Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Nanotube flickering reveals single-molecule rendezvous

Abstract:
In this week's issue of Science, French and U.S. researchers describe a new technique that allowed them to zoom in and observe quantum quasiparticles called excitons on individual carbon nanotubes. The team, which was led by Rice University chemist Bruce Weisman and University of Bordeaux physicist Laurent Cognet, found that each exciton travels about 90 nanometers and visits around 10,000 carbon atoms during its 100-trillionth-of-a-second lifespan.

Nanotube flickering reveals single-molecule rendezvous

Houston, TX | Posted on June 7th, 2007

In the quantum world, photons and electrons dance, bump and carry out transactions that govern everything we see in the world around us. In this week's issue of Science, French and U.S. scientists describe a new technique in nanotechnology that allowed them to zoom in -- way in -- and observe those quantum transactions on a single DNA-sized carbon molecule called a nanotube.

The team, led by Rice University chemist Bruce Weisman and University of Bordeaux physicist Laurent Cognet, focused on short-lived quantum oddities called "excitons," which are created when light hits a semiconductor.

"Excitons in carbon nanotubes only last about 100 trillionths of a second," Weisman said. "They wink out of existence when the nanotube emits a photon of fluorescent light, but during their short lifetimes they can move around."

To study exciton mobility on nanotubes, Cognet and his co-workers conducted experiments during a sabbatical visit to Weisman's lab at Rice in early 2007. They used a fluorescence microscope to observe tiny sections of individual nanotubes less than a micrometer long. The nanotubes were held still in a soft liquid gel. By shining light on them while introducing acids and other chemicals into the gel, the team was able to observe reactions that would quench, or kill, any passing excitons. To do this, they used a time-lapse infrared camera to capture the fluorescent glow from the nanotube about 20 times a second. They then compiled records that revealed the characteristic steps that are the signature of exciton quenching by single molecules.

"We found that each nanotube exciton travels about 90 nanometers and visits some 10,000 carbon atoms during its lifespan," Cognet said.

Excitons are "quasiparticles" created when a photon strikes a semiconductor and excites an electron to a higher energy level. The electron leaves behind a positively charged void called a "hole." That hole pairs with the electron to form the exciton, which takes on a life of its own that ends abruptly when it emits a photon or becomes quenched.

Cognet said the unusual electronic properties of carbon nanotubes made them a unique system to observe single-molecule reactions.

"Nanotubes provided us a very stable baseline for our measurements," he said. "No other light-emitting molecules have the properties that we needed for this experiment."

Weisman helped found the field of nanotube spectroscopy with the 2002 discovery of nanotube fluorescence and subsequent research that classified the light signatures of dozens of types of semiconducting nanotubes.

"I was impressed at the speed and quality of the work that Dr. Cognet and the team produced during this project," said Weisman, professor of chemistry. "His visit to Rice has been extremely productive."

Research co-authors include: James Tour, Chao Professor of Chemistry; Dmitri Tsyboulski, Evans Attwell Postdoctoral Fellow; and graduate students John-David Rocha and Condell Doyle.

The research was funded by CNRS (France), the Fulbright Foundation, the Welch Foundation, NASA, Applied NanoFluorescence, LLC, the National Science Foundation, Rice's Center for Biological and Environmental Nanotechnology, and the Rice-Houston Alliance for Graduate Education and the Professoriate.

####

About Rice University
Rice University is consistently ranked one of America’s best teaching and research universities. It is distinguished by its: size—2,850 undergraduates and 1,950 graduate students; selectivity—10 applicants for each place in the freshman class; resources—an undergraduate student-to-faculty ratio of 6-to-1, and the fifth largest endowment per student among American universities; residential college system, which builds communities that are both close-knit and diverse; and collaborative culture, which crosses disciplines, integrates teaching and research, and intermingles undergraduate and graduate work. Rice’s wooded campus is located in the nation’s fourth largest city and on America’s South Coast.

For more information, please click here

Contacts:
Jade Boyd
713-348-6778

Copyright © Rice University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Nanotubes/Buckyballs/Fullerenes/Nanorods

Killing cancer in the heat of the moment: A new method efficiently transfers genes into cells, then activates them with light. This could lead to gene therapies for cancers July 9th, 2017

Tests show no nanotubes released during utilisation of nanoaugmented materials June 9th, 2017

Ag/ZnO-Nanorods Schottky diodes based UV-PDs are fabricated and tested May 26th, 2017

Fed grant backs nanofiber development: Rice University joins Department of Energy 'Next Generation Machines' initiative May 10th, 2017

Discoveries

Shining rings: A new material emits white light when exposed to electricity: New synthetic approach could spark development of other dynamic materials July 24th, 2017

Scientists announce the quest for high-index materials: All-dielectric nanophotonics: The quest for better materials and fabrication techniques July 22nd, 2017

Pulses of electrons manipulate nanomagnets and store information: Scientists use electron pulses to create and manipulate nanoscale magnetic excitations that can store data July 21st, 2017

The first light atomic nucleus with a second face July 20th, 2017

Announcements

Shining rings: A new material emits white light when exposed to electricity: New synthetic approach could spark development of other dynamic materials July 24th, 2017

Ultrathin device harvests electricity from human motion July 23rd, 2017

The July 23 close fly-by of asteroid 2017 BS5 is explored in a Q&A with Dr. John S. Lewis, chief scientist at Deep Space Industries July 23rd, 2017

Scientists announce the quest for high-index materials: All-dielectric nanophotonics: The quest for better materials and fabrication techniques July 22nd, 2017

Quantum nanoscience

Carbon displays quantum effects July 13th, 2017

Physicists make quantum leap in understanding life's nanoscale machinery June 27th, 2017

Atomic imperfections move quantum communication network closer to reality June 25th, 2017

Oxford Instruments congratulates Lancaster University for inaugurating the IsoLab, built for studying quantum systems June 20th, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project