Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A novel scheme to enhance local electric fields around metal nanostructures

22.10.2012
Enhanced local electric fields are predominant in nonlinear optical properties, particularly in surface-enhanced Raman scattering (SERS), which is a sensitive technique used for the detection of trace amounts of chemicals.

Analysis of the electric fields around nanostructures indicates that they can provide a basic foundation to obtain greater SERS intensity. Professor ZHANG Zhongyue and his group from the College of Physics and Information Technology at Shaanxi Normal University have proposed a novel scheme to enhance the local electric fields around nanostructures.


This is a schematic presentation for illustration of the superposition of the incident waves in the nanorod-groove system.

Credit: ©Science China Press

The scheme is based on manipulation of the incident wave to allow the superposition of the electric fields of multiple beams of light to work as the excitation source for the electrons in the nanostructures, and larger electric fields are thus excited around the nanostructures. Their work, entitled "Enhancing the electric fields around the nanorods by using metal grooves", was published in SCIENCE CHINA Physics, Mechanics & Astronomy 2012, vol. 55 (10).

SERS is one of the most promising applications of the enhanced optical fields generated by the excitation of local surface plasmons in metal nanostructures. The SERS spectrum reveals the vibration modes of molecules, thus conveying specific information with fingerprint-level accuracy. Also, the sensitivity of SERS is one of the highest among the currently available analytical techniques, potentially leading to single molecule detection. Although the SERS signal from a particular molecule originates from both chemical and electromagnetic contributions, the dominant factor in SERS is a result of the local electromagnetic field enhancement caused by the resonant excitation of localized surface plasmons in metal nanostructures.

Because the surface plasmon resonance depends strongly on the shape of the nanostructures, nanostructures with different topological shapes were prepared to enhance the local electric fields. It was found that nanostructure pairs and nanogalaxies could also achieve stronger electric fields because of the electric field couplings or cascade electric field enhancements in the nanosystems.

Unlike previous methods of building the SERS substrates, ZHANG Zhongyue and his group presented a novel scheme to enhance the electric fields around the nanostructures. By manipulating the incident wave, the superposition of the electric fields of multiple beams of light works as the excitation source. When the phase differences between the multiple beams of light are designed appropriately, the excitation fields for electron oscillations in the nanostructures are much greater than those at normal incidence. The electric fields around these nanostructures are also larger than those at normal incidence. The starting point of this scheme is the enhancement of the excitation field for the electron oscillations in the nanostructures, which does not conflict with previous designs that varied the topological shapes of the nanostructures or combined nanostructures to generate larger electric fields.

Following the previously discussed schemes, ZHANG Zhongyue and his group presented the silver nanorod-groove system for SERS substrates. The grooves are used to manipulate the incident waves. The superposition of the electric fields of multiple beams of light works to excite the electron oscillations in the nanorods. As a result, the electric fields around the nanorods in the nanorod-groove system are much greater than those around individual nanorods and those in the nanorod-film system.

For the nanorod-groove system, even with fabrication defects related to the oblique angle of the groove and the location of the nanorod, numerical calculations also show that larger electric fields can be excited around the nanorods. Although the separation distances between the nanorods affect the electric field distributions, the electric fields are always larger than those around individual nanorods and those around the nanorods in the nanorod-film system. Therefore, the nanorod-groove system provides a good structure to further enhance the local electric fields around the nanorods.

See the article: Zhao Y. N., Qin Y., Cao W., et al. Enhancing the electric fields around the nanorods by using metal grooves. SCI CHINA Phys. Mech. Astron., 2012, 55 (10): 1763-1768

ZHANG Zhongyue | EurekAlert!
Further information:
http://www.snnu.edu.cn

More articles from Physics and Astronomy:

nachricht NASA's James Webb Space Telescope completes final cryogenic testing
21.11.2017 | NASA/Goddard Space Flight Center

nachricht Previous evidence of water on mars now identified as grainflows
21.11.2017 | US Geological Survey

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Previous evidence of water on mars now identified as grainflows

21.11.2017 | Physics and Astronomy

NASA's James Webb Space Telescope completes final cryogenic testing

21.11.2017 | Physics and Astronomy

New catalyst controls activation of a carbon-hydrogen bond

21.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>