Core Technology Springs from Nanoscale Rods
October 10, 2016 | Rice UniversityEstimated reading time: 4 minutes
Rice University scientists have discovered how to subtly change the interior structure of semi-hollow nanorods in a way that alters how they interact with light, and because the changes are reversible, the method could form the basis of a nanoscale switch with enormous potential.
“It’s not 0-1, it’s 1-2-3-4-5-6-7-8-9-10,” said Rice materials scientist Emilie Ringe, lead scientist on the project, which is detailed in the American Chemical Society journal Nano Letters. “You can differentiate between multiple plasmonic states in a single particle. That gives you a kind of analog version of quantum states, but on a larger, more accessible scale.”
Ringe and colleagues used an electron beam to move silver from one location to another inside gold-and-silver nanoparticles, something like a nanoscale Etch A Sketch. The result is a reconfigurable optical switch that may form the basis for a new type of multiple-state computer memory, sensor or catalyst.
At about 200 nanometers long, 500 of the metal rods placed end-to-end would span the width of a human hair. However, they are large in comparison with modern integrated circuits. Their multistate capabilities make them more like reprogrammable bar codes than simple memory bits, she said.
“No one has been able to reversibly change the shape of a single particle with the level of control we have, so we’re really excited about this,” Ringe said.
The Rice researchers found they could reconfigure nanoparticle cores with pinpoint precision. That means memories made of nanorods need not be merely on-off, Ringe said, because a particle can be programmed to emit many distinct plasmonic patterns.
The discovery came about when Ringe and her team, which manages Rice’s advanced electron microscopy lab, were asked by her colleague and co-author Denis Boudreau, a professor at Laval University in Quebec, to characterize hollow nanorods made primarily of gold but containing silver.
“Most nanoshells are leaky,” Ringe said. “They have pinholes. But we realized these nanorods were defect-free and contained pockets of water that were trapped inside when the particles were synthesized. We thought: We have something here.”
“We actually were moving silver in the solution, reconfiguring it,” she said. “Because it’s a closed system, we weren’t losing anything and we weren’t gaining anything. We were just moving it around, and could do so as many times as we wished.”
The researchers were then able to map the plasmon-induced near-field properties without disturbing the internal structure — and that’s when they realized the implications of their discovery.
“We made different shapes inside the nanorods, and because we specialize in plasmonics, we mapped the plasmons and it turned out to have a very nice effect,” Ringe said. “We basically saw different electric-field distributions at different energies for different shapes.” Numerical results provided by collaborators Nicolas Large of the University of Texas at San Antonio and George Schatz of Northwestern University helped explain the origin of the modes and how the presence of a water-filled pocket created a multitude of plasmons, she said.
“Using an electron beam is actually not as technologically irrelevant as you might think,” she said. “Electron beams are very easy to generate. And yes, things need to be in vacuum, but other than that, people have generated electron beams for nearly 100 years. I’m sure 40 years ago people were saying, ‘You’re going to put a laser in a disk reader? That’s crazy!’ But they managed to do it.
“I don’t think it’s unfeasible to miniaturize electron-beam technology. Humans are good at moving electrons and electricity around. We figured that out a long time ago,” Ringe said.
The research should trigger the imaginations of scientists working to create nanoscale machines and processes, she said.
“This is a reconfigurable unit that you can access with light,” she said. “Reading something with light is much faster than reading with electrons, so I think this is going to get attention from people who think about dynamic systems and people who think about how to go beyond current nanotechnology. This really opens up a new field.”
Co-authors of the paper are graduate student Josée Daniel of Laval University; former Rice postdoctoral researcher Large, now an assistant professor of physics at the University of Texas at San Antonio; and Schatz, a professor of chemistry at Northwestern University.
The research was supported by the National Science Foundation, the Quest high performance computing facility at Northwestern University, the Natural Sciences and Engineering Research Council of Canada, the Canadian Foundation for Innovation, the Funds for Research of Quebec – Nature and Technology and the University of Laval.
Suggested Items
Rogers Corporation Reports Q1 2024 Results
04/26/2024 | Rogers CorporationNet sales of $213.4 million increased 4.3% versus the prior quarter resulting from higher sales in the AES and EMS business units. AES net sales increased by 4.1% primarily related to higher aerospace and defense (A&D), wireless infrastructure, industrial and renewable energy sales, partially offset by lower EV/HEV and ADAS sales. EMS net sales increased by 2.8% primarily from higher general industrial, A&D and EV/HEV sales, partially offset by seasonally lower portable electronics sales.
Big Win for Defense Production Act Budget Allocation in FY24 Budget
04/23/2024 | I-Connect007 Editorial TeamOne year ago, President Biden issued a determination that chips and packaging are critical for national security. Since that time, much work has been done to continue the conversation in Washington, elevating the importance of the entire chips value chain, and including printed circuit boards and substrates, without which chips cannot operate.
What’s Next Becomes Now at IPC APEX EXPO 2024
04/22/2024 | IPCFrom revolutionary advancements in artificial intelligence, augmented reality and the latest innovations in capital equipment on the show floor to a heightened learner experience through the 16th Electronic Circuits World Convention (ECWC16) technical conference, IPC APEX EXPO 2024 provided education, professional development and numerous networking opportunities, for 3,723 attendees from 57 countries.
Cicor Shareholders Approve All Proposals
04/19/2024 | Cicor Technologies Ltd.At the Annual General Meeting of Cicor Technologies Ltd. in Zurich, the shareholders approved all proposals.
Intel Brings AI-Platform Innovation to Life at the Olympic Games
04/18/2024 | BUSINESS WIREIntel announced its plans for the Olympic and Paralympic Games Paris 2024. Bringing AI Everywhere, Intel will implement artificial intelligence technology powered by Intel processors on the world’s biggest stage.