Pushing the limits of SPM

In the two decades since the invention of the scanning tunneling microscope (STM)1, the family of local probing techniques known as scanning probe microscopy (SPM) has come to full maturity. Nowadays, the quality with which nanoscale images can be obtained and local spectroscopic information acquired using these instruments is spectacular. In addition, the ease of use of these machines has improved so much that they have found their way into the laboratories, not just of physicists, but also chemists, biologists, and engineers.