Light for the 2014 Nobel Prizes in Physics and in Chemistry
A Nobel Prize for enlightening the Earth. Another one to see the nanoworld. Light for both.
The Nobel Committee has awarded this year two practical inventions, the blue Light Emitting Diodes [LEDs] and the super-resolved fluorescence microscopy. Those are revolutionary and both use light to overcome technological barriers.
The 2014 Physics Nobel Prize goes to Isamu Akasaki and Hiroshi Amano from Japan, and to Shuji Nakamura from USA, “for the invention of efficient blue light emitting diodes which has enabled bright and energy-saving white light sources”. In the past producing bright visible light was routinely done by using semi-conductor diodes, to make electrons fall into holes having the right energy gap to release the energy corresponding to red, yellow or green photons. However, blue photons that require higher gaps could not be created, which banned the access to white lamps. To create blue LEDs, Nakamura exploited special crystals, indium gallium nitrides, providing the desired energy gaps. Besides, Asaki and Amano found out suitable surfaces on which these crystals could grow. In 1992, the first diode emitted blue light. The result of all these combined efforts is an invention that will benefit most people. Blue LEDs complete the rainbow of colored diodes to produce white energy-saving light sources. Present everywhere, these revolutionary light sources can supply four times more luminous efficiency than current fluorescent light. They have such a considerable economic and environmental impact that, as emphasized by the Nobel Committee, “the 21st century will be lit by LED lamps”.
The 2014 Chemistry Nobel Prize has been awarded to Stefan Hell from Germany and to Eric Betzig and William Moerner from USA “for the development of super-resolved fluorescence microscopy”. So far, due to Abbe resolution limit, an optical microscope could not discern features smaller than half the wavelength of the light used by this device. Betzig, Hell and Moerner surpassed this limitation to see the nanoworld. Hell developed the new concept of stimulated emission depletion [STED] microscopy, exploiting two laser pulses to monitor molecular fluorescence. Betzig and Moerner instead developed the single-molecule microscopy: a light pulse illuminates a sample tagged with fluorescent proteins, a small fraction of which lights up. An image is taken and the procedure is repeated by means of fast stimulations, producing a resulting picture that circumvents Abbe’s limit. These breakthroughs nowadays permit to visualize volumes extending over nanometer dimensions. Unlike the electron microscopy requiring vacuum around the sample, the fluorescence-based optical microscopy applies to living tissues and is able to scan life at unprecedented levels of spatial resolution.
The 2014 Nobel Prizes in Physics and Chemistry have been attributed to scientists working with light. They announce a brilliant International Year of Light.
