Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Artificial Molecules That Switch “Handedness” at Light-Speed: Researchers develop optically switchable chiral THz metamolecules

Abstract:
A multi-institutional team of researchers including scientists with Los Alamos National Laboratory (of the U.S. Department of Energy's National Nuclear Security Administration) has created the first artificial molecules whose chirality can be rapidly switched from a right-handed to a left-handed orientation with a beam of light on them. Switchable molecules hold potentially huge possibilities for the application of terahertz technologies across a wide range of fields, including biomedical research, homeland security and ultrahigh-speed communications.

Artificial Molecules That Switch “Handedness” at Light-Speed: Researchers develop optically switchable chiral THz metamolecules

Los Alamos, NM | Posted on July 11th, 2012

Chirality is the distinct left/right orientation or "handedness" of some types of molecules, meaning the molecule can take one of two mirror image forms. The right-handed and left-handed forms of such molecules, called "enantiomers," can exhibit strikingly different properties. For example, one enantiomer of the chiral molecule limonene smells of lemon, the other smells of orange. The ability to observe or even switch the chirality of molecules using terahertz (trillion-cycles-per-second) electromagnetic radiation is a much-coveted asset in the world of high technology.

"Natural materials can be induced to change their chirality but the process, which involves structural changes to the material, is weak and slow. With our artificial molecules, we've demonstrated strong dynamic chirality switching at light-speed," says Xiang Zhang, one of the leaders of this research and a principal investigator with Berkeley Lab's Materials Sciences Division.

Antoinette Taylor of Los Alamos and her co-authors say that the general design principle of their optically switchable chiral THz metamolecules is not limited to handedness switching but could also be applied to the dynamic reversing of other electromagnetic properties.

Working with terahertz (THz) metamaterials engineered from nanometer-sized gold strips with air as the dielectric, the team fashioned a delicate artificial chiral molecule that they then incorporated with a photoactive silicon medium. Through photoexcitation of their metamolecules with an external beam of light, the researchers observed handedness flipping in the form of circularly polarized emitted THz light. Furthermore, the photoexcitation enabled this chirality flipping and the circular polarization of THz light to be dynamically controlled.

"In contrast to previous demonstrations where chirality was merely switched on or off in metamaterials using photoelectric stimulation, we used an optical switch to actually reverse the chirality of our THz metamolecules," Zhang says.

The paper, in the online Nature Communications, is titled "Photoinduced handedness switching in terahertz chiral metamolecules." (http://dx.doi.org/10.1038/ncomms1908) The other corresponding authors are Shuang Zhang of the University of Birmingham in the United Kingdom, and Antoinette Taylor of DOE's Los Alamos National Laboratory.

The optically switchable chiral THz metamolecules consisted of a pair of 3D meta-atoms of opposite chirality made from precisely structured gold strips. Each meta-atom serves as a resonator with a coupling between electric and magnetic responses that produces strong chirality and large circular dichroism at the resonance frequency.

"When two chiral meta-atoms of the same shape but opposite chirality are assembled to form a metamolecule, the mirror symmetry is preserved, resulting in the vanishing of optical activity," Zhang says. "From a different point of view, the optical activity arising from these two meta-atoms of opposite chirality cancels out each other."

Silicon pads were introduced to each chiral meta-atom in the metamolecule but at different locations. In one meta-atom, the silicon pad bridged two gold strips, and in the other meta-atom, the silicon pad replaced part of a gold strip. The silicon pads broke the mirror symmetry and induced chirality for the combined metamolecule. The pads also functioned as the optoelectronic switches that flipped the chirality of the metamolecule under photoexcitation.

Says corresponding author Shuang Zhang, "Our scheme relies on the combination of two meta-atoms with opposite properties, in which one is functional while the other is inactive within the frequency range of interest. With suitable design, the two meta-atoms respond oppositely to an external stimulus, that is, the inactive one becomes functional and vice versa."

THz electromagnetic radiation - also known as T-rays - falls within the frequency range of molecular vibrations, making it an ideal none-invasive tool for analyzing the chemical constituents of organic and non-organic materials. Being able to flip the handedness of chiral metamolecules and control the circular polarization of THz light could be used to detect toxic and explosive chemicals, or for wireless communication and high-speed data processing systems.

Most biological molecules are chiral, including DNA, RNA and proteins, so THz-based polarimetric devices should also benefit medical researchers and developers of pharmaceutical drugs among others.

"The switchable chirality we can engineer into our metamaterials provides a viable approach towards creating high performance polarimetric devices that are largely not available at terahertz frequencies," says corresponding author Antoinette Taylor. "This frequency range is particularly interesting because it uniquely reveals information about physical phenomena such as the interactions between or within biologically relevant molecules. It may enable control of electronic states in novel material systems, such as cyclotron resonances in graphene and topological insulators."

In addition to the corresponding authors, other authors of the Nature Communications paper were Jiangfeng Zhou, Yong-Shik Park, Junsuk Rho, Ranjan Singh, Sunghyun Nam, Abul Azad, Hou-Tong Chen and Xiaobo Yin.

This research was primarily supported by the DOE Office of Science.

####

About Los Alamos National Laboratory
Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Los Alamos National Security, LLC, a team composed of Bechtel National, the University of California, The Babcock & Wilcox Company, and URS for the Department of Energy’s National Nuclear Security Administration.

Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.

For more information, please click here

Contacts:
Nancy Ambrosiano
505.667.0471


LBL CONTACT:
Lynn Yarris
510.486.5375

Copyright © Los Alamos 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

NanoScience: Giants of the Infinitesimal July 31st, 2014

University of Manchester selects Anasys AFM-IR for coatings and corrosion research July 30th, 2014

Nature inspires a greener way to make colorful plastics July 30th, 2014

Analytical solutions from Malvern Instruments support University of Wisconsin-Milwaukee researchers in understanding environmental effects of nanomaterials July 30th, 2014

Laboratories

Stanford team achieves 'holy grail' of battery design: A stable lithium anode - Engineers use carbon nanospheres to protect lithium from the reactive and expansive problems that have restricted its use as an anode July 27th, 2014

NIST shows ultrasonically propelled nanorods spin dizzyingly fast July 22nd, 2014

Sono-Tek Corporation Announces New Clean Room Rated Laboratory Facility in China July 18th, 2014

Fundamental Chemistry Findings Could Help Extend Moore’s Law: A Berkeley Lab-Intel collaboration outlines the chemistry of photoresist, enabling smaller features for future generations of microprocessors July 15th, 2014

Govt.-Legislation/Regulation/Funding/Policy

New imaging agent provides better picture of the gut July 30th, 2014

Watching Schrödinger's cat die (or come to life): Steering quantum evolution & using probes to conduct continuous error correction in quantum computers July 30th, 2014

Nature inspires a greener way to make colorful plastics July 30th, 2014

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

Nanomedicine

New imaging agent provides better picture of the gut July 30th, 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

FEI adds Phase Plate Technology and Titan Halo TEM to its Structural Biology Product Portfolio: New solutions provide the high-quality imaging and contrast necessary to analyze the 3D structure of molecules and molecular complexes July 28th, 2014

Discoveries

New imaging agent provides better picture of the gut July 30th, 2014

Watching Schrödinger's cat die (or come to life): Steering quantum evolution & using probes to conduct continuous error correction in quantum computers July 30th, 2014

From Narrow to Broad July 30th, 2014

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

Announcements

NanoScience: Giants of the Infinitesimal July 31st, 2014

Nature inspires a greener way to make colorful plastics July 30th, 2014

Analytical solutions from Malvern Instruments support University of Wisconsin-Milwaukee researchers in understanding environmental effects of nanomaterials July 30th, 2014

FEI Unveils New Solutions for Faster Time-to-Analysis in Metals Research July 30th, 2014

Homeland Security

Watching Schrödinger's cat die (or come to life): Steering quantum evolution & using probes to conduct continuous error correction in quantum computers July 30th, 2014

Production of Toxic Gas Sensor Based on Nanorods July 28th, 2014

Nano-sized Chip "Sniffs Out" Explosives Far Better than Trained Dogs: TAU researcher's groundbreaking sensor detects miniscule concentrations of hazardous materials in the air July 23rd, 2014

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

Research partnerships

New imaging agent provides better picture of the gut July 30th, 2014

Breakthrough laser experiment reveals liquid-like motion of atoms in an ultra-cold cluster: University of Leicester research team unlocks insights into creation of new nano-materials July 25th, 2014

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

A Crystal Wedding in the Nanocosmos July 23rd, 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