Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Heavier hydrogen on the atomic scale reduces friction

This hot filament chemical vapor deposition (HFCVD) system is used for the hydrogen and deuterium termination of diamond surfaces.
This hot filament chemical vapor deposition (HFCVD) system is used for the hydrogen and deuterium termination of diamond surfaces.

Abstract:
Scientists may be one step closer to understanding the atomic forces that cause friction, thanks to a recently published study by researchers from the University of Pennsylvania, the University of Houston and the U.S. Department of Energy's Argonne National Laboratory.

Heavier hydrogen on the atomic scale reduces friction

ARGONNE, IL | Posted on November 3rd, 2007

The research, led by Robert Carpick of the University of Pennsylvania, found a significant difference in friction exhibited by diamond surfaces that had been coated with different isotopes of hydrogen and then rubbed against a small carbon-coated tip.

Scientists lack a comprehensive model of friction on the nanoscale and only generally grasp its atomic-level causes, which range from local chemical reactions to electronic interactions to phononic, or vibrational, resonances.

To investigate the latter, Argonne scientist Anirudha Sumant and his colleagues used single-crystal diamond surfaces coated with layers of either atomic hydrogen or deuterium, a hydrogen atom with an extra neutron. The deuterium-terminated diamonds had lower friction forces because of their lower vibrational frequencies, an observation that Sumant attributed to that isotope's larger mass. They have also observed same trend on a silicon substrate, which is structurally similar to that of diamond.

Previous attempts to make hydrogen-terminated diamond surfaces relied on the use of plasmas, which tended to etch the material.

"When you're looking at such a small isotopic effect, an objectively tiny change in the mass, you have to be absolutely sure that there are no other complicating effects caused by chemical or electronic interferences or by small topographic variations," Sumant said. "The nanoscale roughening of the diamond surface from the ion bombardment during the hydrogen or deuterium termination process, even though it was at very low level, remained one of our principal concerns."

Sumant and his collaborators had looked at a number of other ways to try to avoid etching, even going to such lengths as to soak the films in olive oil before applying the hydrogen layers. However, no method had provided a smooth, defect-free hydrogen layer with good coverage that would avoid generating background noise, he said.

However, while performing work at the University of Wisconsin-Madison, Sumant developed a system for depositing diamond thin films. The technique, called hot filament chemical vapor deposition, involves the heating of a tungsten filament (like those found in incandescent light bulbs) to over 2000 degrees Celsius.

If the diamond film is exposed to a flow of molecular hydrogen while sitting within a centimeter of the hot filament, the heat will cause the molecular hydrogen to break down into atomic hydrogen, which will react with the film's surface to create a perfectly smooth layer. Since this method does not require the use of plasma, there is no danger of ion-induced etching.

"We've proved that this is a gentler method of terminating a diamond surface," Sumant said.

Sumant said that he hopes to use the knowledge gained from the experiment to eventually discover a way to manipulate the friction of surfaces on the atomic level. Such a result would prove immensely valuable to the development of nanoelectromechanical systems, or NEMS, based on diamonds, one of Sumant's primary research interests at Argonne's Center for Nanoscale Materials.

The paper, "Nanoscale Friction Varied by Isotopic Shifting of Surface Vibrational Frequencies," appears in the November 2 issue of Science.

The research was supported by the National Science Foundation, an NSF Graduate Research Fellowship, the Air Force Office of Scientific Research and the Department of Energy's Office of Science, Office of Basic Energy Sciences.

By Jared Sagoff.

####

About Argonne National Laboratory
Argonne National Laboratory, a renowned R&D center, brings the world's brightest scientists and engineers together to find exciting and creative new solutions to pressing national problems in science and technology. The nation's first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America 's scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy's Office of Science.

About The Center for Nanoscale Materials

The Center for Nanoscale Materials at Argonne National Laboratory is a joint partnership between the U.S. Department of Energy (DOE) and the State of Illinois, as part of DOE'S Nanoscale Science Research Center program. The CNM serves as a user-based center, providing tools and infrastructure for nanoscience and nanotechnology research. The CNM's mission includes supporting basic research and the development of advanced instrumentation that will help generate new scientific insights and create new materials with novel properties. The existence of the CNM, with its centralized facilities, controlled environments, technical support, and scientific staff, enabled researchers to excel and significantly extend their reach.

For more information, please click here

Contacts:
Steve McGregor
630/252-5580

Copyright © Argonne 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

Discoveries

Mysteries of ‘Molecular Machines’ Revealed: Phenix software uses X-ray diffraction spots to produce 3-D image December 22nd, 2014

New non-invasive method can detect Alzheimer's disease early: MRI probe technology shows brain toxins in living animals for first time December 22nd, 2014

Piezoelectricity in a 2-D semiconductor: Berkeley Lab researchers discovery of piezoelectricty in molybdenum disulfide holds promise for future MEMS December 22nd, 2014

Enzyme Biosensor Used for Rapid Measurement of Drug December 22nd, 2014

Materials/Metamaterials

Aculon Hires New Business Development Director December 19th, 2014

ORNL microscopy pencils patterns in polymers at the nanoscale December 17th, 2014

Pb islands in a sea of graphene magnetise the material of the future December 16th, 2014

Graphene Applied in Production of Recyclable Electrodes December 13th, 2014

Announcements

New non-invasive method can detect Alzheimer's disease early: MRI probe technology shows brain toxins in living animals for first time December 22nd, 2014

Piezoelectricity in a 2-D semiconductor: Berkeley Lab researchers discovery of piezoelectricty in molybdenum disulfide holds promise for future MEMS December 22nd, 2014

Quantum physics just got less complicated December 22nd, 2014

Enzyme Biosensor Used for Rapid Measurement of Drug December 22nd, 2014

Research partnerships

New non-invasive method can detect Alzheimer's disease early: MRI probe technology shows brain toxins in living animals for first time December 22nd, 2014

Quantum physics just got less complicated December 22nd, 2014

Scientists reveal breakthrough in optical fiber communications December 21st, 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

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