Navigation Links
Graphene yields secrets to its extraordinary properties
Date:5/14/2009

Applying innovative measurement techniques, researchers from the Georgia Institute of Technology and the National Institute of Standards and Technology (NIST) have directly measured the unusual energy spectrum of graphene, a technologically promising, two-dimensional form of carbon that has tantalized and puzzled scientists since its discovery in 2004.

Published in this week's issue of Science,* their work adds new detail to help explain the unusual physical phenomena and properties associated with graphene, a single layer of carbon atoms arrayed in a repeating, honeycomb-like arrangement.

Graphene's exotic behaviors present intriguing prospects for future technologies, including high-speed, graphene-based electronics that might replace today's silicon-based integrated circuits and other devices. Even at room temperature, electrons in graphene are more than 100 times more mobile than in silicon.

Graphene apparently owes this enhanced mobility to the curious fact that its electrons and other carriers of electric charges behave as though they do not have mass. In conventional materials, the speed of electrons is related to their energy, but not in graphene. Although they do not approach the speed of light, the unbound electrons in graphene behave much like photons, massless particles of light that also move at a speed independent of their energy.

This weird massless behavior is associated with other strangeness. When ordinary conductors are put in a strong magnetic field, charge carriers such as electrons begin moving in circular orbits that are constrained to discrete, equally spaced energy levels. In graphene these levels are known to be unevenly spaced because of the "massless" electrons.

The Georgia Tech/NIST team tracked these massless electrons in action, using a specialized NIST instrument to zoom in on the graphene layer at a billion times magnification, tracking the electronic states while at the same time applying high magnetic fields. The custom-built, ultra-low-temperature and ultra-high-vacuum scanning tunneling microscope allowed them to sweep an adjustable magnetic field across graphene samples prepared at Georgia Tech, observing and mapping the peculiar non-uniform spacing among discrete energy levels that form when the material is exposed to magnetic fields.

The team developed a high-resolution map of the distribution of energy levels in graphene. In contrast to metals and other conducting materials, where the distance from one energy peak to the next is uniformly equal, this spacing is uneven in graphene.

The researchers also probed and spatially mapped graphene's hallmark "zero energy state," a curious phenomenon where the material has no electrical carriers until a magnetic field is applied.

The measurements also indicated that layers of graphene grown and then heated on a substrate of silicon-carbide behave as individual, isolated, two-dimensional sheets. On the basis of the results, the researchers suggest that graphene layers are uncoupled from adjacent layers because they stack in different rotational orientations. This finding may point the way to manufacturing methods for making large, uniform batches of graphene for a new carbon-based electronics.


'/>"/>

Contact: Mark Bello
mark.bello@nist.gov
301-975-3776
National Institute of Standards and Technology (NIST)
Source:Eurekalert

Related biology technology :

1. UM physicists show electrons can travel over 100 times faster in graphene than in silicon
2. Graphene gazing gives glimpse of foundations of universe
3. Graphene used to create worlds smallest transistor
4. Graphene-based gadgets may be just years away
5. By adding graphene, researchers create superior polymer
6. Penn scientists demonstrate potential of graphene films as next-generation transistors
7. Graphene pioneers follow in Nobel footsteps
8. New graphene-based material clarifies graphite oxide chemistry
9. Researchers discover method for mass production of nanomaterial graphene
10. Light-speed nanotech: Controlling the nature of graphene
11. Scientists prove graphenes edge structure affects electronic properties
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:3/22/2017)... March 22, 2017   Boston Biomedical , an ... designed to target cancer stemness pathways, today announced its ... as Chief Executive Officer, effective April 24, 2017. ... J. Li , M.D., FACP, who has led Boston ... Under his leadership, Boston Biomedical has grown from a ...
(Date:3/22/2017)... Grand Bahama (PRWEB) , ... March 21, 2017 , ... ... free educational seminar as part of their live events series, “Stem Cell Therapy: The ... stem cell facility under the 2013 Stem Cell Research and Therapy Act, ...
(Date:3/22/2017)... San Diego, Calif. (PRWEB) , ... March 21, ... ... Frame on Kickstarter , more than tripling its goal and raising over ... and low-maintenance vertical garden that grows nutritious veggies & herbs fast, easy, and ...
(Date:3/22/2017)... CARDIFF, UK (PRWEB) , ... March 21, 2017 , ... ... and tissue oxygenation, is being explored as a way to track the brain’s response ... on tonic pain activation by cold pressor test ,” published today in the ...
Breaking Biology Technology:
(Date:3/22/2017)... Lithuania , March 21, 2017   ... and object recognition technologies, today announced the release ... kit (SDK), which provides improved facial recognition using ... cameras on a single computer. The new version ... to improve accuracy, and it utilizes a Graphing ...
(Date:3/20/2017)... March 20, 2017 At this year,s CeBIT Chancellor ... biometrics manufacturer DERMALOG. The Chancellor came to the DERMALOG stand together with ... this year,s CeBIT partner country. At the largest German biometrics company the ... fingerprint, face and iris recognition as well as DERMALOG´s multi-biometrics system.   ... ...
(Date:3/13/2017)... , March 13, 2017 Future of security: Biometric Face ... ... DERMALOGs Face Matching enables to match face pictures against ... basis to identify individuals. (PRNewsFoto/Dermalog Identification Systems) ... DERMALOG,s "Face Matching" is the fastest software for biometric Face Matching ...
Breaking Biology News(10 mins):