Sharper than light permits
Generations of physicists believed in the Abbe limit until Stefan Hell tore up the text book with his unconventional ideas. The LASER World of PHOTONICS congratulates its Keynote Speaker at the “World of Photonics Congress 2013” on his Nobel Prize for Chemistry 2014!
Professor Dr. Stefan W. Hell wasn't short of awards. Following the German Future Prize 2006, the Leibniz Prize 2008, the Otto-Hahn Prize 2009 and the Meyenburg Prize 2011 he received the Kavli Prize for Nano sciences worth one million dollars from the hand of King Harald of Norway in September 2014.
He might just as well have stayed in the north because just a few weeks later on 8 October 2014 his phone rang, on the other end of the line was the Secretary of the Nobel Prize Committee, saying: Stefan Hell, Director of Biophysical Chemistry at the Max Planck Institute in Göttingen, together with Eric Betzig and William Moerner had won this year's Nobel Prize for Chemistry. The Royal Swedish Academy of Sciences is honoring the physicist's pioneering work in the field of super-resolved fluorescence microscopy.
The north seems to be a happy hunting ground for Stefan Hell because after studying for his physics degree at the University of Heidelberg and his work at the European Molecular Biology Laboratory (EMBL), from 1993 onward he developed the principle of STED microscopy (Stimulated Emission Depletion) at the University of Turku in Finland. After that the Max-Planck Society brought him back to Germany where he has been director of the Max Planck Institute for Biophysical Chemistry, in Göttingen since 2002.
Hell versus Abbe – Light microscopy revolutionized
With the invention of the STED (Stimulated Emission Depletion) microscopy experimentally realized by Hell in 1999, he has revolutionized light microscopy. Hell was the first to radically overcome the resolution limit of light microscopes - a breakthrough that has enabled new ground-breaking discoveries in biological and medical research. Hell used STED microscopy to demonstrate for the first time that the 200 nanometer limit of resolution of an optical microscope as determined by the wave nature of light can be overcome using STED microscopy. This had been deemed impossible since the work done by Ernst Abbe (1873). Fluorescence microscopy used in medicine also capitulated before this limit. This special type of optical microscopy entails the cell's molecules being labeled with fluorescing dyes and caused to emit light by specific laser light. If the molecules are within less than 200 nanometers of one another, they blur into a faded spot. Because of these diffraction effects it had previously been impossible to observe smaller structures in living cells.
Stefan Hell and his team use a trick to outsmart the diffraction of light. To this end, in a STED microscope they had a laser beam, which excites the fluorescent molecules, followed by a second beam, which immediately “de-excites” the molecules, keeping them dark. But to avoid all the molecules being switched off, the second beam has a hole in the middle. That means that only molecules on the periphery of the excited spot of light become dark whereas molecules at the center continue to emit light.
In addition to snapshots, the technique even makes it possible to track life processes within the living cells “live” with nanometer resolution. That meant that it was possible for the first time to “film” the movements of messenger substance vesicles in a nerve cell in real time – at 33 frames per second and a resolution of around 70 nanometers.
Stefan Hell described his idea - to radically overcome the resolution limit of conventional optical microscopes - to the Nobel Committee as follows: "Back then I intuitively felt that something has not been thought through thoroughly," Hell recalls. “That was 19th century physics. I thought, there has to be a way if one doesn't merely observe the objects but plays with them. You have to try to switch the molecules on and off to see more detail.”
So he did.
We congratulate Prof. Dr. Stefan Hell on the Nobel Prize!