A team of researchers at Justus Liebig University Giessen has found a way to dramatically improve the images of topologically complex 3-D molecules created using atomic force microscopy (AFM). In their paper published in the journal Physical Review Letters, the group describes the simple adjustment they made to the procedure that greatly improved the resolution of AFM.
It has been nearly a decade since AFM was introduced, allowing researchers to create images of single molecules and better understand how molecules are assembled. But the technique suffers from a major deficiency—it only works on nearly flat molecules. Those molecules with more complex 3-D characteristics are visualized only partially clearly. The reason is that the tip of the sensor oscillates at a fixed distance from the molecule under study. This means only the parts of the molecule closest to the sensor are clearly visualized. Logic has suggested that the way to fix this problem is to move the tip of the probe up and down along a path that mimics the topology of the molecule. But such an approach has proven to be elusive. Tracking the hills and valleys in real time and moving the tip just the right amount has, until now, been untenable.