Using an atomic-force microscope, scientists at IBM Research in Zurich have for the first time made an atomic-scale resolution image of a single molecule, the hydrocarbon pentacene.
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.
Still, until now, it hasn’t been possible to use it to look with atomic resolution at single molecules. On such a scale, the electrical properties of the molecule under investigation normally interfere with the activity of the scanning tip. Researchers at IBM Research in Zurich overcame this problem by first using the microscope tip to pick up a single molecule of carbon monoxide. This drastically improved the resolution of the microscope, which the IBM scientists used to make an image of pentacene. They arrived at carbon monoxide as a contrast-enhancing addition after trying many chemicals.
The researchers 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.
The imaging work is described today in the journal Science.