Scientists have found a new way to image tiny structures and molecules smaller than the 200 nm diffraction-limited resolution of optical microscopes.

The technique combined fluorescence lifetime imaging microscopy (FLIM) with atomic force microscopy (AFM) to generate sharp images of fluorescing nanobeads just 40 nm in diameter, as well as a cluster of DNA molecules.

It involves scanning a gold-tipped silicon wand over a fluorescing sample. The gold tip generates a strong electric field when illuminated with a laser. The interaction between the sample and this field provides the improved image contrast.

The hybrid imaging technique is non-destructive and thus ideal for probing the structure of biological molecules.