Featured Research

from universities, journals, and other organizations

Experiments on tiny gold prisms help to explain unusual electrodynamics of nanostructures

Date:
February 13, 2014
Source:
The Agency for Science, Technology and Research (A*STAR)
Summary:
Nanoplasmonics -- the study of light manipulation on the nanometer scale -- has contributed to the production of novel devices for chemical and biological sensing, signal processing and solar energy. However, components at such small scales experience strange effects that classical electrodynamics cannot explain. A particular challenge for theorists lies in isolating so-called 'nonlocal' effects, whereby the optical properties of a particle are not constant but depend on nearby electromagnetic fields.

Nanoplasmonics -- the study of light manipulation on the nanometer scale -- has contributed to the production of novel devices for chemical and biological sensing, signal processing and solar energy. However, components at such small scales experience strange effects that classical electrodynamics cannot explain. A particular challenge for theorists lies in isolating so-called 'nonlocal' effects, whereby the optical properties of a particle are not constant but depend on nearby electromagnetic fields.

Now, Joel Yang and colleagues at the A*STAR Institute of Materials Research and Engineering in Singapore, with co-workers in the United Kingdom and China, have used both simulations and experiments to investigate the nonlocal effects displayed by electrons in metal nanostructures.

The team developed three-dimensional simulations of electron-energy loss spectroscopy (EELS) spectra. EELS is a powerful laboratory technique that can provide information on nanostructure geometries, but also gives rise to nonlocal effects. An EELS device is used to fire energetic electrons at a metal nanostructure and then to measure how much energy the electrons lose when they excite plasmon resonances in the sample. Previously, it had been difficult for experimentalists to correctly interpret EELS spectra because the nonlocal effects are not considered in current theory -- the relevant solutions of Maxwell's field equations.

Yang and co-workers present the first full three-dimensional solution of Maxwell's equations for a sample being probed by an EELS source. "Our theoretical configuration mimics the experimental setup and the equations were, for the first time, implemented and solved using commercial software," says Yang.

The researchers applied their theory to triangular gold nanoprisms and concluded that significant nonlocal effects occur when the side length of the prisms is smaller than 10-50 nanometers, causing a spatial dispersion of electromagnetic fields. They then examined real EELS results for gold 'bowtie' nanostructures -- each gold bowtie was created by joining two nanoprisms at their peaks using gold bridges as narrow as 1.6 nanometers (see image).

The real bowties exhibited a similar spatial field dispersion to that anticipated for single prisms, but with greatly reduced high-frequency conduction at the narrow connective bridges. The researchers speculate that the field reduction is caused by two factors not included in their model -- quantum confinement in the narrow bridges as well as electron scattering from grain boundaries. These factors help to explain the interplay between nonlocality and geometry.

"Existing models tend to treat metals as having homogeneous optical properties," says Yang. "Our results suggest that at the nanoscale we need to take account of quantum confinement and granularity."


Story Source:

The above story is based on materials provided by The Agency for Science, Technology and Research (A*STAR). Note: Materials may be edited for content and length.


Journal Reference:

  1. Aeneas Wiener, Huigao Duan, Michel Bosman, Andrew P. Horsfield, John B. Pendry, Joel K. W. Yang, Stefan A. Maier, Antonio I. Fernαndez-Domνnguez. Electron-Energy Loss Study of Nonlocal Effects in Connected Plasmonic Nanoprisms. ACS Nano, 2013; 7 (7): 6287 DOI: 10.1021/nn402323t

Cite This Page:

The Agency for Science, Technology and Research (A*STAR). "Experiments on tiny gold prisms help to explain unusual electrodynamics of nanostructures." ScienceDaily. ScienceDaily, 13 February 2014. <www.sciencedaily.com/releases/2014/02/140213121614.htm>.
The Agency for Science, Technology and Research (A*STAR). (2014, February 13). Experiments on tiny gold prisms help to explain unusual electrodynamics of nanostructures. ScienceDaily. Retrieved September 21, 2014 from www.sciencedaily.com/releases/2014/02/140213121614.htm
The Agency for Science, Technology and Research (A*STAR). "Experiments on tiny gold prisms help to explain unusual electrodynamics of nanostructures." ScienceDaily. www.sciencedaily.com/releases/2014/02/140213121614.htm (accessed September 21, 2014).

Share This



More Matter & Energy News

Sunday, September 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

What This MIT Sensor Could Mean For The Future Of Robotics

What This MIT Sensor Could Mean For The Future Of Robotics

Newsy (Sep. 20, 2014) — MIT researchers developed a light-based sensor that gives robots 100 times the sensitivity of a human finger, allowing for "unprecedented dexterity." Video provided by Newsy
Powered by NewsLook.com
MIT BioSuit A New Take On Traditional Spacesuits

MIT BioSuit A New Take On Traditional Spacesuits

Newsy (Sep. 19, 2014) — The MIT BioSuit could be an alternative to big, bulky traditional spacesuits, but the concept needs some work. Video provided by Newsy
Powered by NewsLook.com
New Music With Recycled Instruments at Colombia Fest

New Music With Recycled Instruments at Colombia Fest

AFP (Sep. 19, 2014) — Jars, bottles, caps and even a pizza box, recovered from the trash, were the elements used by four musical groups at the "RSFEST2014 Sonorities Recycling Festival", in Colombian city of Cali. Duration: 00:49 Video provided by AFP
Powered by NewsLook.com
Virtual Reality Headsets Unveiled at Tokyo Game Show

Virtual Reality Headsets Unveiled at Tokyo Game Show

AFP (Sep. 18, 2014) — Several companies unveiled virtual reality headsets at the Tokyo Game Show, Asia's largest digital entertainment exhibition. Duration: 00:48 Video provided by AFP
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