Abstract
The invention of the scanning tunnelling microscope by Gerd Binnig and Heinrich Rohrer in the early 1980s with its ability to position a metal tip at molecular distances from a solid surface and obtain surface topographies with atomic resolution, has facilitated a wide range of novel surface physics experiments. In addition to the conventional mode of use of the scanning tunnelling microscope (STM) (see box overleaf), other new microscopic and spectroscopic techniques that use proximity electron emission from the tip are now being developed. Many of these involve using electrons that are generated by field emission from the tip; indeed recent advances in the preparation of atomically sharp field emission tips together with a better understanding of the STM itself mean that stable field emission sources are now routinely achievable.