Featured Research

from universities, journals, and other organizations

Bimetallic nanoantenna separates colors of light

Date:
September 26, 2011
Source:
Chalmers University of Technology
Summary:
Researchers have built a very simple nanoantenna that directs red and blue colors in opposite directions, even though the antenna is smaller than the wavelength of light. The findings can lead to optical nanosensors being able to detect very low concentrations of gases or biomolecules.

The nanoantenna acts as a router for red and blue light, due to the nanoparticles of gold and silver having different optical properties.
Credit: Timur Shegai

Researchers at Chalmers University of Technology have built a very simple nanoantenna that directs red and blue colours in opposite directions, even though the antenna is smaller than the wavelength of light. The findings -- recently published in the online journal Nature Communications -- can lead to optical nanosensors being able to detect very low concentrations of gases or biomolecules.

A structure that is smaller than the wavelength of visible light (390-770 nanometers) should not really be able to scatter light. But that is exactly what the new nanoantenna does. The trick employed by the Chalmers researchers is to build an antenna with an asymmetric material composition, creating optical phase shifts.

The antenna consists of two nanoparticles about 20 nanometers apart on a glass surface, one of silver and one of gold. Experiments show that the antenna scatters visible light so that red and blue colours are directed in opposite directions.

"The explanation for this exotic phenomenon is optical phase shifts," says Timur Shegai, one of the researchers behind the discovery. "The reason is that nanoparticles of gold and silver have different optical properties, in particular different plasmon resonances. Plasmon resonance means that the free electrons of the nanoparticles oscillate strongly in pace with the frequency of the light, which in turn affects the light propagation even though the antenna is so small."

The method used by the Chalmers researchers to control the light by using asymmetric material composition -- such as silver and gold -- is completely new. It is easy to build this kind of nanoantenna; the researchers have shown that the antennas can be fabricated densely over large areas using cheap colloidal lithography.

The research field of nanoplasmonics is a rapidly growing area, and concerns controlling how visible light behaves at the nanoscale using a variety of metal nanostructures. Scientists now have a whole new parameter -- asymmetric material composition -- to explore in order to control the light.

Nanoplasmonics can be applied in a variety of areas, says Mikael Kδll, professor in the research group at Chalmers.

"One example is optical sensors, where you can use plasmons to build sensors which are so sensitive that they can detect much lower concentrations of toxins or signalling substances than is possible today. This may involve the detection of single molecules in a sample, for example, to diagnose diseases at an early stage, which facilitates quick initiation of treatment."

The results were presented at an international conference on optical nanosensors at Chalmers this week. Chalmers is one of the leading universities in nanoplasmonic biosensors, and 130 scientists from around the world are attending the conference.

The research has received financial support from the Swedish Foundation for Strategic Research, the Swedish Research Council and the Gφran Gustafsson Foundation.


Story Source:

The above story is based on materials provided by Chalmers University of Technology. Note: Materials may be edited for content and length.


Journal Reference:

  1. Timur Shegai, Si Chen, Vladimir D. Miljković, Gόlis Zengin, Peter Johansson, Mikael Kδll. A bimetallic nanoantenna for directional colour routing. Nature Communications, 2011; 2: 481 DOI: 10.1038/ncomms1490

Cite This Page:

Chalmers University of Technology. "Bimetallic nanoantenna separates colors of light." ScienceDaily. ScienceDaily, 26 September 2011. <www.sciencedaily.com/releases/2011/09/110923095107.htm>.
Chalmers University of Technology. (2011, September 26). Bimetallic nanoantenna separates colors of light. ScienceDaily. Retrieved April 16, 2014 from www.sciencedaily.com/releases/2011/09/110923095107.htm
Chalmers University of Technology. "Bimetallic nanoantenna separates colors of light." ScienceDaily. www.sciencedaily.com/releases/2011/09/110923095107.htm (accessed April 16, 2014).

Share This



More Matter & Energy News

Wednesday, April 16, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

German Researchers Crack Samsung's Fingerprint Scanner

German Researchers Crack Samsung's Fingerprint Scanner

Newsy (Apr. 16, 2014) — German researchers have used a fake fingerprint made from glue to bypass the fingerprint security system on Samsung's new Galaxy S5 smartphone. Video provided by Newsy
Powered by NewsLook.com
Porsche CEO Says Supercar Is Not Dead: Cue the Spyder 918

Porsche CEO Says Supercar Is Not Dead: Cue the Spyder 918

TheStreet (Apr. 16, 2014) — The Porsche Spyder 918 proves that, in an automotive world obsessed with fuel efficiency, the supercar is not dead. Porsche North America CEO Detlev von Platen attributes the brand's consistent sales growth -- 21% in 2013 -- with an investment in new technology and expanded performance dynamics. The hybrid Spyder 918 has 887 horsepower and 944 lb-ft of torque, but it can run 18 miles on just an electric charge. The $845,000 vehicle is not a consumer-targeted vehicle but a brand statement. Video provided by TheStreet
Powered by NewsLook.com
Ford Mustang Fetes Its 50th Atop Empire State Building

Ford Mustang Fetes Its 50th Atop Empire State Building

AFP (Apr. 16, 2014) — Ford celebrated the 50th birthday of its beloved Mustang by displaying a new model of the convertible on top of the Empire State Building in New York. Duration: 00:28 Video provided by AFP
Powered by NewsLook.com
New York Auto Show Highlights Latest in Car Tech

New York Auto Show Highlights Latest in Car Tech

AP (Apr. 16, 2014) — With more than 1 million visitors annually, the New York International Auto Show is one of the most important shows for the U.S. auto industry. This year's show featured the latest in high technology, and automotive bling. (April 16) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins