Nav: Home

Rice lab's bright idea is pure gold

June 29, 2020

HOUSTON - (June 29, 2020) - Seeing light emerge from a nanoscale experiment didn't come as a big surprise to Rice University physicists. But it got their attention when that light was 10,000 times brighter than they expected.

Condensed matter physicist Doug Natelson and his colleagues at Rice and the University of Colorado Boulder discovered this massive emission from a nanoscale gap between two electrodes made of plasmonic materials, particularly gold.

The lab had found a few years ago that excited electrons leaping the gap, a phenomenon known as tunneling, created a larger voltage than if there were no gap in the metallic platforms.

In the new study in the American Chemical Society journal Nano Letters, when these hot electrons were created by electrons driven to tunnel between gold electrodes, their recombination with holes emitted bright light, and the greater the input voltage, the brighter the light.

The study led by Natelson and lead authors Longji Cui and Yunxuan Zhu appears in the American Chemical Society journal Nano Letters and should be of interest to those who research optoelectronics, quantum optics and photocatalysis.

The effect depends upon the metal's plasmons, ripples of energy that flow across its surface. "People have explored the idea that the plasmons are important for the electrically driven light emission spectrum, but not generating these hot carriers in the first place," Natelson said. "Now we know plasmons are playing multiple roles in this process."

The researchers formed several metals into microscopic, bow tie-shaped electrodes with nanogaps, a test bed developed by the lab that lets them perform simultaneous electron transport and optical spectroscopy. Gold was the best performer among electrodes they tried, including compounds with plasmon-damping chromium and palladium chosen to help define the plasmons' part in the phenomenon.

"If the plasmons' only role is to help couple the light out, then the difference between working with gold and something like palladium might be a factor of 20 or 50," Natelson said. "The fact that it's a factor of 10,000 tells you that something different is going on."

The reason appears to be that plasmons decay "almost immediately" into hot electrons and holes, he said. "That continuous churning, using current to kick the material into generating more electrons and holes, gives us this steady-state hot distribution of carriers, and we've been able to maintain it for minutes at a time," Natelson said.

Through the spectrum of the emitted light, the researchers' measurements revealed those hot carriers are really hot, reaching temperatures above 3,000 degrees Fahrenheit while the electrodes stay relatively cool, even with a modest input of about 1 volt.

Natelson said the discovery could be useful in the advance of optoelectronics and quantum optics, the study of light-matter interactions at vanishingly small scales. "And on the chemistry side, this idea that you can have very hot carriers is exciting," he said. "It implies that you may get certain chemical processes to run faster than usual.

"There are a lot of researchers interested in plasmonic photocatalysis, where you shine light in, excite plasmons and the hot carriers from those plasmons do interesting chemistry," he said. "This complements that. In principle, you could electrically excite plasmons and the hot carriers they produce can do interesting chemistry."
-end-
Co-authors of the paper are Rice graduate students Mahdiyeh Abbasi and Burak Gerislioglu, lecturer Arash Ahmadivand and Peter Nordlander, the Wiess Chair in Physics and Astronomy and a professor of electrical and computer engineering, and of materials science and nanoengineering. Cui, a former postdoctoral fellow at Rice, is now an assistant professor of mechanical engineering and materials science and engineering at the University of Colorado Boulder. Zhu is a graduate student at Rice. Natelson is chair and a professor of physics and astronomy and a professor of electrical and computer engineering and of materials science and nanoengineering.

The J. Evans Attwell Welch Fellowship, Rice's Smalley-Curl Institute, the Robert A. Welch Foundation, the University of Colorado, the National Science Foundation and the Air Force Office of Scientific Research supported the research.

Read the abstract at https://pubs.acs.org/doi/10.1021/acs.nanolett.0c02121.

This news release can be found online at https://news.rice.edu/2020/06/29/rice-labs-bright-idea-is-pure-gold/

Follow Rice News and Media Relations via Twitter @RiceUNews.

Related materials:

'Hot' electrons don't mind the gap: http://news.rice.edu/2017/05/08/hot-electrons-dont-mind-the-gap-2/

Single molecules can take the heat: http://news.rice.edu/2019/07/18/single-molecules-can-take-the-heat/

Natelson Research Group: http://natelson.web.rice.edu/group.html

Department of Physics and Astronomy: https://physics.rice.edu

Wiess School of Natural Sciences: https://naturalsciences.rice.edu

Images for download:

https://news-network.rice.edu/news/files/2020/06/0629_ELECTRONS-1-WEB.jpg

Rice University physicists discover that plasmonic metals can be prompted to produce "hot carriers" that in turn emit unexpectedly bright light in nanoscale gaps between electrodes. The phenomenon could be useful for photocatalysis, quantum optics and optoelectronics. (Credit: Illustration by Longji Cui and Yunxuan Zhu/Rice University)

https://news-network.rice.edu/news/files/2020/06/0629_ELECTRON-2-WEB.jpg

At top, an illustration shows the experimental setup developed at Rice University to study the effect of how current prompts localized surface plasmons (LSPs) to produce hot carriers in the nanogap between two electrodes. Center, a photo shows a light-emitting tunnel junction between two gold electrodes with input from 1 to 1.2 volts. At bottom, a spectrographic plot shows the photon energy and intensity produced at the junction. (Credit: Natelson Research Group/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 3,962 undergraduates and 3,027 graduate students, Rice's undergraduate student-to-faculty ratio is just under 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for lots of race/class interaction and No. 4 for quality of life by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance.

Rice University

Related Nanoscale Articles:

House cleaning on the nanoscale
A team of scientists at Friedrich-Alexander Universität Erlangen-Nürnberg (FAU) has developed a novel mechanical cleaning method for surfaces on the nanoscale.
As electronics shrink to nanoscale, will they still be good as gold?
As circuit interconnects shrink to nanoscale, will the pressure caused by thermal expansion when current flows through wires cause gold to behave more like a liquid than a solid -- making nanoelectronics unreliable?
A joint venture at the nanoscale
Scientists at Argonne National Laboratory report fabricating and testing a superconducting nanowire device applicable to high-speed photon counting.
Bending diamond at the nanoscale
A team of Australian scientists has discovered diamond can be bent and deformed, at the nanoscale at least.
Creating a nanoscale on-off switch for heat
Researchers create a polymer thermal regulator that can quickly transform from a conductor to an insulator, and back again.
Magnetic tuning at the nanoscale
Physicists from the German research center Helmholtz-Zentrum Dresden-Rossendorf (HZDR) are working to produce engineered magnetic nanostructures and to tailor material properties at the nanoscale.
Scientists can now control thermal profiles at the nanoscale
Scientists have designed and tested an experimental system that uses a near-infrared laser to actively heat two gold nanorod antennae to different temperatures.
New study shows nanoscale pendulum coupling
In 1665, Lord Christiaan Huygens found that two pendulum clocks, hung in the same wooden structure, oscillated spontaneously and perfectly in line but in opposite directions: the clocks oscillated in anti-phase.
Research reveals liquid gold on the nanoscale
Swansea University researchers have discovered what liquid gold looks like on the nanoscale - and in doing so have mapped the way in which nanoparticles melt, which is relevant to the manufacturing and performance of nanotech devices such as bio-sensors, nanochips , gas sensors, and catalysts.
Nanoscale thermometers from diamond sparkles
The development of a novel, non-invasive technique that uses quantum light to measure temperature at the nanoscale will have immediate applications for both industry and fundamental scientific research, scientists say.
More Nanoscale News and Nanoscale Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Meditations on Loneliness
Original broadcast date: April 24, 2020. We're a social species now living in isolation. But loneliness was a problem well before this era of social distancing. This hour, TED speakers explore how we can live and make peace with loneliness. Guests on the show include author and illustrator Jonny Sun, psychologist Susan Pinker, architect Grace Kim, and writer Suleika Jaouad.
Now Playing: Science for the People

#565 The Great Wide Indoors
We're all spending a bit more time indoors this summer than we probably figured. But did you ever stop to think about why the places we live and work as designed the way they are? And how they could be designed better? We're talking with Emily Anthes about her new book "The Great Indoors: The Surprising Science of how Buildings Shape our Behavior, Health and Happiness".
Now Playing: Radiolab

The Third. A TED Talk.
Jad gives a TED talk about his life as a journalist and how Radiolab has evolved over the years. Here's how TED described it:How do you end a story? Host of Radiolab Jad Abumrad tells how his search for an answer led him home to the mountains of Tennessee, where he met an unexpected teacher: Dolly Parton.Jad Nicholas Abumrad is a Lebanese-American radio host, composer and producer. He is the founder of the syndicated public radio program Radiolab, which is broadcast on over 600 radio stations nationwide and is downloaded more than 120 million times a year as a podcast. He also created More Perfect, a podcast that tells the stories behind the Supreme Court's most famous decisions. And most recently, Dolly Parton's America, a nine-episode podcast exploring the life and times of the iconic country music star. Abumrad has received three Peabody Awards and was named a MacArthur Fellow in 2011.