Researchers measure light fields in 3-D

June 26, 2017, Graz University of Technology
3D image of plasmon fields on nanparticles. Credit: Haberfehlner - TU Graz

Researchers from TU Graz and the University of Graz present the new method of 3-D-plasmon tomography in Nature Communications.

Light as a carrier of information is indispensable to modern communication technology. The controlled manipulation of light quanta, so-called photons, form the basis for wireless transmission or data transfer in optical glass fibres. Due to the wave-like nature of light and its diffraction limit, however, optical components can only focus light down to the micron scale (10-6 m). Ulrich Hohenester from the Institute of Physics at the University of Graz explains: "To enable photons and nanostructures to interact more efficiently, in the research of plasmonics, we couple light onto a metallic nanoparticle, typically made out of gold or silver." Depending on size, shape, environment and material, resonating clouds of electrons are formed – so-called surface plasmons. Hohenester continues: "This collective electron vibration enables us to focus at the nano scale and so use a variety of applications in sensor technology and photovoltaics."

Imaging plasmon fields

The direct observation of plasmon fields is only possible thanks to Austria's most powerful electron microscope – the ASTEM, Austrian Scanning Transmission Electron Microscope, at the Graz Centre for Electron Microscopy. In the last few years, has developed into an ideal method for measuring plasmon fields. Gerald Kothleitner, head of the Working Group for Analytic Transmission Electron Microscopy at TU Graz's Institute of Electron Microscopy and Nanoanalysis, elaborates: "A high-energy electron beam moves near the sample or penetrates it. Electrons in the vicinity of the sample experience a loss of energy, something we can measure spectroscopically. This results in two- dimensional images of plasmon fields at sub-nanometre resolution. Information about the third dimension along which the electrons move is lost in this method."

Breakthrough in 3-D

In the present work which has been published in the open access journal Nature Communications, the NAWI Graz researchers could show for the first time how the third dimension can be reconstructed completely in the framework of a tomographic imaging process by rotating the sample and processing a series of tilted two-dimensional projections. This method works similarly to the computer tomography used in medicine and appropriately bears the name 3-D-plasmon tomography. Kothleitner and Hohenester on the effects of their successful research: "By using this novel method it is now possible to measure fields in a way that will help better understand applications in the fields of sensor technology, and computer storage or even lead to new ones."

Explore further: Two different collective oscillations of electrons occurring on gold nanoparticles observed for the first time

More information: Anton Hörl et al. Tomographic imaging of the photonic environment of plasmonic nanoparticles, Nature Communications (2017). DOI: 10.1038/s41467-017-00051-3

Related Stories

Some like it hot: Simulating single particle excitations

December 17, 2015

Plasmons, which may be thought of as clouds of electrons that oscillate within a metal nanocluster, could serve as antennae to absorb sunlight more efficiently than semiconductors. Understanding and manipulating them is important ...

Could computers reach light speed?

May 28, 2015

Light waves trapped on a metal's surface travel nearly as fast as light through the air, and new research at Pacific Northwest National Laboratory shows these waves, called surface plasmons, travel far enough to possibly ...

Recommended for you

Engineering cellular function without living cells

March 25, 2019

Genes in living cells are activated – or not – by proteins called transcription factors. The mechanisms by which these proteins activate certain genes and deactivate others play a fundamental role in many biological processes. ...

What ionized the universe?

March 25, 2019

The sparsely distributed hot gas that exists in the space between galaxies, the intergalactic medium, is ionized. The question is, how? Astronomers know that once the early universe expanded and cooled enough, hydrogen (its ...

Catalyst advance removes pollutants at low temperatures

March 25, 2019

Researchers at Washington State University, University of New Mexico, Eindhoven University of Technology, and Pacific Northwest National Laboratory have developed a catalyst that can both withstand high temperatures and convert ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.