Dynamic imaging of colloidal-crystal nanostructures at 200 frames per second.

The dynamic noninvasive imaging of colloidal nanostructures has been precluded by the diffraction-limited resolution of (confocal) light microscopy. Using Fast Stimulated Emission Depletion (STED) microscopy, we demonstrate the ability to resolve the formation of a colloidal crystal (monolayer) from particles of 200 nm size, where the voids in the crystal are as small as 30 nm. With a temporal resolution of 5 ms, we exemplify the technique by visualizing the annealing of potential point defects during the formation of the colloidal crystal.