Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Electronics Play By a New Set of Rules at the Molecular Scale

Atomic scale visualization of the single molecule junctions formed with two equivalent pathways (left) and one pathway (right), including the bonding to the tips of two gold electrodes and a schematic of the external electrical circuit.
Atomic scale visualization of the single molecule junctions formed with two equivalent pathways (left) and one pathway (right), including the bonding to the tips of two gold electrodes and a schematic of the external electrical circuit.

Abstract:
In a paper published in Nature Nanontechnology on September 2, 2012, scientists from the U.S. Department of Energy's (DOE) Brookhaven National Laboratory and Columbia University's departments of Chemistry and of Applied Physics explore the laws that govern electronic conductance in molecular scale circuits.

Electronics Play By a New Set of Rules at the Molecular Scale

Upton, NY | Posted on September 2nd, 2012

"Everyone who has worked with basic electronic circuits knows that there are some simple rules of the road, like Ohm's Law," explains collaborator Mark Hybertsen, a physicist at Brookhaven's Center for Functional Nanomaterials (CFN). Hybertsen provided the theory to model the observed circuit behavior with the CFN's computational tools. "For several years we have been asking fundamental questions to probe how those rules might be different if the electronic circuit is shrunk down to the scale of a single molecule."

Conductance measures the degree to which a circuit conducts electricity. In a simple circuit, if you hook the resistors up in parallel, the electrons can flow through two different paths. In this case, the conductance of the full circuit will simply be the sum of the conductance of each resistor.

However, in a molecular circuit, the rules that govern current flow now involve fundamental quantum mechanics. In most single-molecule circuits, the molecules do not behave like conventional resistors; instead, the electrons tunnel through the molecule. When the molecule offers two pathways in parallel, the wave-like movement of an electron can dramatically change the way conductance adds up. For several years, experts in nanotechnology have suspected-but not proven-that quantum interference effects make the conductance of a circuit with two paths up to four times higher than the conductance of a circuit with a single path.

In order to investigate these quantum mechanical effects further, the scientists needed to construct their own controllable nano-size circuits. Working with Ronald Breslow's group at Columbia, they designed and synthesized a series of molecules to use in the experiment.

"Reliably making a circuit from a single molecule is really challenging," says Latha Venkataraman, a Columbia Engineering Applied Physics professor whose group perfected the method used to make the molecular circuits. "Imagine trying to touch the two ends of a molecule that is only ten atoms long."

To make the circuits, Venkataraman's group adapted a scanning tunneling microscope (STM) apparatus to repeatedly press a sharp gold tip into another gold electrode and then pull it away. When this junction breaks, there is a moment when the gap between the two pieces of gold is a perfect fit for the molecule. Once the circuit system is set up, the conductance measurement is fast and can be repeated thousands of times to get statistically reliable data.

Using this approach, the scientists discovered that the molecules with two built-in pathways like the one visualized in the figure at right had a conductance that was greater than the sum of each arm's conductance, although the increase was not as large as they had anticipated. In order to understand this effect better, Columbia's Hector Vasquez worked with Hybertsen to computationally simulate the quantum mechanical transmission of an electron through each circuit.

"Both the measurements and the simulations show that the molecules with two parallel paths can have a conductance that is bigger than two times that of molecule with a single path," said Hybertsen. "This is the signature that the quantum interference effect is playing a role."

The group suspects that other factors, such as the nature of the molecule's bond to the electrodes, need to be considered when calculating the conductance of a molecular circuit. They are currently looking into other central questions about molecular electronics, including how the device changes when different metals are used.

This research was funded primarily by the National Science Foundation and the New York State Office of Science, Technology, and Academic Research. Columbia's Rachid Skouta and Severin Schneebeli synthesized the experiment molecules with Ronald Breslow and Masha Kamanetska carried out the conductance measurements. The CFN at Brookhaven Lab is supported by the DOE's Office of Science.

DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

The Center for Functional Nanomaterials at Brookhaven National Laboratory is one of the five DOE Nanoscale Science Research Centers (NSRCs), premier national user facilities for interdisciplinary research at the nanoscale. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE's Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge and Sandia and Los Alamos national laboratories. For more information about the DOE NSRCs, please visit nano.energy.gov.

####

About Brookhaven National Laboratory
One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

Visit Brookhaven Lab's electronic newsroom for links, news archives, graphics, and more at www.bnl.gov/newsroom, follow Brookhaven Lab on Twitter, http://twitter.com/BrookhavenLab, or like us on Facebook, www.facebook.com/brookhavenlab .

For more information, please click here

Contacts:
Karen McNulty Walsh
(631) 344-8350

or
Peter Genzer
(631) 344-3174

Copyright © Brookhaven National Laboratory

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

$18-million NSF investment aims to take flat materials to new heights: 2-D alternatives to graphene may enable exciting advances in electronics, photonics, sensors and other applications October 1st, 2014

Arrowhead Expands Management Team with Appointment of Susan Boynton as Vice President Global Regulatory Affairs October 1st, 2014

New Absorber Will Lead to Better Biosensor: Biosensors are more sensitive and able to detect smaller changes in the environment October 1st, 2014

Graphene chips are close to significant commercialization October 1st, 2014

Laboratories

Novel approach to magnetic measurements atom-by-atom October 1st, 2014

Imaging

Novel approach to magnetic measurements atom-by-atom October 1st, 2014

Stressed Out: Research Sheds New Light on Why Rechargeable Batteries Fail October 1st, 2014

Govt.-Legislation/Regulation/Funding/Policy

$18-million NSF investment aims to take flat materials to new heights: 2-D alternatives to graphene may enable exciting advances in electronics, photonics, sensors and other applications October 1st, 2014

Novel approach to magnetic measurements atom-by-atom October 1st, 2014

'Stealth' nanoparticles could improve cancer vaccines October 1st, 2014

NREL Announces New Center Directors to lead R&D, Analysis Efforts September 30th, 2014

Chip Technology

$18-million NSF investment aims to take flat materials to new heights: 2-D alternatives to graphene may enable exciting advances in electronics, photonics, sensors and other applications October 1st, 2014

Breakthrough in ALD-graphene by Picosun technology October 1st, 2014

Graphene chips are close to significant commercialization October 1st, 2014

Speed at its limits September 30th, 2014

Discoveries

Breakthrough in ALD-graphene by Picosun technology October 1st, 2014

Novel approach to magnetic measurements atom-by-atom October 1st, 2014

Nanoparticles Accumulate Quickly in Wetland Sediment: Aquatic food chains might be harmed by molecules "piggybacking" on carbon nanoparticles October 1st, 2014

'Stealth' nanoparticles could improve cancer vaccines October 1st, 2014

Announcements

'Stealth' nanoparticles could improve cancer vaccines October 1st, 2014

Stressed Out: Research Sheds New Light on Why Rechargeable Batteries Fail October 1st, 2014

New Absorber Will Lead to Better Biosensor: Biosensors are more sensitive and able to detect smaller changes in the environment October 1st, 2014

Graphene chips are close to significant commercialization October 1st, 2014

Tools

Breakthrough in ALD-graphene by Picosun technology October 1st, 2014

Novel approach to magnetic measurements atom-by-atom October 1st, 2014

Stressed Out: Research Sheds New Light on Why Rechargeable Batteries Fail October 1st, 2014

Yale University and Leica Microsystems Partner to Establish Microscopy Center of Excellence: Yale Welcomes Scientists to Participate in Core Facility Opening and Super- Resolution Workshops October 20 Through 31, 2014 September 30th, 2014

Research partnerships

Novel approach to magnetic measurements atom-by-atom October 1st, 2014

'Stealth' nanoparticles could improve cancer vaccines October 1st, 2014

Stressed Out: Research Sheds New Light on Why Rechargeable Batteries Fail October 1st, 2014

Research mimics brain cells to boost memory power September 30th, 2014

Quantum nanoscience

Rice launches Center for Quantum Materials: RCQM will immerse global visitors in cross-disciplinary research September 30th, 2014

Big Results Require Big Ambitions: Three young UCSB faculty receive CAREER awards from the National Science Foundation September 18th, 2014

Elusive Quantum Transformations Found Near Absolute Zero: Brookhaven Lab and Stony Brook University researchers measured the quantum fluctuations behind a novel magnetic material's ultra-cold ferromagnetic phase transition September 15th, 2014

Layered graphene sandwich for next generation electronics September 8th, 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