Verleihungszeremonie in Stockholm

Stefan W. Hell, however, has come up with the crucial idea of bypassing the diffraction limit of light. This has earned him the Nobel Prize in Chemistry together with US American researchers Eric Betzig and William Moerner. With his STED microscope (Stimulated Emission Depletion), he developed a technology enabling researchers to investigate individual molecules in living cells at up to ten times the previously possible resolution. The process uses the characteristics of fluorescence dyes. The STED method employs two laser beams; the first laser beam stimulates fluorescent markers within the cells to glow, the second cancels out all fluorescence except for that in those molecules that are of interest to the researchers. The second laser beam returns all other molecules to their original state, switching their fluorescence off. This enabled Hell to minimise the focal spot, that is, to reduce the number of light points under the microscope so that the glare does not obscure everything else. This renders finest structures visible. The sophisticated method enables the observation of processes in living cells on a scale of 20 to 50 nanometres. "At the start", Stefan Hell looks back, "nobody wanted to believe in it. But now it is clear: the vision of optical nanoscopy has become a reality."

The STED microscopes developed by Hell are used worldwide for researching biological processes and contribute to the rapid progress in medical basic research. In his capacity as head of the Division Optical Nanoscopy at the German Cancer Research Center (DKFZ) in Heidelberg, Hell and his team work on further developing STED microscopy in medical basic research. The huge advantage of the method is that also living cells can be investigated on a nanometre scale. "It is a great feeling to see STED microscopy giving such a huge boost to medical basic research", says Hell.