Atomic-force microscopy works by scanning a surface with a tiny cantilever whose tip comes to a sharp nanoscale point. As it scans, the cantilever bounces up and down, and data from these movements is compiled to generate a picture of that surface. These microscopes can be used to "see" features much smaller than those visible under light microscopes, whose resolution is limited by the properties of light itself. Atomic-force microscopy literally has atom-scale resolution.
Until now it hasn't been possible to use it to look with atomic resolution at single molecules. Researchers overcame this problem by first using the microscope tip to pick up a single molecule of carbon monoxide, which they used to make an image of pentacene. They hope that looking this closely at single molecules will give them a better understanding of chemical reactions and catalysis at an unprecedented level of detail.