Nanotechnology Now





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Visualizing atomic-scale acoustic waves in nanostructures

Electromagnetic radiation is produced when an acoustic wave (purple) generates electric currents (red) as it propagates past an interface between two piezoelectric materials. The radiation propagates outside of the materials and can be detected to determine the shape of the acoustic wave with nearly atomic scale resolution.
Electromagnetic radiation is produced when an acoustic wave (purple) generates electric currents (red) as it propagates past an interface between two piezoelectric materials. The radiation propagates outside of the materials and can be detected to determine the shape of the acoustic wave with nearly atomic scale resolution.

Abstract:
Acoustic waves play many everyday roles - from communication between people to ultrasound imaging. Now the highest frequency acoustic waves in materials, with nearly atomic-scale wavelengths, promise to be useful probes of nanostructures such as LED lights.

Visualizing atomic-scale acoustic waves in nanostructures

LIVERMORE, CA | Posted on July 3rd, 2008

Enter Lawrence Livermore National Laboratory scientists, who discovered a new physical phenomenon that enables them to see high frequency waves by combining molecular dynamics simulations of shock waves with an experimental diagnostic, terahertz (THz) radiation. (The hertz is the base unit of frequency. One hertz simply means one cycle per second. A terahertz is 10^12 hertz.).

The Livermore scientists performed computer simulations of the highest frequency acoustic waves forming spontaneously at the front of shock waves or generated by sub-picosecond pulse-length lasers.

They discovered that, under some circumstances, when such a wave crosses an interface between two materials, tiny electric currents are generated at the interface. These currents produce electromagnetic radiation of THz frequencies that can be detected a few millimeters away from the interface. Part of the wave is effectively converted to electromagnetic radiation, which propagates out of the material where it can be measured.

Most molecular dynamics simulations of shock waves connect to experiments through electronic properties, such as optical reflectivity.

"But this new approach connects to the much lower frequency THz radiation produced by the individual atoms moving around in the shock wave," said Evan Reed, lead author of a paper that appears in the July 7 edition of the journal, Physical Review Letters. "This kind of diagnostic promises to provide new information about shocked materials like the dynamics of crystals pushed to ultra-high strain rates."

Using molecular dynamics simulations, the team, made up of Livermore's Reed and Michael Armstrong in collaboration with Los Alamos National Laboratory colleagues shows that the time-history of the wave can be determined with potentially sub-picosecond, nearly atomic time and space resolution by measuring the electromagnetic field.

Reed and colleagues studied the effect for an interface between two thin films, which are used in LED (light-emitting diode) nanostructures, and are piezoelectric (electric currents that are generated when they are squeezed). Piezoelectric materials have been used for decades as arrival time gauges for shock-wave experiments but have been limited by electrical equipment that can only detect acoustic frequencies less than 10 gigathertz (GHz), precluding observation of the highest frequency acoustic waves. The new THz radiation technique can help improve the time resolution of such approaches.

The technique has other applications as well. It can be applied to determine the structure of many kinds of electronic devices that are constructed using thin film layered structures, such as field-effect transistors.

"The detection of high frequency acoustic waves also has been proposed for use in imaging of quantum dot nanostructures used in myriad optical devices, possibly including solar cells in the future," Reed said. "The technology is not there yet for that application, but our work represents a step closer."

####

About Lawrence Livermore National Laboratory
Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory, with a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by Lawrence Livermore National Security, LLC for the U.S. Department of Energy's National Nuclear Security Administration.

For more information, please click here

Contacts:
Anne M. Stark
Phone: (925) 422-9799

Copyright © Lawrence Livermore National Laboratory

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

News and information

New technique speeds nanoMRI imaging: Multiplexing technique for nanoscale magnetic resonance imaging developed by researchers in Switzerland cuts normal scan time from two weeks to two days May 28th, 2015

Squeezed quantum cats May 28th, 2015

New chip makes testing for antibiotic-resistant bacteria faster, easier: Researchers at the University of Toronto design diagnostic chip to reduce testing time from days to one hour, allowing doctors to pick the right antibiotic the first time May 28th, 2015

Collaboration could lead to biodegradable computer chips May 28th, 2015

Thin films

New technique speeds nanoMRI imaging: Multiplexing technique for nanoscale magnetic resonance imaging developed by researchers in Switzerland cuts normal scan time from two weeks to two days May 28th, 2015

Sandia researchers first to measure thermoelectric behavior by 'Tinkertoy' materials May 20th, 2015

Defects can 'Hulk-up' materials: Berkeley lab study shows properly managed damage can boost material thermoelectric performances May 20th, 2015

Efficiency record for black silicon solar cells jumps to 22.1 percent: Aalto University's researchers improved their previous record by over 3 absolute percents in cooperation with Universitat Politècnica de Catalunya May 18th, 2015

Display technology/LEDs/SS Lighting/OLEDs

Statement by QD Vision regarding European Parliament’s Vote on Cadmium-Based Quantum Dots May 20th, 2015

Possible Futures

Global Nano-Enabled Packaging Market For Food and Beverages Will Reach $15.0 billion in 2020 May 26th, 2015

Simulations predict flat liquid May 21st, 2015

Nature inspires first artificial molecular pump: Simple design mimics pumping mechanism of life-sustaining proteins found in living cells May 19th, 2015

NNCO and Museum of Science Fiction to Collaborate on Nanotechnology and 3D Printing Panels at Awesome Con May 19th, 2015

Announcements

New technique speeds nanoMRI imaging: Multiplexing technique for nanoscale magnetic resonance imaging developed by researchers in Switzerland cuts normal scan time from two weeks to two days May 28th, 2015

Squeezed quantum cats May 28th, 2015

New chip makes testing for antibiotic-resistant bacteria faster, easier: Researchers at the University of Toronto design diagnostic chip to reduce testing time from days to one hour, allowing doctors to pick the right antibiotic the first time May 28th, 2015

Collaboration could lead to biodegradable computer chips May 28th, 2015

Quantum Dots/Rods

Statement by QD Vision regarding European Parliament’s Vote on Cadmium-Based Quantum Dots May 20th, 2015

Toward 'green' paper-thin, flexible electronics May 20th, 2015

Electricity generating nano-wizards: Quantum dots are an ideal nanolab to study the means to turning heat into electricity May 18th, 2015

QD Vision to Showcase Quantum Dot “Firsts” at Display Week 2015: Executives will present, demo current and future quantum dot technology May 13th, 2015

Solar/Photovoltaic

Fine-tuned molecular orientation is key to more efficient solar cells May 26th, 2015

Efficiency record for black silicon solar cells jumps to 22.1 percent: Aalto University's researchers improved their previous record by over 3 absolute percents in cooperation with Universitat Politècnica de Catalunya May 18th, 2015

Wearables may get boost from boron-infused graphene: Rice U. researchers flex muscle of laser-written microsupercapacitors May 18th, 2015

Random nanowire configurations increase conductivity over heavily ordered configurations May 16th, 2015

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