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July 01, 2014
Stefan Hell and Thomas Ebbesen Share 2014 Kavli Prize in Nanoscience
ChemPhysChem Board Members Stefan Hell (Max Planck Institute for Biophysical Chemistry, Germany) and Thomas Ebbesen (University of Strasbourg, France) have been awarded this year's Kavli Prize in Nanoscience –one of the world's most prestigious recognitions in the field. They share the prize with Sir John B. Pendry (Imperial College London, UK) "for transformative contributions to the field of nano-optics that have broken long-held beliefs about the limitations of the resolution limits of optical microscopy and imaging". The Kavli Prize is awarded every other year by The Norwegian Academy of Science and Letters. The winners will receive their recognition from the King of Norway at a ceremony this September.
"I feel very honored by the Kavli Prize and it has of course additional meaning to me because it is given in my native country", says Thomas Ebbesen, who was born in Oslo. "I am also very grateful to all the students and colleagues with whom I have had very enriching interactions over the years", he adds. Ebbesen's results in 1998 challenged all previously accepted theories of light propagation through small holes. He discovered that there can be an extraordinary transmission of light through apertures whose sizes are far smaller than the wavelength of light. One would expect that objects cannot pass through openings that are much smaller than themselves, but Ebbesen explained his unforeseen observations by an efficient re-radiation, which is made possible through plasmons (a collective oscillation of electrons). The implementation of different structures allowed him to improve the focus, direction, and general control of this plasmonic enhancement. "Controlling the electromagnetic field/environment on the sub-wavelength scale has raised fundamental issues and opened a wealth of possibilities for imaging, sensing, and telecommunication that this year's Kavli Prize in Nanosciences recognizes", Ebbesen says.
Stefan Hell's work has revolutionized nanoscience in a similar way. With the invention and subsequent development of stimulated emission depletion (STED) microscopy and related techniques, he was able to work around the diffraction barrier proposed by the German physicist Ernst Abbe in 1873. At that time, Abbe demonstrated that the resolution of an imaging instrument is limited by the wavelength of the light used and the aperture of its optics. This barrier was considered unbreakable and had not been questioned for more than a century. "In the late 1980s and early 1990s, I became fascinated by the question whether the resolution of a lens-based (far-field) optical microscope was really fundamentally limited by the wavelength of light, as had been stated in textbooks and reiterated in introductory paragraphs", Hell says. "At some point I became convinced that some physical phenomena must exist that –if properly harnessed– would allow one to overcome the diffraction barrier, meaning separating features that are smaller and closer together than half the wavelength of light".
One idea he had was to check out what the molecules of the object that he was looking at could offer, so he screened for state transitions that would enable separating features, no matter what molecules and no matter what transition: "I felt that this must be easiest to accomplish with fluorophores, because of the wide range of state transitions that these molecules offer. Besides, they were already widely used in fluorescence microscopy. After a while, I realized that silencing a fluorophore by stimulated emission or keeping it in a metastable dark state would be very powerful for separating fluorophores at sub-diffraction length scales. Today, both phenomena are in wide use in so-called superresolution fluorescence microscopy". Hell agrees that this year's prize is a well-deserved distinction for many researchers working in the field of nano-optics: "It is a very important recognition, not only for me, but also for the people who worked with me and, in fact, the whole area of developing far-field optical microscopy with diffraction-unlimited resolution", he says.
The Kavli prize was first awarded in 2008 and honors outstanding achievements in the fields of nanoscience, astrophysics, and neuroscience.
Photos: Stefan Hell (left) and Thomas Ebbesen (right, credit: Catherine Schröder/Unistra) are two of the winners of this year's Kavli Prize in Nanoscience.
Related article: Nobel Prize in Chemistry 2014: Breaking the Barrier.