Imaging in real time with the tunneling microscope

We report the achievement of real-time video rate images of the atomic surface of graphite using the scanning tunneling microscope (STM). In this high-speed mode of operation the topographic information is extracted directly from variations in the tunneling current. We find that this high-speed technique offers the following advantages: the microscope becomes insensitive to most low frequency vibrations; piezoelectric scanner hysteresis appears to be reduced; and the effect of 1/f noise, which is conjectured to arise from diffusion of molecular species, is reduced by shifting the data to higher frequencies. The real-time technique offers the opportunity to observe dynamic atomic processes which occur on time scales previously incaccessible to the STM.