Free Newsletters - Space News - Defense Alert - Environment Report - Energy Monitor
. 24/7 Space News .




NANO TECH
Scientists delve deeper into carbon nanotubes
by Belle Dume for Institute of Physics
London, UK (SPX) Feb 25, 2013


One, two, and three walls of carbon.

The outer walls of both double- and triple-walled carbon nanotubes (CNTs) protect the innermost tubes from interacting with their environment. That is the key finding of a study by researchers in the US, Germany and Japan, who have made the first detailed examination of triple-walled CNTs using resonant Raman spectroscopy. The protection afforded by the outer layer allows the tiny tubes to be studied in more detail than ever before, which could be a boon to those using CNTs to create new technologies.

A single-walled carbon nanotube (SWCNT) resembles a tiny drinking straw with a wall that is just one carbon atom thick. A double-walled carbon nanotube (DWCNT) consists of two concentric SWCNTs coupled together by weak Van der Waals interactions. The inner and outer tubes can either be semiconducting or metallic. However, because the outer tube is in direct contact with its environment, it can be difficult to obtain accurate information about its fundamental physical properties.

Third wall protects the second
To gain a better understanding of the outer tube in a DWCNT, Thomas Hirschmann and Paulo Araujo at the Massachusetts Institute of Technology and colleagues studied individual and bundled triple-walled carbon nanotubes (TWCNTs). A TWCNT can be thought of as a DWCNT wrapped around a SWCNT. The researchers found that the extra outer tube protects the two inner ones from interacting with their environment, thus allowing them to be studied more accurately. An unrolled TWCNT can be thought of as a trilayer graphene ribbon, and has all the outstanding electronic and mechanical properties that this carbon material boasts.

The team was led by MIT's Mildred Dresselhaus and included scientists from the University of Hamburg, the Nagaoka University of Technology and Shinshu University. The researchers used a very fast yet sensitive Raman spectrometer, which allowed them to detect and characterize the same individual TWCNT with different laser lines under identical experimental conditions. "Only a few groups in the world are equipped with such an instrument capable of characterizing individual CNTs in this way," said Hirschmann.

Wall-to-wall measurements
"The analyses allowed us to study fundamental properties such as intertube mechanical coupling, wall-to-wall (WtW) distance, metallicity and curvature-dependent intertube interactions," he explained. "Such knowledge will be of fundamental importance for technological applications that exploit these nanostructures."

The researchers characterized five individual TWCNTs in detail and found that the WtW distance between the inner two tubes in all the samples ranges from 0.323 to 0.337 nm. These values are larger than the WtW distance observed in previously studied DWCNTs (0.284-0.323 nm). The distances are also closer to the interlayer distance in graphene (0.335 nm).

"We also found that the intertube interactions affect innermost nanotubes differently, according to which metallicity they have, and that the elusive mechanical coupling between the 'radial breathing mode', or RBM, of concentric nanotubes does not exist, even for relatively short WtW distances of 0.323 nm," added Hirschmann. "This is an important finding and shows that, although the TWCNTs are hybrid systems, the tubes themselves are mostly independent of one another."

Wealth of information
The RBM is the most important spectroscopic signature of a CNT, the frequency of vibration of which is known to be inversely proportional to the tube diameter, he explained. These so-called first-order Raman features provide a wealth of information on the electronic and vibrational structure of these nanomaterials.

"Our analyses also shed more light on the Van der Waals forces mediating the interactions in concentric ordered CNTs, such as DWCNTs and TWCNTs," said Araujo. "These low-energy interactions are important for technology applications because they affect the electronic and vibrational properties of the tubes."

The team is now busy analysing shielding phenomena and intertube interaction effects in multi-walled carbon-nanotube systems. Here, intertube interactions not only affect the measured RBMs but also other Raman features. "One of our main goals is to find better conditions in which to grow CNTs by controlling interactions between nanotubes walls," said Hirschmann. "To this end, we are working closely with Yoong Ahm Kim and colleagues at Shinshu University, who are experts when it comes to synthesizing these nanomaterials."

The research is described in ACS Nano.

.


Related Links
Institute of Physics
Nano Technology News From SpaceMart.com
Computer Chip Architecture, Technology and Manufacture






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





NANO TECH
Nano-machines for 'bionic proteins'
Vienna, Austria (SPX) Feb 21, 2013
Physicists of the University of Vienna together with researchers from the University of Natural Resources and Life Sciences Vienna developed nano-machines which recreate principal activities of proteins. They present the first versatile and modular example of a fully artificial protein-mimetic model system, thanks to the Vienna Scientific Cluster (VSC), a high performance computing infrastructur ... read more


NANO TECH
Water On The Moon: It's Been There All Along

Building a lunar base with 3D printing

US, Europe team up for moon fly-by

Russia to Launch Lunar Mission in 2015

NANO TECH
Mars rover ingests rock powder for tests

Opportunity Is On A Rock Hunt

Big Nickel Rock Target Ahead

NASA Rover Confirms First Drilled Mars Rock Sample

NANO TECH
Choreographed to Perfection

ATK Launch Abort Motor For First Orion Test Vehicle

Supersonic skydiver's records confirmed

Kennedy Engineers Designing Plant Habitat For ISS

NANO TECH
Welcome Aboard Shenzhou 10

Reshuffle for Tiangong

China to launch 20 spacecrafts in 2013

Mr Xi in Space

NANO TECH
Record Number of Students Control ISS Camera

NASA briefly loses contact with space station

Temporary Comm Loss Interrupts Crew's Day

Low-Gravity Flights Will Aid ISS Fluids and Combustion Experiments

NANO TECH
SpaceX 2 Launch Set for March 1

NASA Releases Glory Taurus XL Launch Failure Report Summary

India's 102nd space mission lifts off successfully

Countdown begins for Indo-French satellite launch

NANO TECH
NASA's Kepler Mission Discovers Tiny Planet System

Kepler helps astronomers find tiny exo planet

Searching for a Pale Blue SPHERE in the Universe

Earth-like planets are right next door

NANO TECH
Tokyo hotel shrinks in new-style urban demolition

Fluids in Space, Shaken Not Stirred

The world's most sensitive plasmon resonance sensor inspired by ancient Roman cup

Sustainable new catalysts fueled by a single proton




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement