual atoms to be imaged in real space. By scanning the tip across a sample surface it is possible to image directly the three dimensional structure of a surface down to atomic scale resolutions. Prior to the invention of STM, the only way that surface structures could be deduced was by more indirect methods such as low energy electron diffraction (LEED) or medium-energy ion scattering (MEIS). Technique The tip used in STM is very sharp and ideally terminates into a single...

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