Taming Tiny, Unruly Waves for Nano OpticsOctober 09, 2007Nanoscale devices present a unique challenge to any optical technology - there's just not enough room for light to travel in a straight line. On the nanoscale, energy may be produced by radiating photons of light between two surfaces very close together (sometimes as close as 10 nanometers), smaller than the wavelength of the light. Light behaves much differently on the nanoscale as its wavelength is interrupted, producing unstable waves called evanescent waves. The direction of these unpredictable waves can't be calculated, so researchers face the daunting task of designing nanotechnologies to work with the tiny, yet potentially useful waves of light. Researchers at Georgia Tech have discovered a way to predict the behavior of these unruly waves of light during nanoscale radiation heat transfer, opening the door to the design of a spectrum of new nanodevices (or NEMS) and nanotechnologies, including solar thermal energy technologies. Their findings were featured on the cover of the Oct. 8 issue of Applied Physics Letters.
"This discovery gives us the fundamental information to determine things like how far apart plates should be and what size they should be when designing a technology that uses nanoscale radiation heat transfer," said Zhuomin Zhang, a lead researcher on the project and a professor in the Woodruff School of Mechanical Engineering. "Understanding the behavior of light at this scale is the key to designing technologies to take advantage of the unique capabilities of this phenomenon." The Georgia Tech research team set out to study evanescent waves in nanoscale radiation energy transfer (between two very close surfaces at different temperatures by means of thermal radiation). Because the direction of evanescent waves is seemingly unknowable (an imaginary value) in physics terms, Zhang's group instead decided to follow the direction of the electromagnetic energy flow (also known as a Poynting vector) to predict behavior rather than the direction of the photons. "We're using classic electrodynamics to explain the behavior of the waves, not quantum mechanics," Zhang said. "We're predicting the energy propagation - and not the actual movement - of the photons." The challenge is that electrodynamics work differently on the nanoscale and the Georgia Tech team would need to pinpoint those differences. Planck's law, a more than 100-year-old theory about how electromagnetic waves radiate, does not apply on the nanoscale due to fact that the space between surfaces is smaller than a wavelength. The Georgia Tech team observed that instead of normal straight line radiation, the light was bending as protons tunneled through the vacuum in between the two surfaces just nanometers apart. The team also noticed that the evanescent waves were separating during this thermal process, allowing them to visualize and predict the energy path of the waves. Understanding the behavior of such waves is critical to the design of many devices that use nanotechnology, including near-field thermophotovoltaic systems, nanoscale imaging based on thermal radiation scanning tunneling microscopy and scanning photon-tunneling microscopy, said Zhang. Georgia Institute of Technology Science News and Science Current Events Tag Cloud This tag cloud is a visual representation of term frequencies of random science news topics with common terms grouped together and emphasized by their display size. Periodontitis Iron Back Pain HIV-1 Mangrove Drug Addiction Dementia Cosmic Radiation Search Engine Amblyopia Pluto Addiction Fusion Cavities Immune System Obstructive Sleep Apnea Vaccine Crohn's Disease Nanospheres Glutamate Dead Zone Cancer Detection In-vitro Fertilization Learning Parkinson Disease
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Related Nanoscale Current Events and Nanoscale News Articles Unexpectedly long-range effects in advanced magnetic devices A tiny grid pattern has led materials scientists at the National Institute of Standards and Technology (NIST) and the Institute of Solid State Physics in Russia to an unexpected finding-the surprisingly strong and long-range effects of certain electromagnetic nanostructures used in data storage. New statistical technique improves precision of nanotechnology data A new statistical analysis technique that identifies and removes systematic bias, noise and equipment-based artifacts from experimental data could lead to more precise and reliable measurement of nanomaterials and nanostructures likely to have future industrial applications. A new approach to engineering for extreme environments Composite materials such as fiberglass, which take on a mix of properties of their constituent compounds, have been around for decades. Now, an MIT materials scientist is taking composites to the nanoscale, where entirely new properties, not found in any of the original compounds, can emerge. Like burrs on your clothes, molecule-size capsules can deliver drugs by sticking to targeted cells It is now possible to engineer tiny containers the size of a virus to deliver drugs and other materials with almost 100 percent efficiency to targeted cells in the bloodstream. Stream of sand behaves like water University of Chicago researchers recently showed that dry granular materials such as sands, seeds and grains have properties similar to liquid, forming water-like droplets when poured from a given source. Research explores interactions between nanomaterials, biological systems The recent explosion in the development of nanomaterials with enhanced performance characteristics for use in commercial and medical applications has increased the likelihood of people coming into direct contact with these materials. Mechanics: Ordinary meets quantum At the quantum level, the atoms that make up matter and the photons that make up light behave in a number of seemingly bizarre ways. UGA researchers achieve breakthrough in effort to develop tiny biological fuel cells University of Georgia researchers have developed a successful way to grow molecular wire brushes that conduct electrical charges, a first step in developing biological fuel cells that could power pacemakers, cochlear implants and prosthetic limbs. The journal Chemical Science calls the technique "a significant breakthrough for nanotechnology." Natural deep earth pump fuels earthquakes and ore For the first time scientists have discovered the presence of a natural deep earth pump that is a crucial element in the formation of ore deposits and earthquakes. ORNL finding could help electronics industry enter new phase Electronic devices of the future could be smaller, faster, more powerful and consume less energy because of a discovery by researchers at the Department of Energy's Oak Ridge National Laboratory. More Nanoscale Current Events and Nanoscale News Articles |
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