Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Magnetism flicks switch on "dark excitons"

Abstract:
Tests At Leading Magnetic Labs Shed Light On Nanotube Mystery

Magnetic Transistor Could "Dial In" Quantum Effects

Houston, TX | Posted on January 10, 2006

In new experimental research appearing in this week's issue of Physical Review Letters, a Rice University-led team of nanoscientists and electrical engineers has flipped the switch on "dark excitons" in carbon nanotubes by placing them inside a strong magnetic field.

The research offers new insight into the fundamental optical properties of semiconducting nanotubes, hollow straw-like molecules of pure carbon. Leading computing companies would like to use nanotubes as optical components in next-generation microchips that are faster, more powerful and more energy efficient.

"Single-walled carbon nanotubes offer engineers the intriguing possibility of building chips where electrical inputs can be converted into light and moved about the chip as optical signals rather than electrical signals," said lead researcher Junichiro Kono, associate professor of electrical and computer engineering at Rice. "Thus far, the poor optical performance of nanotubes - in some cases as few as one in 100,000 incoming photons causes a fluorescent emission - has prevented engineers from developing the technology for applications."

Kono said the new research may help scientists formulate new tests to answer some of the most perplexing questions about the optical properties of nanotubes. For example, scientists are currently debating whether low fluorescence efficiencies in nanotubes arise from the intrinsic physical structure of nanotubes or from external factors like structural defects and impurities. Some of the leading theories have the missing light disappearing into "dark" excitons - odd quantum pairings of electrons and electron "holes" that are forbidden by quantum rules from fluorescing. The new magnetic method of overcoming this dark exciton effect could be used to probe the intrinsic properties of nanotubes and help settle the debate.

The team tested materials in some of the world's most powerful magnetic fields. Experiments were conducted at both the Laboratoire National des Champs Magnétiques Pulsés in Toulouse, France, and at the National High Magnetic Field Laboratory at New Mexico's Los Alamos National Laboratory.

"We hope that our experimental methods will help better inform theorists and ultimately aid in the development of new devices with far superior functions than those based on existing technology," said Sasa Zaric, whose doctoral dissertation will be based on the work.

Nanotubes are a fraction of the size of transistors used in today's best microchips. As electronic components, nanotubes could reduce power demands and heating in next-generation chips. But as optical components they offer far more. The replacement of copper cables with fiberoptics revolutionized the volume and speed of data transmission in the telecom industry 20 years ago, and the parallels in microchips are tantalizing.

The research was funded by the Robert A. Welch Foundation and the National Science Foundation. Rice co-authors include electrical and computer engineering's Sasa Zaric, Gordana Ostojic and Jonah Shaver, and chemistry's Valerie Moore, Robert Hauge and Richard Smalley. Other co-authors include Oliver Portugall, Paul Frings and Geert Rikken, all of the Laboratoire National des Champs Magnétiques Pulsés in Toulouse, France; Madalina Furis and Scott Crooker of the National High Magnetic Field Laboratory at Los Alamos National Laboratory; and Xing Wei of the National High Magnetic Field Laboratory at Florida State University.

####

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

Contact:
Jade Boyd
(713) 348-6778
jadeboyd@rice.edu

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

Possible Futures

Novel 'converter' heralds breakthrough in ultra-fast data processing at nanoscale: Invention bagged four patents and could potentially make microprocessor chips work 1,000 times faster October 20th, 2017

Bringing the atomic world into full color: Researchers turn atomic force microscope measurements into color images October 19th, 2017

'Find the Lady' in the quantum world: International team of researchers presents method for quantum-mechanical swapping of positions October 18th, 2017

Long nanotubes make strong fibers: Rice University researchers advance characterization, purification of nanotube wires and films October 17th, 2017

Nanotubes/Buckyballs/Fullerenes/Nanorods

Long nanotubes make strong fibers: Rice University researchers advance characterization, purification of nanotube wires and films October 17th, 2017

How to draw electricity from the bloodstream: A one-dimensional fluidic nanogenerator with a high power-conversion efficiency September 11th, 2017

Silk could improve sensitivity, flexibility of wearable body sensors August 20th, 2017

Regulation of two-dimensional nanomaterials: New driving force for lithium-ion batteries July 26th, 2017

Nanoelectronics

Nanometrics Announces Preliminary Results for the Third Quarter of 2017: Quarterly Results Impacted by Delays in Revenue Recognition on Multiple Systems into Japan October 12th, 2017

Seeing the next dimension of computer chips: Researchers image perfectly smooth side-surfaces of 3-D silicon crystals with a scanning tunneling microscope, paving the way for smaller and faster computing devices October 11th, 2017

Columbia engineers invent breakthrough millimeter-wave circulator IC October 6th, 2017

Tungsten offers nano-interconnects a path of least resistance: Crystalline tungsten shows insight and promise in addressing the challenges of electrical interconnects that have high resistivity at the nanoscale October 4th, 2017

Announcements

Arrowhead Presents Promising Preclinical Data on Development of ARO-AAT for Treatment of Alpha-1 Liver Disease at Liver Meeting(R) 2017 October 23rd, 2017

A step closer to understanding quantum mechanics: Swansea University’s physicists develop a new quantum simulation protocol October 22nd, 2017

Creation of coherent states in molecules by incoherent electrons October 21st, 2017

Leti Coordinating Project to Develop Innovative Drivetrains for 3rd-generation Electric Vehicles: CEA Tech’s Contribution Includes Liten’s Knowhow in Magnetic Materials and Simulation And Leti’s Expertise in Wide-bandgap Semiconductors October 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