Navigation Links
Heavier hydrogen on the atomic scale reduces friction
Date:11/2/2007

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.

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 defect, 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.


'/>"/>

Contact: Steve McGregor
smcgregor@anl.gov
630-252-5580
DOE/Argonne National Laboratory
Source:Eurekalert

Related biology technology :

1. Preparative Nondenaturing Gel Electrophoresis to Purify NADP-Specific Glutamate Dehydrogenase From Chlorella, Rev B
2. Virent enters agreement with Shell Oil unit to make hydrogen with biomass
3. Virent gets $1.4 million investment for its hydrogen technology
4. UW students compete to make hydrogen cars, other renewable projects
5. Modine Manufacturing makes hydrogen generator with ChevronTexaco
6. Virent receives $2 million boost for hydrogen energy research
7. UW engineers clear bottleneck in hydrogen production
8. Virent shows off its hydrogen-fuel plans
9. Kodak in vivo imaging system: precise coregistration of molecular imaging with anatomical X-ray imaging in animals
10. Imago provides atomic probe to Australian lab
11. Ni-NTA Superflow Columns - automated large-scale purification of 6xHis-tagged proteins
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:11/30/2016)... Nov. 30, 2016  GenomOncology today announced the appointment of ... Medical Affairs.  Dr. Coleman will oversee clinical ... proprietary knowledge-enabled platform. The GenomOncology software suite empowers molecular pathologists ... data and clinical decision support, from quality control through reporting. ... , , ...
(Date:11/30/2016)... VANCOUVER , Nov. 30, 2016 /PRNewswire/ -  Equicare ... coordination solutions, has been recognized as one of the ... 100, an annual international listing that distinguishes the top ... "We,ve pushed a great step forward this year continually ... growing our own customer base and team," says ...
(Date:11/30/2016)... 30, 2016   Merck , a leading science ... into a set of agreements with Evotec AG, whereby ... of genetic reagents such as CRISPR and shRNA libraries. ... offers an accelerated pathway to explore and identify new ... identification of new targets, a process that can be ...
(Date:11/30/2016)... ... 2016 , ... With growth rates averaging more than 30% each year, Random42 ... to continuing their expansion in their new office space. The new office has a ... by the creative industries, so Random42 Scientific Communication will fit right in. , ...
Breaking Biology Technology:
(Date:6/15/2016)... 15, 2016 Transparency Market ... Recognition Market by Application Market - Global Industry Analysis Size ... to the report, the  global gesture recognition market ... and is estimated to grow at a CAGR ... 2024.  Increasing application of gesture recognition ...
(Date:6/7/2016)... 7, 2016  Syngrafii Inc. and San Antonio ... that includes integrating Syngrafii,s patented LongPen™ eSignature "Wet" ... collaboration will result in greater convenience for SACU ... while maintaining existing document workflow and compliance requirements. ... Highlights: ...
(Date:6/2/2016)... 2, 2016   The Weather Company , an IBM ... an industry-first capability in which consumers will be able to ... ask questions via voice or text and receive relevant information ... Marketers have long sought an advertising solution that ... be personal, relevant and valuable; and can scale across millions ...
Breaking Biology News(10 mins):