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 Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

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 lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>