|
Researchers measure carbon nanotube interaction
October 17, 2007LIVERMORE, Calif. - Carbon nanotubes have been employed for a variety of uses including composite materials, biosensors, nano-electronic circuits and membranes.
While they have proven useful for these purposes, no one really knows much about what's going on at the molecular level. For example, how do nanotubes and chemical functional groups interact with each other on the atomic scale" Answering this question could lead to improvements in future nano devices.
In a quest to find the answer, researchers for the first time have been able to measure a specific interaction for a single functional group with carbon nanotubes using chemical force microscopy - a nanoscale technique that measures interaction forces using tiny spring-like sensors. Functional groups are the smallest specific group of atoms within a molecule that determine the characteristic chemical reactions of that molecule.
A recent report by a team of Lawrence Livermore National Laboratory researchers and colleagues found that the interaction strength does not follow conventional trends of increasing polarity or repelling water. Instead, it depends on the intricate electronic interactions between the nanotube and the functional group.
"This work pushes chemical force microscopy into a new territory," said Aleksandr Noy, lead author of the paper that appears in the Oct. 14 online issue of the journal, Nature Nanotechnology.
Understanding the interactions between carbon nanotubes (CNTs) and individual chemical functional groups is necessary for the engineering of future generations of sensors and nano devices that will rely on single-molecule coupling between components. Carbon nanotubes are extremely small, which makes it particularly difficult to measure the adhesion force of an individual molecule at the carbon nanotube surface. In the past, researchers had to rely on modeling, indirect measurements and large microscale tests.
But the Livermore team went a step further and smaller to get a more exact measurement. The scientists were able to achieve a true single function group interaction by reducing the probe-nanotube contact area to about 1.3 nanometers (one million nanometers equals one millimeter).
Adhesion force graphs showed that the interaction forces vary significantly from one functionality to the next. To understand these measurements, researchers collaborated with a team of computational chemists who performed ab initio simulations of the interactions of functional groups with the sidewall of a zig-zag carbon nanotube. Calculations showed that there was a strong dependence of the interaction strength on the electronic structure of the interacting molecule/CNT system. To the researchers delight, the calculated interaction forces provided an exact match to the experimental results.
"This is the first time we were able to make a direct comparison between an experimental measurement of an interaction and an ab initio calculation for a real-world materials system," Noy said. "In the past, there has always been a gap between what we could measure in an experiment and what the computational methods could do. It is exciting to be able to bridge that gap."
This research opens up a new capability for nanoscale materials science. The ability to measure interactions on a single functional group level could eliminate much of the guess work that goes into the design of new nanocomposite materials, nanosensors, or molecular assemblies, which in turn could help in building better and stronger materials, and more sensitive devices and sensors in the future.
DOE/Lawrence Livermore National Laboratory
A recent report by a team of Lawrence Livermore National Laboratory researchers and colleagues found that the interaction strength does not follow conventional trends of increasing polarity or repelling water. Instead, it depends on the intricate electronic interactions between the nanotube and the functional group.
"This work pushes chemical force microscopy into a new territory," said Aleksandr Noy, lead author of the paper that appears in the Oct. 14 online issue of the journal, Nature Nanotechnology.
Understanding the interactions between carbon nanotubes (CNTs) and individual chemical functional groups is necessary for the engineering of future generations of sensors and nano devices that will rely on single-molecule coupling between components. Carbon nanotubes are extremely small, which makes it particularly difficult to measure the adhesion force of an individual molecule at the carbon nanotube surface. In the past, researchers had to rely on modeling, indirect measurements and large microscale tests.
But the Livermore team went a step further and smaller to get a more exact measurement. The scientists were able to achieve a true single function group interaction by reducing the probe-nanotube contact area to about 1.3 nanometers (one million nanometers equals one millimeter).
Adhesion force graphs showed that the interaction forces vary significantly from one functionality to the next. To understand these measurements, researchers collaborated with a team of computational chemists who performed ab initio simulations of the interactions of functional groups with the sidewall of a zig-zag carbon nanotube. Calculations showed that there was a strong dependence of the interaction strength on the electronic structure of the interacting molecule/CNT system. To the researchers delight, the calculated interaction forces provided an exact match to the experimental results.
"This is the first time we were able to make a direct comparison between an experimental measurement of an interaction and an ab initio calculation for a real-world materials system," Noy said. "In the past, there has always been a gap between what we could measure in an experiment and what the computational methods could do. It is exciting to be able to bridge that gap."
This research opens up a new capability for nanoscale materials science. The ability to measure interactions on a single functional group level could eliminate much of the guess work that goes into the design of new nanocomposite materials, nanosensors, or molecular assemblies, which in turn could help in building better and stronger materials, and more sensitive devices and sensors in the future.
DOE/Lawrence Livermore National Laboratory
Carbon Nanotubes News and Current Carbon Nanotubes Events RSSLLNL researchers peer into water in carbon nanotubes
Researchers have identified a signature for water inside single-walled carbon nanotubes, helping them understand how water is structured and how it moves within these tiny channels.
The fight for the best quantum bit (qubit)
Our results give us, for the first time, the possibility to understand the interaction between just two electrons placed next to each other in a carbon nanotube.
Perfecting a solar cell by adding imperfections
Nanotechnology is paving the way toward improved solar cells. New research shows that a film of carbon nanotubes may be able to replace two of the layers normally used in a solar cell, with improved performance at a lower cost. Researchers have found a surprising way to give the nanotubes the properties they need: add defects.
Secret ingredient: nanoparticles aid bone growth
In the first study of its kind, bioengineers and bioscientists at Rice University and Radboud University in Nijmegen, Netherlands, have shown they can grow denser bone tissue by sprinkling stick-like nanoparticles throughout the porous material used to pattern the bone.
NASA Scientists Pioneer Method for Making Giant Lunar Telescopes
Scientists working at NASA's Goddard Space Flight Center in Greenbelt, Md., have concocted an innovative recipe for giant telescope mirrors on the Moon. To make a mirror that dwarfs anything on Earth, just take a little bit of carbon, throw in some epoxy, and add lots of lunar dust.
Brown researchers work toward ending cartilage loss
Scientists have long wrestled with how to aid those who suffer cartilage damage and loss. One popular way is to inject an artificial gel that can imitate cartilage's natural ability to act as the body's shock absorber. But that solution is temporary, requiring follow-up injections.
Nanoparticles assemble by millions to encase oil drops
In a development that could lead to new technologies for cleaning up oil spills and polluted groundwater, scientists at Rice University have shown how tiny, stick-shaped particles of metal and carbon can trap oil droplets in water by spontaneously assembling into bag-like sacs.
Carbon nanoribbons could make smaller, speedier computer chips
Stanford chemists have developed a new way to make transistors out of carbon nanoribbons. The devices could someday be integrated into high-performance computer chips to increase their speed and generate less heat, which can damage today's silicon-based chips when transistors are packed together tightly.
Spin control: New technique sorts nanotubes by length
Researchers at the National Institute of Standards and Technology (NIST) have reported a new technique to sort batches of carbon nanotubes by length using high-speed centrifuges.
Go Speed Racer! Revving up the world's fastest nanomotors
In a "major step" toward a practical energy source for powering tomorrow's nanomachines, researchers in Arizona report development of a new generation of sub-microscopic nanomotors that are up to 10 times more powerful than existing motors. Their study is scheduled for the May 27 issue of ACS Nano, a monthly journal.
More Carbon Nanotubes News Articles
| © 2008 BrightSurf.com |