Standard STM is relatively slow. The time it takes to scan one image depends on the image size, but typically it is of the order of one minute. Dynamic processes are therefore hardly accessible. In order to monitor time dependent processes we have developed equipment for a high-speed STM. Image rates of up to 20 frames per second are achieved.
Fig.: Real-time STM of surface diffusion. The movie, displayed in real time, shows adsorbed O atoms on a Ru(0001) surface at room temperature. Individual O atoms are mobile under these conditions. Attractive interactions between neighboring atoms lead to island formation in which the atoms are completely immobilized.