The AES system provides detailed surface chemistry at the sub-10 nm scale. It operates by spectroscopy of Auger electrons (a multi-electron emission process) that are generated by an ultra-fine scanning electron probe. Chemical information from regions as small as 10 nm may be obtained, with chemical sensitivity of a few parts per thousand. The Auger signal is obtained from regions within about 1 nm of the surface, and an integrated ion sputtering enables the surface to be continuously removed, so that chemical depth profiles can be obtained. The system is maintained under ultra-high vacuum (~10^-10 Torr) conditions.