Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Breaking the law, at the nanoscale

Professor Gang Chen with the vacuum chamber used in this research.
Professor Gang Chen with the vacuum chamber used in this research.

Abstract:
Bringing objects close together can boost radiation heat transfer, according to new study that shows breakdown in Planck's law

Breaking the law, at the nanoscale

Cambridge, MA | Posted on July 30th, 2009

A well-established physical law describes the transfer of heat between two objects, but some physicists have long predicted that the law should break down when the objects are very close together. Scientists had never been able to confirm, or measure, this breakdown in practice. For the first time, however, MIT researchers have achieved this feat, and determined that the heat transfer can be 1,000 times greater than the law predicts.

The new findings could lead to significant new applications, including better design of the recording heads of the hard disks used for computer data storage, and new kinds of devices for harvesting energy from heat that would otherwise be wasted.

Planck's blackbody radiation law, formulated in 1900 by German physicist Max Planck, describes how energy is dissipated, in the form of different wavelengths of radiation, from an idealized non-reflective black object, called a blackbody. The law says that the relative thermal emission of radiation at different wavelengths follows a precise pattern that varies according to the temperature of the object. The emission from a blackbody is usually considered as the maximum that an object can radiate.

The law works reliably in most cases, but Planck himself had suggested that when objects are very close together, the predictions of his law would break down. But actually controlling objects to maintain the tiny separations required to demonstrate this phenomenon has proved incredibly difficult.

"Planck was very careful, saying his theory was only valid for large systems," explains Gang Chen, MIT's Carl Richard Soderberg Professor of Power Engineering and director of the Pappalardo Micro and Nano Engineering Laboratories. "So he kind of anticipated this [breakdown], but most people don't know this."

Part of the problem in measuring the way energy is radiated when objects are very close is the mechanical difficulty of maintaining two objects in very close proximity, without letting them actually touch. Chen and his team, graduate student Sheng Shen and Columbia University Professor Arvind Narayaswamy, solved this problem in two ways, as described in a paper to be published in the August issue of the journal Nano Letters (available now online). First, instead of using two flat surfaces and trying to maintain a tiny gap between them, they used a flat surface next to a small round glass bead, whose position is easier to control. "If we use two parallel surfaces, it is very hard to push to nanometer scale without some parts touching each other," Chen explains, but by using a bead there is just a single point of near-contact, which is much easier to maintain. Then, they used the technology of the bi-metallic cantilever from an atomic-force microscope to measure the temperature changes with great precision.

"We tried for many years doing it with parallel plates," Chen says. But with that method, they were unable to sustain separations of closer than about a micron (one millionth of a meter). By using the glass (silica) beads, they were able to get separations as small as 10 nanometers (10 billionths of a meter, or one-hundredth the distance achieved before), and are now working on getting even closer spacings.

Professor Sir John Pendry of Imperial College London, who has done extensive work in this field, calls the results "very exciting," noting that theorists have long predicted such a breakdown in the formula and the activation of a more powerful mechanism.

"Experimental confirmation has proved elusive because of the extreme difficulty in measuring temperature differences over very small distances," Pendry says. "Gang Chen's experiments provide a beautiful solution to this difficulty and confirm the dominant contribution of near field effects to heat transfer."

In today's magnetic data recording systems - such as the hard disks used in computers - the spacing between the recording head and the disk surface is typically in the 5 to 6 nanometer range, Chen says. The head tends to heat up, and researchers have been looking for ways to manage the heat or even exploit the heating to control the gap. "It's a very important issue for magnetic storage," he says. Such applications could be developed quite rapidly, he says, and some companies have already shown a strong interest in this work

The new findings could also help in the development of new photovoltaic energy conversion devices to harness photons emitted by a heat source, called thermophovoltaic, Chen says. "The high photon flux can potentially enable higher efficiency and energy density thermophovoltaic energy converters, and new energy conversion devices," he says.

The new findings could have "a broad impact," says Shen. People working with devices using small separations will now have a clear understanding that Planck's law "is not a fundamental limitation," as many people now think, he says. But further work is needed to explore even closer spacings, Chen says, because "we don't know exactly what the limit is yet" in terms of how much heat can be dissipated in closely spaced systems. "Current theory will not be valid once we push down to 1 nanometer spacing."

And in addition to practical applications, he says, such experiments "might provide a useful tool to understand some basic physics."

The work was funded by the U.S. Department of Energy and the Air Force Office of Scientific Research.

####

About MIT
The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the 21st century.

For more information, please click here

Contacts:
Jen Hirsch
MIT News Office
Phone: 617-253-2700

Copyright © MIT

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Scientists reveal breakthrough in optical fiber communications December 21st, 2014

Atom-thick CCD could capture images: Rice University scientists develop two-dimensional, light-sensitive material December 20th, 2014

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

Instant-start computers possible with new breakthrough December 19th, 2014

Govt.-Legislation/Regulation/Funding/Policy

Atom-thick CCD could capture images: Rice University scientists develop two-dimensional, light-sensitive material December 20th, 2014

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

Zenosense, Inc. - Hospital Collaboration - 400 Person Lung Cancer Detection Trial December 17th, 2014

SUNY Poly NanoCollege Faculty Member Selected as American Physical Society Fellow: SUNY Poly Associate Professor of Nanoscience Dr. Vincent LaBella Recognized for Significant Technological Innovations that Enable Interactive Learning December 17th, 2014

Possible Futures

A novel method for identifying the body’s ‘noisiest’ networks November 19th, 2014

Researchers discern the shapes of high-order Brownian motions November 17th, 2014

VDMA Electronics Production Equipment: Growth track for 2014 and 2015 confirmed: Business climate survey shows robust industry sector November 14th, 2014

Open Materials Development Will Be Key for HP's Success in 3D Printing: HP can make a big splash in 3D printing, but it needs to shore up technology claims and avoid the temptation of the razor/razor blade business model in order to flourish November 11th, 2014

Memory Technology

Instant-start computers possible with new breakthrough December 19th, 2014

Switching to spintronics: Berkeley Lab reports on electric field switching of ferromagnetism at room temp December 17th, 2014

Stanford team combines logic, memory to build a 'high-rise' chip: Today circuit cards are laid out like single-story towns; Futuristic architecture builds layers of logic and memory into skyscraper chips that would be smaller, faster, cheaper -- and taller December 15th, 2014

Graphene layer reads optical information from nanodiamonds electronically: Possible read head for quantum computers December 1st, 2014

Announcements

Scientists reveal breakthrough in optical fiber communications December 21st, 2014

Atom-thick CCD could capture images: Rice University scientists develop two-dimensional, light-sensitive material December 20th, 2014

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

Instant-start computers possible with new breakthrough December 19th, 2014

Military

Atom-thick CCD could capture images: Rice University scientists develop two-dimensional, light-sensitive material December 20th, 2014

UCLA engineers first to detect and measure individual DNA molecules using smartphone microscope December 15th, 2014

Nanoshaping method points to future manufacturing technology December 11th, 2014

Stacking two-dimensional materials may lower cost of semiconductor devices December 11th, 2014

Energy

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

How does enzymatic pretreatment affect the nanostructure and reaction space of lignocellulosic biomass? December 18th, 2014

Iranian Scientists Use Nanotechnology to Increase Power, Energy of Supercapacitors December 18th, 2014

Lifeboat Foundation gives 2014 Guardian Award to Elon Musk December 16th, 2014

Solar/Photovoltaic

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

Lifeboat Foundation gives 2014 Guardian Award to Elon Musk December 16th, 2014

Stacking two-dimensional materials may lower cost of semiconductor devices December 11th, 2014

New Technique Could Harvest More of the Sun's Energy December 9th, 2014

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More










ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE