Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Rice deciphers optical spectra of carbon nanotubes

29.11.2002


Study opens door for faster, simpler methods of measuring carbon nanotubes


This three-dimensional plot of light-emission intensity of carbon nanotubes shows a peak for each "species" of light-emitting nanotube, indicating that each "species" has a unique optical signature. Variations in signature are due to slight differences in nanotube structure and diameter. Emission intensity is plotted as a function of excitation wavelength and emission wavelength



Building upon this summer’s groundbreaking finding that carbon nanotubes are fluorescent, chemists at Rice University have precisely identified the optical signatures of 33 "species" of nanotubes, establishing a new methodology for assaying nanotubes that is simpler and faster than existing methods.

In research published this week by Science magazine, a spectroscopy research team led by Rice Chemistry Professor R. Bruce Weisman detailed the wavelengths of light that are absorbed and emitted by each type of light-emitting nanotube. The findings hold great promise for chemists, physicists and materials scientists studying nanotubes, because it otherwise takes many hours of tedious testing for researchers to assay a single sample of nanotubes, and optical tests could be much faster and simpler.


"Optical nanotube spectroscopy is an important enabling tool for nanotechnology research, because it reveals the composition of nanotube samples through simple measurements," said Weisman. "Chemists and biochemists commonly use optical instruments that can characterize samples within a matter of seconds. With refinement, similar methodologies can probably be applied to nanotube analysis."

Carbon nanotubes are cylinders of carbon atoms that measure about one nanometer, or one-billionth of a meter, in diameter. That’s about 50,000 times smaller than a human hair. Because of their astounding physical and electrical properties, scientists have envisioned using nanotubes in everything from the skins of spacecraft to electronic wiring that’s 100 times smaller than the circuits in today’s most advanced silicon microchips.

The ability to sort nanotubes must be overcome if they are to be transformed from a laboratory oddity to a marketable commodity, but sorting isn’t feasible until chemists have a practical way to inspect what they’re sorting. Sorting is an issue because nanotubes aren’t identical. There are actually three families of carbon nanotubes, and cousins and siblings in these families have slightly different diameters and physical structures. While almost imperceptible, these slight variations give rise to drastically different properties: about one-third of nanotubes are metals for example, and the others are semiconductors. Since every method of preparing nanotubes yields dozens of varieties, researchers have to sort and classify the types of tubes they are most interested in studying.

This summer, Weisman’s group and the carbon nanotube research team of Rice’s Richard Smalley reported that all semiconducting varieties of nanotubes fluoresce. Fluorescence occurs when a substance absorbs one wavelength of light and emits a different wavelength in response.

Once fluorescence of nanotubes was confirmed, researchers in Weisman’s and Smalley’s research groups began investigating the spectral properties of various kinds and classes of nanotubes. The research is detailed in a paper titled "Structure-Assigned Optical Spectra of Single-Walled Carbon Nanotubes," published online today by Science magazine.

In addition to applied researchers, theoretical scientists will also use the spectral research to help refine models that predict the expected physical, mechanical, structural and electrical properties of nanotubes. In several instances, Weisman’s group reported experimental data that differed substantially from what theorists have predicted.


###
The Rice research team also included Sergei M. Bachilo, Michael S. Strano, Carter Kittrell, Robert H. Hauge and Smalley. The research was funded by the National Science Foundation and the Robert A. Welch Foundation.

Jade Boyd | EurekAlert!
Further information:
http://chico.rice.edu/

More articles from Life Sciences:

nachricht New technique unveils 'matrix' inside tissues and tumors
29.06.2017 | University of Copenhagen The Faculty of Health and Medical Sciences

nachricht Designed proteins to treat muscular dystrophy
29.06.2017 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making Waves

Computer scientists use wave packet theory to develop realistic, detailed water wave simulations in real time. Their results will be presented at this year’s SIGGRAPH conference.

Think about the last time you were at a lake, river, or the ocean. Remember the ripples of the water, the waves crashing against the rocks, the wake following...

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Nanostructures taste the rainbow

29.06.2017 | Physics and Astronomy

New technique unveils 'matrix' inside tissues and tumors

29.06.2017 | Life Sciences

Cystic fibrosis alters the structure of mucus in airways

29.06.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>