Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Short wavelength plasmons observed in nanotubes

29.07.2015

Berkeley Lab researchers create Ludinger liquid plasmons in metallic SWNTs

The term "plasmons" might sound like something from the soon-to-be-released new Star Wars movie, but the effects of plasmons have been known about for centuries. Plasmons are collective oscillations of conduction electrons (those loosely attached to molecules and atoms) that roll across the surfaces of metals while interacting with photons.


This s-SNOM infrared image shows Luttinger-liquid plasmons in a metallic single-walled nanotube.

Courtesy of Feng Wang, Berkeley Lab

For example, plasmons from nanoparticles of gold, silver and other metals interact with visible light photons to generate the vibrant colors displayed by stained glass, a technology that dates back more than 1,000 years. But plasmons have high-technology applications as well. In fact, there's even an emerging technology named for them - plasmonics - that holds great promise for superfast computers and optical microscopy.

At the heart of the high-technology applications of plasmons is their unique ability to confine the energy of a photon into a spatial dimension smaller than the photon's wavelength. Now, a team of researchers with Berkeley Lab's Materials Sciences Division, working at the Advanced Light Source (ALS), has generated and detected plasmons that boast one of the strongest confinement factors ever: the plasmon wavelength is only one hundredth of the free-space photon wavelength.

By focusing infrared light onto the tip of an Atomic Force Microscope, the researchers were able to observe what are called "Luttinger-liquid" plasmons in metallic single-walled nanotubes. A Luttinger-liquid is the theory that describes the flow of electrons through one-dimensional objects, such as a single-walled nanotube (SWNT), much as the Fermi-liquid theory describes the flow of electrons through most two- and three-dimensional metals.

"It is amazing that a plasmon in an individual nanotube, a 1-D object barely a single nanometer in diameter, can even be observed at all," says Feng Wang, a condensed matter physicist with Berkeley Lab's Materials Sciences Division who led this work. "Our use of scattering-type scanning near-field optical microscopy (s-SNOM) is enabling us to study Luttinger-liquid physics and explore novel plasmonic devices with extraordinary sub-wavelength confinement, almost 100 million times smaller in volume than that of free-space photons. What we're observing could hold great promise for novel plasmonic and nanophotonic devices over a broad frequency range, including telecom wavelengths."

Wang, who also holds appointments with the University California (UC) Berkeley Physics Department and the Kavli Energy NanoScience Institute (Kavli-ENSI), is the corresponding author of a paper in Nature Photonics that describes this research. The paper is titled "Observation of a Luttinger-liquid plasmon in metallic single-walled carbon nanotubes." The co-lead authors are Zhiwen Shi and Xiaoping Hong, both members of Wang's UC Berkeley research group. Other co-authors are Hans Bechtel, Bo Zeng, Michael Martin, Kenji Watanabe, Takashi Taniguchi and Yuen-Ron Shen.

Despite the enormous potential of plasmons for the integration of nanoscale photonics and electronics, the development of nanophotonic circuits based on classical plasmons has been significantly hampered by the difficulty in achieving broadband plasmonic waveguides that simultaneously exhibit strong spatial confinement, a high quality factor and low dispersion. The observations of Wang and his colleagues demonstrate that Luttinger-liquid plasmon of 1-D conduction electrons in SWNTs behaves much differently from classical plasmons.

"Luttinger-liquid plasmons in SWNTs propagate at semi-quantized velocities that are independent of carrier concentration or excitation wavelength, and simultaneously exhibit extraordinary spatial confinement, a high quality factor and low dispersion," says co-lead author Shi. "Usually, to be manipulated efficiently with a photonic device, the light wavelength is required to be smaller than the device. By concentrating photon energy at deep sub-wavelength scales, Luttinger-liquid plasmons in SWNTs effectively reduce the light wavelength. This should allow for the miniaturization of photonic devices down to the nanometer scale."

Wang, Shi, Hong and their colleagues observed Luttinger-liquid plasmons using the s-SNOM setup at ALS Beamline 5.4.1. Metallic SWNTs with diameters ranging from 1.2 to 1.7 nanometers were grown, purified and then deposited on a boron nitride substrate. Single wavelength infrared light was focused onto the tip of an Atomic Force Microscope to excite and detect a plasmon wave along an SWNT.

"Our direct observation of Luttinger-liquid plasmons opens up exciting new opportunities," Wang says. "For example, we're now exploring these plasmons in telecom wavelengths, the most widely used in photonics and integrated optics. We're also learning how the properties of these plasmons might be manipulated through electrostatic gating, mechanical strain and external magnetic fields."

###

This research was primarily supported by the U.S. Department of Energy's Office of Science.

Lawrence Berkeley National Laboratory addresses the world's most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab's scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy's Office of Science. For more, visit http://www.lbl.gov.

DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit the Office of Science website at science.energy.gov/.

Media Contact

Lynn Yarris
lcyarris@lbl.gov
510-486-5375

 @BerkeleyLab

http://www.lbl.gov 

Lynn Yarris | EurekAlert!

More articles from Physics and Astronomy:

nachricht Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics

nachricht What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>