Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > When aluminum outshines gold: Two Rice University studies detail aluminum’s valuable plasmonic properties

When an electromagnetic wave (left) hits a nanomatryushka (center and right) – a solid core inside a hollow shell – the size of the gap determines the strength of the plasmonic response. If the gap is sufficiently small, quantum tunneling through the gap allows plasmons to resonate as though the core and shell are a single particle, dramatically changing their response.Credit: Vikram Kulkarni/Rice University
When an electromagnetic wave (left) hits a nanomatryushka (center and right) – a solid core inside a hollow shell – the size of the gap determines the strength of the plasmonic response. If the gap is sufficiently small, quantum tunneling through the gap allows plasmons to resonate as though the core and shell are a single particle, dramatically changing their response.

Credit: Vikram Kulkarni/Rice University

Abstract:
Humble aluminum's plasmonic properties may make it far more valuable than gold and silver for certain applications, according to new research by Rice University scientists.

When aluminum outshines gold: Two Rice University studies detail aluminum’s valuable plasmonic properties

Houston, TX | Posted on December 2nd, 2013

Because aluminum, as nanoparticles or nanostructures, displays optical resonances across a much broader region of the spectrum than either gold or silver, it may be a good candidate for harvesting solar energy and for other large-area optical devices and materials that would be too expensive to produce with noble or coinage metals.

Until recently, aluminum had not yet been seen as useful for plasmonic applications for several reasons: It naturally oxidizes, and some studies have shown dramatic discrepancies between the resonant "color" of fabricated nanostructured aluminum and theoretical predictions.

The combined work of two Rice labs has addressed each of those hurdles in a pair of new publications.

One paper by the labs of Rice scientists Naomi Halas and Peter Nordlander, "Aluminum for Plasmonics," demonstrates that the color of aluminum nanoparticles depends not only on their size and shape, but also critically on their oxide content. They have shown that, in fact, the color of an aluminum nanoparticle provides direct evidence of the amount of oxidation of the aluminum material itself. The paper appears in the American Chemical Society (ACS) journal ACS Nano.

Manufacturing pure aluminum nanoparticles has been a roadblock in their development for plasmonics, but the Halas lab created a range of disk-shaped particles from 70 to 180 nanometers in diameter to test their properties. The researchers found that while gold nanoparticles' plasmons resonate in visible wavelengths from 550 to 700 nanometers and silver from 350 to 700, aluminum can reach into the ultraviolet, to about 200 nanometers.

The labs also characterized the weakening effect of naturally occurring but self-passivating oxidation on aluminum surfaces. "For iron, rust goes right through," Nordlander said. "But for pure aluminum, the oxide is so hard and impermeable that once you form a three-nanometer sheet of oxide, the process stops." To prove it, the researchers left their disks exposed to the open air for three weeks before testing again and found their response unchanged.

"The reason we use gold and silver in nanoscience is that they don't oxidize. But finally, with aluminum, nature has given us something we can exploit," Nordlander said.

The second paper by Nordlander and his group predicts quantum effects in plasmonic aluminum that are stronger than those in an analogous gold structure when in the form of a nanomatryushka, multilayer nanoparticles named for the famous Russian nesting dolls. Nordlander discovered the quantum mechanical effects in these materials are strongly connected to the size of the gap between the shell and the core. The paper appeared recently in the ACS journal Nano Letters.

"In addition to being a cheap and tunable material, it exhibits quantum mechanical effects at larger, more accessible and more precise ranges than gold or silver," Nordlander said. "We see this as a foundational paper."

Nordlander used computer simulations to investigate the discrepancies between classical electromagnetics and quantum mechanics, and precisely where the two theories diverge in both gold and aluminum nanomatryushkas. "Aluminum exhibits much more quantum behavior at a given gap size than gold," he said. "Basically for very small gaps, everything is in the quantum realm (where subatomic forces rule), but as you make the gap larger, the system turns to classical physics."

By small, Nordlander means well below a single nanometer (a billionth of a meter). With the gap between core and shell in a gold nanomatryushka at about half a nanometer, he and lead author Vikram Kulkarni, a Rice graduate student, found electrons gained the capability to tunnel from one layer to another in the nanoparticle. A 50 percent larger gap in aluminum allowed for the same quantum effect. In both cases, quantum tunneling through the gap allowed plasmons to resonate as though the core and shell were a single particle, dramatically enhancing their response.

The calculations should be of great interest to those who use nanoparticles as probes in Raman spectroscopy, where quantum tunneling between particles can dampen electric fields and throw off classical calculations, he said.

Nordlander noted that Kulkarni's algorithm allowed the team to run one of the largest quantum plasmonics calculations ever performed. They used the power of Rice's BlueBioU supercomputer to track a massive number of electrons. "It's easy to keep track of two children, but imagine if you had more than a million," he said.

Lead authors of "Aluminum for Plasmonics" are Rice graduate students Mark Knight and Nicholas King. Co-authors include graduate student Lifei Liu and Henry Everitt, a chief scientist at the U.S. Army's Charles Bowden Research Lab, Redstone Arsenal, Ala., and an adjunct professor at Duke University. The research was supported by the Robert A. Welch Foundation, the National Security Science and Engineering Faculty Fellowship, the Air Force Office of Scientific Research, the National Science Foundation's Major Research Instrumentation Program, the Army's in-house laboratory-independent research program and the Army Research Office.

Rice alumnus Emil Prodan, an assistant professor of physics at Yeshiva University, New York, is co-author of "Quantum Plasmonics: Optical Properties of a Nanomatryushka."

The research was supported by the Welch Foundation, the U.S. Army Research Laboratory, the National Institutes of Health, the National Science Foundation and an IBM Shared University Research Award in partnership with Cisco, Qlogic and Adaptive Computing. BlueBioU is administered by Rice's Ken Kennedy Institute for Information Technology.

Halas is the Stanley C. Moore Professor of Electrical and Computer Engineering, a professor of chemistry, biomedical engineering and physics and astronomy and director of the Laboratory for Nanophotonics. Nordlander is a professor of physics and astronomy and in electrical and computer engineering.

####

About Rice University
Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation’s top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,708 undergraduates and 2,374 graduate students, Rice’s undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice has been ranked No. 1 for best quality of life multiple times by the Princeton Review and No. 2 for “best value” among private universities by Kiplinger’s Personal Finance. To read “What they’re saying about Rice,” go to tinyurl.com/AboutRiceU.

Follow Rice News and Media Relations via Twitter @RiceUNews

For more information, please click here

Contacts:
David Ruth
713-348-6327


Mike Williams
713-348-6728

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 Links

Read the abstract for “Aluminum for Plasmonics” at:

Read the abstract for “Quantum Plasmonics: Optical Properties of a Nanomatryushka” at:

Halas Nanophotonics Group:

Nordlander Nanophotonics Group:

Related News Press

News and information

'Stealth' nanoparticles could improve cancer vaccines October 1st, 2014

Stressed Out: Research Sheds New Light on Why Rechargeable Batteries Fail October 1st, 2014

New Absorber Will Lead to Better Biosensor: Biosensors are more sensitive and able to detect smaller changes in the environment October 1st, 2014

Graphene chips are close to significant commercialization October 1st, 2014

Govt.-Legislation/Regulation/Funding/Policy

Novel approach to magnetic measurements atom-by-atom October 1st, 2014

'Stealth' nanoparticles could improve cancer vaccines October 1st, 2014

NREL Announces New Center Directors to lead R&D, Analysis Efforts September 30th, 2014

A Heartbeat Away? Hybrid "Patch" Could Replace Transplants: TAU researcher harnesses gold nanoparticles to engineer novel biocompatible cardiac patch September 30th, 2014

Discoveries

Novel approach to magnetic measurements atom-by-atom October 1st, 2014

Nanoparticles Accumulate Quickly in Wetland Sediment: Aquatic food chains might be harmed by molecules "piggybacking" on carbon nanoparticles October 1st, 2014

'Stealth' nanoparticles could improve cancer vaccines October 1st, 2014

Stressed Out: Research Sheds New Light on Why Rechargeable Batteries Fail October 1st, 2014

Announcements

'Stealth' nanoparticles could improve cancer vaccines October 1st, 2014

Stressed Out: Research Sheds New Light on Why Rechargeable Batteries Fail October 1st, 2014

New Absorber Will Lead to Better Biosensor: Biosensors are more sensitive and able to detect smaller changes in the environment October 1st, 2014

Graphene chips are close to significant commercialization October 1st, 2014

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals

Novel approach to magnetic measurements atom-by-atom October 1st, 2014

'Stealth' nanoparticles could improve cancer vaccines October 1st, 2014

Stressed Out: Research Sheds New Light on Why Rechargeable Batteries Fail October 1st, 2014

New Absorber Will Lead to Better Biosensor: Biosensors are more sensitive and able to detect smaller changes in the environment October 1st, 2014

Military

UT Arlington researchers develop transparent nanoscintillators for radiation detection for medical safety and homeland security September 29th, 2014

'Pixel' engineered electronics have growth potential: Rice, Oak Ridge, Vanderbilt, Penn scientists lead creation of atom-scale semiconducting composites September 29th, 2014

Nanotechnology leads to better, cheaper LEDs for phones and lighting September 24th, 2014

Engineered proteins stick like glue — even in water: New adhesives based on mussel proteins could be useful for naval or medical applications September 22nd, 2014

Energy

New Absorber Will Lead to Better Biosensor: Biosensors are more sensitive and able to detect smaller changes in the environment October 1st, 2014

Production of Filters for Separation of Water from Petroleum Products in Iran October 1st, 2014

Production of Anticorrosive Chromate Nanocoatings in Iran September 27th, 2014

On the Road to Artificial Photosynthesis: Berkeley Lab Study Reveals Key Catalytic Factors in Carbon Dioxide Reduction September 25th, 2014

Photonics/Optics/Lasers

New Absorber Will Lead to Better Biosensor: Biosensors are more sensitive and able to detect smaller changes in the environment October 1st, 2014

Speed at its limits September 30th, 2014

'Pixel' engineered electronics have growth potential: Rice, Oak Ridge, Vanderbilt, Penn scientists lead creation of atom-scale semiconducting composites September 29th, 2014

Southampton scientists grow a new challenger to graphene September 23rd, 2014

Solar/Photovoltaic

New Absorber Will Lead to Better Biosensor: Biosensors are more sensitive and able to detect smaller changes in the environment October 1st, 2014

University of Electro-Communications research: High density quantum dots for powerful solar cells September 25th, 2014

On the Road to Artificial Photosynthesis: Berkeley Lab Study Reveals Key Catalytic Factors in Carbon Dioxide Reduction September 25th, 2014

Solar cell compound probed under pressure September 25th, 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