Researchers devise a new way to examine the movement of low-energy electrons

June 13, 2017
The optical cavity effects in a bare core particle (upper) and a core particle coated with a shell (upper). Shown are variations in the square of the local light intensity I2, which can be used to spatially control the generation of electrons. Credit: Stavros Amanatidis, Bruce Yoder and Ruth Signorell

The scientific community has known about the existence of electrons for over a hundred years, but there are important facets of their interaction with matter that remain shrouded in mystery. One particular area of interest is low-energy electrons or electrons that have kinetic energy levels of about 10 electronvolts (eV) or less. These electrons affect the functioning of insulators in electronic systems and are responsible for radiation damage in human and other biological tissue.

The classic method for studying how electrons interact with matter is by analyzing their scattering through thin layers of a known substance. This happens by directing a stream of electrons at the layer and analyzing the subsequent deviations in the electrons' trajectories.

"High-energy electrons primarily interact with the individual atoms in a substance and their scattering can be predicted by existing generalized models," said Ruth Signorell, a professor of physical chemistry at ETH Zürich, the Swiss Federal Institute of Technology. "In contrast, low-energy electrons interact with the whole molecular network, which includes the chemical bonds and vibrational motion of the atoms within the substance, and their scattering is currently too complex to predict with a model. With this in mind, we have been developing an alternative approach to measuring the movement of low-energy electrons."

Signorell and her colleagues explain their work this week in The Journal of Chemical Physics.

"One of our key ideas has been the development of a technique we call the ' overlayer method'. It involves generating aerosol droplets that consist of a solid core and a shell made of organic materials that mimic some of the polymers one would find in electronics. Working with these droplets in a vacuum, we can use to induce the core to release electrons that travel through the shell. When they reach the surface and escape, we can measure different metrics such as their intensity," Signorell said.

"The aerosol overlayer method offers two major advantages," Signorell said. "First, it makes it easier to separate the issues of the transport of electrons through the shell versus their formation in the core. Second, droplets with a size comparable to the wavelength of the laser act as resonators for the laser light. This can be exploited to generate a wealth of additional information on the interaction of electrons with matter."

"The major challenge of this method is accurately determining the size of the core and shell of the . While it is still difficult to measure these quantities, the accuracy of the measurements affects the accuracy of the scattering information that is generated," Signorell said.

Going forward, Signorell and her colleagues are interested in broadening the scope of their work with the aerosol overlayer method.

"We want to apply the aerosol overlayer to different materials of varied thicknesses. We are particularly interested in very thin shells and how their structural changes affect the escape of electrons from the droplet's surface. This is potentially very relevant for researchers investigating scientific questions related to the surfaces and interfaces of different substances," Signorell said. "With all of this work, we hope to fully analyze the broad range of experimental data that can be generated so that we can learn more about the movement of low-energy ."

Explore further: Turmoil in sluggish electrons' existence

More information: "Low-energy photoelectron transmission through aerosol layers," The Journal of Chemical Physics, DOI: 10.1063/1.4983995

Related Stories

Turmoil in sluggish electrons' existence

May 22, 2017

An international team of physicists has monitored the scattering behavior of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

Using lasers to create ultra-short pulses

March 15, 2017

Physicists at Friedrich-Alexander Universität Erlangen-Nürnberg (FAU) have entered new territory with regard to the pulsing of electron beams. Their method could soon be used to develop electron microscopes suitable for ...

Recommended for you

Enhancing the quantum sensing capabilities of diamond

November 22, 2017

Researchers have discovered that dense ensembles of quantum spins can be created in diamond with high resolution using an electron microscopes, paving the way for enhanced sensors and resources for quantum technologies.

Study shows how to get sprayed metal coatings to stick

November 21, 2017

When bonding two pieces of metal, either the metals must melt a bit where they meet or some molten metal must be introduced between the pieces. A solid bond then forms when the metal solidifies again. But researchers at MIT ...

Imaging technique unlocks the secrets of 17th century artists

November 21, 2017

The secrets of 17th century artists can now be revealed, thanks to 21st century signal processing. Using modern high-speed scanners and the advanced signal processing techniques, researchers at the Georgia Institute of Technology ...

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.