Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Plasmonics Shines Light on Confining Chemical Reaction

Abstract:
Chemical reactions can be easily squizzed and manipulated into a space with size down to 30nm, smaller than one millionth of table tennis ball. Researchers at Stanford University, California, have recently achieved unprecedented spatial control over growth of semiconductor nanowires and carbon nanotubes taking advantage of novel optical properties of metallic nanoparticles. (published in the most recent issue of Nano Lett.)

Plasmonics Shines Light on Confining Chemical Reaction

Palo Alto, CA | Posted on December 4th, 2007

Metallic nanoparticles, especially noble metals like gold, silver and copper, can support light-induced surface plasmon-polaritons (SPPs), or collective electron oscillations. SPPs are electromagnetic ("light") waves that propagate along metal-dielectric interfaces and are coupled to the free electrons in the metal. When illuminated with an electromagnetic waves matching the surface plasmon, called as surface plasmon resonance (SPR), local electromagentic field at the proximity of metal nanoparticles and absorption of the particles to the light will be dramatically enhanced. Most of the absorbed energy will be subsequently converted to heat through a procedure called as plasmon damping (Landau damping ).

As metal nanostructures are used widely as catalysts in the chemical industry as well, the team, led by Mark L. Brongersma, an assistant professor affiliated with Department of Materials Science and Engineering at Stanford, has envisioned a golden opportunity to couple plasmonics and catalysis seeking a new pathway to control chemical reaction.

To find out, Brongersma and his colleagures put an assemly of gold nanoparticles into a flow of source gas, and illuminated the nanoparticles by a laser with power intensity carefully-controlled. The wavelenght of the laser (532nm) is chosn to be compatible with SPR absorption of the particles. They shown that the growth of silicon and germanium nanowires (NWs) and carbon nanotubes (NTs) can be initiated and confined at nanoscale-sized space and down to single NW or NT level. Neverthess, the growth can be positioned at arbitrarily specififed location moving the laser spot. Surprisingly, the laser power needed to initiate the growth (normally at ~500 degree C) is only at few milliwatt. "The strong, resonantly enhanced absorption by metallic nanostructures enables such efficient local heating that a low power laser pointer provides sufficient power to locally generate hundreds of degrees of temperature change." said Mark L. Brongersma.

As well as performing experiments, Brongersma and his team modelled the photothermal energy-conversion and heat conduction process in detail. The researchers came up with an result that indicates the heat generated by this techinique is highly confined into the illuminated area and the onset of heating or cooling can be finished in a scale of 1 ns (10-10 s ). "That means we are able to grow nanowires or nanotubes directly in devices architecture to make a nanodevices, and would be able to grow those materials in a controlled way monolayer by monlayer ", said Linyou Cao, a graduate student at Stanford and leading author of the paper. Most nanowires and nanotubes are currently grown in a globally heated furnace. Such procedures can damage pre-existing device structures, and hence device fabrication typically requires laborious post-growth processing.

" We anticipate that the versatility and simplicity of the technique will result in its broad adaptation by many researchers and engineers that require a nanoscale heating strategy", told Mark L. Brongersma to nanotechweb.org, " In general, the successful demonstration of high spatial and temporal control over nanoscale thermal environments inspires new pathways for manipulating a range of important thermally-stimulated processes and the development of novel photothermal devices. "

####

For more information, please click here

Contacts:
Linyou Cao
650-799-8272

Copyright © Stanford 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

Chip Technology

A*STAR and industry form S$200M semiconductor R&D July 25th, 2014

A Crystal Wedding in the Nanocosmos July 23rd, 2014

Nanometrics Announces Upcoming Investor Events July 22nd, 2014

Penn Study: Understanding Graphene’s Electrical Properties on an Atomic Level July 22nd, 2014

Nanotubes/Buckyballs

SouthWest NanoTechnologies Names NanoSperse as A SWeNT Certified Compounder July 29th, 2014

A new way to make microstructured surfaces: Method can produce strong, lightweight materials with specific surface properties July 29th, 2014

UCF Nanotech Spinout Developing Revolutionary Battery Technology: Power the Next Generation of Electronics with Carbon July 23rd, 2014

University of Houston researchers create new method to draw molecules from live cells: Technique using magnetic nanomaterials offers promise for diagnosis, gene therapy July 17th, 2014

Discoveries

Tough foam from tiny sheets: Rice University lab uses atom-thick materials to make ultralight foam July 29th, 2014

Zenosense, Inc. July 29th, 2014

Optimum inertial design for self-propulsion: A new study investigates the effects of small but finite inertia on the propulsion of micro and nano-scale swimming machines July 29th, 2014

A new way to make microstructured surfaces: Method can produce strong, lightweight materials with specific surface properties July 29th, 2014

Announcements

Tough foam from tiny sheets: Rice University lab uses atom-thick materials to make ultralight foam July 29th, 2014

Zenosense, Inc. July 29th, 2014

Optimum inertial design for self-propulsion: A new study investigates the effects of small but finite inertia on the propulsion of micro and nano-scale swimming machines July 29th, 2014

A new way to make microstructured surfaces: Method can produce strong, lightweight materials with specific surface properties July 29th, 2014

Photonics/Optics/Lasers

NUS scientists use low cost technique to improve properties and functions of nanomaterials: By 'drawing' micropatterns on nanomaterials using a focused laser beam, scientists could modify properties of nanomaterials for effective applications in photonic and optoelectric applicat July 22nd, 2014

Carbyne morphs when stretched: Rice University calculations show carbon-atom chain would go metal to semiconductor July 21st, 2014

Tiny laser sensor heightens bomb detection sensitivity July 19th, 2014

Future Electronics May Depend on Lasers, Not Quartz July 17th, 2014

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







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE