Advancing Basic Science for Humanity
2014 Nanoscience Citation
|The Norwegian Academy of Science and Letters awards the
2014 Kavli Prize in Nanoscience to:
Thomas W. Ebbesen
University of Strasbourg, France
Stefan W. Hell
Max Planck Institute for Biophysical Chemistry, Germany
Sir John B. Pendry
Imperial College London, UK
|“for their 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 2014 KAVLI PRIZE IN NANOSCIENCE is awarded to Thomas Ebbesen, Stefan Hell, and Sir John Pendry “for their 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.”
‘Seeing’ has often been the precursor to our cultural and scientific understanding of the world. Scientists have realized this from the time of Hooke and van Leeuwenhoek in the 17th century when their innovations in optics opened up a new world at the micron scale. ‘Seeing at the nanoscale’ was long considered to be limited in visible resolution by the finite wavelength of ‘light’, so that only objects larger than ~ 200 nanometres could be imaged. This is about 100 times smaller than the diameter of a human hair. Other technologies have been developed to allow us to overcome these resolution limitations: for example, beams of electrons and scanning probe instruments. However, for ease of use and compatibility with biological specimens, optical microscopy has unparalleled advantages. Each of this year’s prize winners, through their different insights and routes, has independently advanced our ability to ‘see’ nanostructures using ‘ordinary’ light. This ability to see and image nanoscale objects is a critical prerequisite to further advances in the broader field of nanoscience. Thus, this year’s prize winners have not only advanced our understanding of nano-optics, but in addition, the application of these new insights into the imaging process in turn promises to have an enduring benefit to a wide range of fields ranging from physics and chemistry to the biological and biomedical sciences.
Thomas W. Ebbesen is recognized with the Kavli Prize in Nanoscience
“for the discovery of the extraordinary transmission of light through sub-wavelength apertures.”
‘Common wisdom’ tells us that objects cannot pass through openings which are much smaller than themselves. In fact, since the 1940s, the definitive reference for the behaviour of light transmitted through small holes in a metal sheet was Bethe’s work, which predicted that the light intensity would fall off dramatically as the radius of the hole diminished substantially below the wavelength of light. This limitation poses a real challenge to optics and imaging at very small dimensions. Ebbesen has shown that, on the contrary, there can be an extraordinary transmission of light through nano-fabricated holes in thin metal films. The sizes of those holes are far smaller than the wavelength of the light itself.
His experiments in 1998 yielded results that thus challenged all prior accepted theories of light propagation through small holes. The underlying reasons have to do with efficient re-radiation made possible through plasmons – a cooperative oscillation of electrons, particularly intense in nanoscale structures. Ebbesen’s understanding of the basic mechanism, and his implementation of different structures to enhance the focus, direction and general control of the plasmonic enhancement have led to new means of increasing the efficiency, spatial focus of photonic devices and sensitivity of optical sensors.
Stefan W. Hell is recognized with the Kavli Prize in Nanoscience
“for ground-breaking developments that have led to fluorescence microscopy with nanometre scale resolution, opening up nanoscale imaging to biological applications.”
Ernst Abbe demonstrated in 1873 that optical microscopy should not be able to discern features that are closer than half the wave-length of light. The Abbe limit became a cornerstone of optics that was not questioned for the next 120 years.
Hell met this challenge and overcame the diffraction limit by more than an order of magnitude. He accomplished this through understanding both the imaging mechanisms and the nature of what is being imaged. A key issue in the clarity of an image has always been distinguishing signal from a broad background of noise. By deeply understanding the composition of what is being imaged, be it biological or non-biological in nature, Hell showed how to control the background noise by strategically ‘shutting off’ molecular transitions at the appropriate time. He calls this ‘shutting off’ Stimulated Emission Depletion (STED): a technique that has now become accessible through instruments which he has helped to make commercially-available. Not only has STED enabled imaging at dimensions far smaller than optical wavelengths for a broad class of materials, it has in particular made this a viable option for the life sciences. Remarkably, Hell’s techniques have made possible direct observation of dynamical processes in living cells at nanoscale resolution.
Sir John B. Pendry is recognized with the Kavli Prize in Nanoscience
“for developing the theory underlying new optical nanoscale materials with unprecedented properties, such as the negative index of refraction, allowing for the formation of ‘perfect lenses’.”
For many of us, our association with ‘optics’ is with the corrective lenses we wear, which often have imperfections: the images that are not quite in focus or have ‘aberrations’ or rainbow-like haloes associated with the images. The issues are associated with the ways in which light ‘bends’ when going from air through lens material and into air again, and this is related to the index of refraction of those materials. Pendry has created a model for constructing a perfect lens, based on materials not normally found in nature. Such special materials have a negative index of refraction, as previously discussed by Veselago. It was Pendry’s insight to reinvestigate these ideas in the context of real materials such as silver, gold and copper, and to formulate the guidelines for the eventual realization of perfect lenses. With a growing body of experimental validation of his work, he has further stimulated a plethora of activities extending these concepts all the way across the visible spectrum and beyond.
Pendry has helped to formulate rules on how to incorporate different kinds of materials (metals and dielectrics) with nanoscale structures to form larger scale ‘metamaterials’ with exciting new optical properties that nature has not before provided us with. Thus, he encourages us to challenge our previously held ideas about the kinds of optical materials that we can engineer, promising dramatically improved levels of efficiency in light emission, storage and sensing.