Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists use molecular layers to study nanoscale heat transfer

29.10.2012
Scientific research has provided us with a fundamental understanding of how light (via photons) and electricity (via electrons) move within and between materials at the micrometer or nanometer levels, making possible a wide variety of miniature devices such as transistors, optical sensors and microelectromechanical systems (MEMS).

However, man's knowledge of micro- and nanoscale heat flow is rudimentary at best. Now, a research team at the University of Illinois at Urbana-Champaign (UIUC) has developed a novel system for examining and measuring nanoscale thermal conductance at the interface between two materials.

With further refinement, the scientists believe their advance may one day provide data for applications such as harvesting electricity from waste heat, better cooling of microelectronic devices and "heat-seeking" targeting of disease cells by hyperthermal (above normal body temperature) therapeutics.

The team's findings will be presented by Mark Losego, formerly a post-doctoral fellow at UIUC and now a research assistant professor in chemical and biomolecular engineering at North Carolina State University, during the AVS 59th International Symposium and Exhibition, held Oct. 28-Nov. 2, 2012, in Tampa, Fla.

At the nanoscale, thermal properties are the result of vibrations between neighboring atoms. Bonds between atoms carry these vibrations similar to an oscillating spring. The UIUC team developed a technique for studying the effects of these bonds on heat transport across an interface between two different materials. "We wanted a system where we could observe, analyze and quantify thermal flow across an interface with atomic-level precision," Losego says.

The system starts with a substrate base of quartz crystal, upon which the researchers place molecular chains that are 12 carbon atoms long. At the base of each chain is a chemical "cap" that covalently bonds to quartz. The attraction of these caps to the substrate spontaneously aligns all of the carbon chains into an ordered array of molecules known as a self-assembled monolayer (SAM). At the opposite end of each carbon chain is a different kind of cap, either a thiol (sulfur and hydrogen) group that bonds strongly to metals or a methyl group (carbon and hydrogen) that bonds weakly.

"We then make use of a viscoelastic silicone stamp to 'transfer print' gold layers onto the SAM surface," Losego explains. "This process is similar to transferring a decal onto a T-shirt where the gold film is the 'decal' attached to the silicone stamp 'backing'. When we slowly peel away the silicone, we leave the gold layer on top of the SAM."

It is at the interface between the gold film and the SAM, Losego says, where nanoscale heat flow is characterized. "Changing the chemical groups that are in contact with the gold layer allows us to see how different bonds affect heat transfer," he adds.

Combined with an ultrafast laser technique capable of monitoring temperature decay (or heat loss) with picosecond (trillionth of a second) resolution, the UIUC researchers are able to use their experimental system to evaluate heat flow at the atomic scale. "We heat the gold layer attached to the monolayer and can monitor temperature decay with time," Losego explains. "Concurrently, we observe oscillations in the gold film that indicate the strength of the bonds at the gold-SAM junction. Using these measurements we are able to independently verify that strong bonds [fast-decaying oscillations] have rapid heat transfer while weak bonds [slowly decaying oscillations] have slower heat transfer."

The researchers plan to refine their nanoscale thermal measurement system and develop theoretical calculations to better interpret the data it produces.


MORE INFORMATION ABOUT THE AVS 59th INTERNATIONAL SYMPOSIUM & EXHIBITION
The Tampa Convention Center is located along the Riverwalk in the heart of downtown Tampa at 333 S. Franklin St., Tampa, Florida, 33602.

USEFUL LINKS:

Main meeting website: http://www2.avs.org/symposium/AVS59/pages/greetings.html

Technical Program: http://www.avssymposium.org/

Housing and Travel Information: http://www2.avs.org/symposium/AVS59/pages/housing_travel.html

PRESS REGISTRATION

The AVS Pressroom will be located in the Tampa Convention Center. Your complimentary media badge will allow you to utilize the pressroom to write, interview, collect new product releases, review material, or just relax. The media badge will also admit you, free of charge, into the exhibit area, lectures, and technical sessions, as well as the Welcome Mixer on Monday evening and the Awards Ceremony and Reception on Wednesday night. Pressroom hours are Monday-Thursday, 8-5 p.m.

To register, please contact:

Della Miller, AVS
E-mail: della@avs.org
This news release was prepared for AVS by the American Institute of Physics (AIP).

ABOUT AVS

Founded in 1953, AVS is a not-for-profit professional society that promotes communication between academia, government laboratories, and industry for the purpose of sharing research and development findings over a broad range of technologically relevant topics. Its symposia and journals provide an important forum for the dissemination of information in many areas of science and technology, enabling a critical gateway for the rapid insertion of scientific breakthroughs into manufacturing realities.

Catherine Meyers | EurekAlert!
Further information:
http://www.aip.org

More articles from Physics and Astronomy:

nachricht The moon is front and center during a total solar eclipse
24.07.2017 | NASA/Goddard Space Flight Center

nachricht Superluminous supernova marks the death of a star at cosmic high noon
24.07.2017 | Royal Astronomical Society

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

Ultrathin device harvests electricity from human motion

24.07.2017 | Power and Electrical Engineering

Scientists announce the quest for high-index materials

24.07.2017 | Materials Sciences

ADIR Project: Lasers Recover Valuable Materials

24.07.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>