Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Scientists scale terahertz peaks in nanotubes: Rice U. researchers find plasmonic root of terahertz signals in some carbon nanotubes

The ability to sort carbon nanotubes by type through a process called “density gradient ultracentrifugation (DGU)” allowed Rice researchers to test purified batches of nanotubes to find the cause of terahertz peaks in spectroscopic experiments. They determined that free electrons formed plasmons that ripple at terahertz frequencies in metallic and doped nanotubes.Credit: Kono Laboratory/Rice University
The ability to sort carbon nanotubes by type through a process called “density gradient ultracentrifugation (DGU)” allowed Rice researchers to test purified batches of nanotubes to find the cause of terahertz peaks in spectroscopic experiments. They determined that free electrons formed plasmons that ripple at terahertz frequencies in metallic and doped nanotubes.

Credit: Kono Laboratory/Rice University

Abstract:
Carbon nanotubes carry plasmonic signals in the terahertz range of the electromagnetic spectrum, but only if they're metallic by nature or doped.

Scientists scale terahertz peaks in nanotubes: Rice U. researchers find plasmonic root of terahertz signals in some carbon nanotubes

Houston, TX | Posted on December 9th, 2013

In new research, the Rice University laboratory of physicist Junichiro Kono disproved previous theories that dominant terahertz response comes from narrow-gap semiconducting nanotubes.

Knowing that metallic or doped nanotubes respond with plasmonic waves at terahertz frequencies opens up the possibility that the tubes can be used in a wide array of optoelectronic amplifiers, detectors, polarizers and antennas.

The work by Kono and his Rice colleagues appeared online recently in the American Chemical Society journal Nano Letters.

Scientists have long been aware of a terahertz peak in nanotubes, the tiny cylinders of rolled-up carbon that show so much promise for advanced materials. But experiments on batches of nanotubes, which generally grow in a willy-nilly array of types, failed to reveal why it was there.

The origin of the peak was not explainable because researchers were only able to experiment on mixed batches of nanotube types, said Qi Zhang, a graduate student in Kono's group and lead author of the paper. "All the previous work was done with a mixture of semiconducting and metallic tubes. We are the first to clearly identify the plasmonic nature of this terahertz response," he said.

Rice's growing expertise in separating nanotubes by type allowed Kono and his group to test for terahertz peaks in batches of pure metallic nanotubes known as "armchairs" as well as nonmetallic, semiconducting tubes.

"Metallic carbon nanotubes are expected to show plasmon resonance in the terahertz and infrared range, but no group has clearly demonstrated the existence of plasmons in carbon nanotubes," Zhang said. "Previously, people proposed one possible explanation -- that the terahertz peak is due to interband absorption in the small band gaps in semiconducting nanotubes. We rejected that in this paper."

Plasmons are free electrons on the surface of metals like gold, silver or even aluminum nanoparticles that, when triggered by a laser or other outside energy, ripple like waves in a pond. Strong waves can trigger plasmon responses in adjacent nanoparticles. They are being investigated at Rice and elsewhere for use in sophisticated electronic and medical applications.

The Kono group's research showed plasmons rippling at terahertz frequencies only along the length of a nanotube, but not across its width. "The only way charge carriers can move around is in the long direction," Kono said. The researchers previously used this fact to demonstrate that aligned carbon nanotubes act as an excellent terahertz polarizer with performance better than commercial polarizers based on metallic grids.

Nanotubes can be thousands of times longer than they are wide, and the ability to grow them (or cut them) to specific lengths or to dope semiconducting nanotubes to add free carriers would make the tubes highly tunable for terahertz frequencies, Kono said.

"This paper only clarifies the origin of this effect," he said. "Now that we understand it, there's so much to do. We will be making various terahertz devices, architectures and systems based on carbon nanotube plasmons."

Rice alumni Erik Hároz, now a postdoctoral researcher at Los Alamos National Laboratory, and Lei Ren, a researcher at TGS, co-authored the paper with undergraduate student Zehua Jin, postdoctoral researcher Xuan Wang, senior research scientist Rolf Arvidson and Andreas Lüttge, a research professor of Earth science and chemistry, all of Rice. Kono is a professor of electrical and computer engineering and of physics and astronomy and of materials science and nanoengineering.

The Department of Energy, the National Science Foundation and the Robert A. Welch Foundation supported the research.

####

About Rice University
Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,708 undergraduates and 2,374 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice has been ranked No. 1 for best quality of life multiple times by the Princeton Review and No. 2 for "best value" among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to tinyurl.com/AboutRiceU.

Follow Rice News and Media Relations via Twitter @RiceUNews

For more information, please click here

Contacts:
David Ruth
713-348-6327


Mike Williams
713-348-6728

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 Links

Kono Laboratory:

Read the abstract at:

Related News Press

News and information

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

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

Strange but true: turning a material upside down can sometimes make it softer October 20th, 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

Physics

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

The secret to improving liquid crystal's mechanical performance: Better lubricating properties of lamellar liquid crystals could stem from changing the mobility of their structural dislocations by adding nanoparticles October 13th, 2017

What can be discovered at the junction of physics and chemistry October 6th, 2017

Energy against the current on a quantum scale, without contradicting the laws of physics: A piece of research in which the UPV/EHU-University of the Basque Country has participated confirms that merely observing a flow of energy or particles can change its direction October 6th, 2017

Wireless/telecommunications/RF/Antennas/Microwaves

Rice U. study: Vibrating nanoparticles interact: Placing nanodisks in groups can change their vibrational frequencies October 16th, 2017

Govt.-Legislation/Regulation/Funding/Policy

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

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

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

Spinning strands hint at folding dynamics: Rice University lab uses magnetic beads to model microscopic proteins, polymers 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

Discoveries

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

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

Strange but true: turning a material upside down can sometimes make it softer October 20th, 2017

MIPT scientists revisit optical constants of ultrathin gold films October 20th, 2017

Announcements

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

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

Strange but true: turning a material upside down can sometimes make it softer October 20th, 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

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

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

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

Strange but true: turning a material upside down can sometimes make it softer October 20th, 2017

MIPT scientists revisit optical constants of ultrathin gold films 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