Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Rice lab clocks ‘hot’ electrons: Researchers time plasmon-generated electrons moving from nanorods to graphene

Rice University researchers determined the amount of time it takes electrons generated by plasmons in a gold nanorod to transfer to a sheet of graphene through spectroscopic analysis of hundreds of particles. The research will help scientists strategize on ways to gather and store electrons from plasmonic particles.Credit: Anneli Hoggard/Rice University
Rice University researchers determined the amount of time it takes electrons generated by plasmons in a gold nanorod to transfer to a sheet of graphene through spectroscopic analysis of hundreds of particles. The research will help scientists strategize on ways to gather and store electrons from plasmonic particles.

Credit: Anneli Hoggard/Rice University

Abstract:
Plasmonic nanoparticles developed at Rice University are becoming known for their ability to turn light into heat, but how to use them to generate electricity is not nearly as well understood.

Rice lab clocks ‘hot’ electrons: Researchers time plasmon-generated electrons moving from nanorods to graphene

Houston, TX | Posted on January 30th, 2014

Scientists at Rice are working on that, too. They suggest that the extraction of electrons generated by surface plasmons in metal nanoparticles may be optimized.

Rice researchers led by chemist Stephan Link and graduate student Anneli Hoggard are endeavoring to understand the physics; they started by measuring the speed and efficiency of excited "hot" electrons drawn from gold nanoparticles into a sheet of graphene.

It's a good thing for scientists and engineers to know as they work on technologies beyond standard photovoltaic devices that gobble light to drive chemical reactions or next-generation electronics. The work was reported recently in the American Chemical Society journal ACS Nano.

"We've looked at this process on a single-particle level," said lead author Hoggard. "Instead of looking at a device that has many junctions, we've looked at one particle at a time. We had to measure a lot of particles to get good statistics."

Dark-field scattering and photoluminescence spectroscopy of more than 200 nanoparticles helped them determine that it takes about 160 femtoseconds (quadrillionths of a second) for an electron to transfer from the particle to highly conducting graphene, the single-atom-thick form of carbon.

Plasmons are the collective excitation of free electrons in metals that, when stimulated by an energy source like sunlight or a laser, set up a harmonic oscillation of the surface charges similar to waves. In the process, they scatter light that can be read by a spectrometer, which captures and categorizes light according to its wavelengths.

If the energy input is intense enough, the output can be intense as well. In one practical example demonstrated at Rice, plasmon excitation in gold nanoparticles produces heat that instantly turns even ice-cold water into steam.

That excitation energy can also be channeled in other directions through the creation of hot electrons that can transfer to suitable acceptors, Link said, but how fast usable electrons flow from plasmonic nanoparticles is little understood. "The plasmon generates hot electrons that decay very quickly, so intercepting them is a challenge," he said. "We're now realizing these electrons can be useful."

That thought prompted Link's lab to embark upon the painstaking effort to analyze single nanoparticles. The researchers placed gold nanorods on beds of both inert quartz and highly conductive graphene and used a spectrometer to view the line width of the plasmon-scattering spectrum.

The homogeneous line width obtained via single-particle spectroscopy is a measure of the range of wavelengths that resonantly excite a surface plasmon. It's also a measure of the plasmon lifetime. Broad line widths correspond to short lifetimes and narrow line widths to long lifetimes.

The Rice researchers found graphene broadened the nanorods' surface plasmon response - and shortened its lifetime - by accepting hot electrons. By acting as an electron acceptor, the graphene accelerated damping of the plasmons. The difference in damping between the quartz and graphene samples provided a means to calculate the electrons' transfer time.

"The plasmon resonance is determined by the size and the shape of the nanoparticle," Hoggard said. "And it usually appears as a single peak for gold nanorods. But there are important parameters about the peak: The position and the width of the peak can give us information about the particle itself, or the type of environment it's in. So we looked at how the width of the peak changes when nanoparticles are introduced into an electron-accepting environment, which in this case is graphene."

The Rice lab hopes to optimize the connection between the nanoparticles and graphene or another substrate, preferentially a semiconductor that will allow them to trap hot electrons.

"But this experiment wasn't about making a specific device," Link said. "It was about measuring the transfer step. Of course, now we're thinking about designing systems to separate the charge longer, as the electrons transferred quickly back to the gold nanorods. We want to put these hot electrons to work for devices like photodetectors or as catalysts where these electrons can do chemistry.

"It would be fascinating if we could use this process as a source of hot electrons for catalysis and also as an analytical tool for observing such plasmon-enabled reactions. That's the big picture."

The paper's co-authors are Rice graduate students Lin-Yung Wang, Lulu Ma and Jana Olson; former postdoctoral researchers Ying Fang and Zheng Liu; senior Ge You; research scientist Wei-Shun Chang and Pulickel Ajayan, the Benjamin M. and Mary Greenwood Anderson Professor in Mechanical Engineering and Materials Science and of chemistry and chair of Rice's Department of Materials Science and NanoEngineering. Link is an associate professor of chemistry and of electrical and computer engineering.

The Robert A. Welch Foundation, the National Science Foundation, the Army Research Office and the American Chemical Society Petroleum Research Fund supported the research.

####

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

Copyright © Rice University

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 at:

Link Research Group:

Ajayan Research Group:

Related News Press

News and information

Yale researchers’ technology turns wasted heat into power June 27th, 2016

FEI Launches Helios G4 DualBeam Series for Materials Science: The Helios G4 DualBeam Series features new capabilities to enable scientists and engineers to answer the most demanding and challenging scientific questions June 27th, 2016

Russian physicists create a high-precision 'quantum ruler': Physicists have devised a method for creating a special quantum entangled state June 25th, 2016

Nanoscientists develop the 'ultimate discovery tool': Rapid discovery power is similar to what gene chips offer biology June 25th, 2016

Graphene/ Graphite

GraphExeter illuminates bright new future for flexible lighting devices June 23rd, 2016

A new form of hybrid photodetectors with quantum dots and graphene June 19th, 2016

Drum beats from a one atom thick graphite membrane June 15th, 2016

Discovery of gold nanocluster 'double' hints at other shape changing particles: New analysis approach brings two unique atomic structures into focus June 15th, 2016

Govt.-Legislation/Regulation/Funding/Policy

Nanoscientists develop the 'ultimate discovery tool': Rapid discovery power is similar to what gene chips offer biology June 25th, 2016

Ultrathin, flat lens resolves chirality and color: Multifunctional lens could replace bulky, expensive machines June 25th, 2016

Particle zoo in a quantum computer: First experimental quantum simulation of particle physics phenomena June 23rd, 2016

Titan shines light on high-temperature superconductor pathway: Simulation demonstrates how superconductivity arises in cuprates' pseudogap phase June 22nd, 2016

Discoveries

Yale researchers’ technology turns wasted heat into power June 27th, 2016

Superheroes are real: Ultrasensitive nonlinear metamaterials for data transfer June 25th, 2016

Russian physicists create a high-precision 'quantum ruler': Physicists have devised a method for creating a special quantum entangled state June 25th, 2016

Nanoscientists develop the 'ultimate discovery tool': Rapid discovery power is similar to what gene chips offer biology June 25th, 2016

Announcements

Yale researchers’ technology turns wasted heat into power June 27th, 2016

FEI Launches Helios G4 DualBeam Series for Materials Science: The Helios G4 DualBeam Series features new capabilities to enable scientists and engineers to answer the most demanding and challenging scientific questions June 27th, 2016

Russian physicists create a high-precision 'quantum ruler': Physicists have devised a method for creating a special quantum entangled state June 25th, 2016

Nanoscientists develop the 'ultimate discovery tool': Rapid discovery power is similar to what gene chips offer biology June 25th, 2016

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

Yale researchers’ technology turns wasted heat into power June 27th, 2016

Superheroes are real: Ultrasensitive nonlinear metamaterials for data transfer June 25th, 2016

Russian physicists create a high-precision 'quantum ruler': Physicists have devised a method for creating a special quantum entangled state June 25th, 2016

Nanoscientists develop the 'ultimate discovery tool': Rapid discovery power is similar to what gene chips offer biology June 25th, 2016

Energy

Yale researchers’ technology turns wasted heat into power June 27th, 2016

Nanoscientists develop the 'ultimate discovery tool': Rapid discovery power is similar to what gene chips offer biology June 25th, 2016

Researchers discover new chemical sensing technique: Technique allows sharper detail -- and more information -- with near infrared light June 24th, 2016

FEI and University of Liverpool Announce QEMSCAN Research Initiative: University of Liverpool will utilize FEI’s QEMSCAN technology to gain a better insight into oil and gas reserves & potentially change the approach to evaluating them June 22nd, 2016

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







Car Brands
Buy website traffic