scanning probe microscopy scanning tunnelling microscopy scanning-tunnelling microscopy CHMO:0000132 STM scanning tunnelling electron microscopy scanning tunneling electron microscopy scanning-tunneling electron microscopy Microscopy which uses a sharp conducting probe (or 'tip') held very close (1 nm) to the surface of the specimen. A bias voltage is applied between the tip and specimen which causes a tunnelling current to flow. An image is obtained by mechanically moving the probe in a raster scan of the specimen, line by line, and recording the tunnelling current as a function of position. FIX:0000112