By Marlene Cimons, National Science Foundation
Scientists at Rutgers University and a small Washington State company are collaborating on a state-of-the-art electron microscope that will produce an electron beam as tiny as the size of a hydrogen atom—the smallest atom known—and can study the inner workings of materials important in creating new sources of renewable energy.
Unlike existing electron microscopes, the novel instrument will be able to measure vibrations and energy produced and absorbed by the material under examination—information critical to understanding how the material will behave when it is used in manufacturing new devices.
The microscope is an "aberration corrected" electron microscope, a sophisticated system that corrects for lens distortions, until recent years a serious problem.
"We are developing new techniques that, hopefully, will enable industries important to energy self-sufficiency in the United States," said Philip Batson, research professor at the Institute for Advanced Materials, Devices and Nanotechnology at Rutgers. "And we're doing it with a small U.S. company in an area that has thus far been dominated by companies outside the United States."
Rutgers is working with the Nion Co., one of two companies, and the only one in the United States, capable of manufacturing aberration-corrected optics. "It's very hard to do, and we've only just begun to learn how to do it," Batson said.
The work is being funded by a $2 million grant from the National Science Foundation as part of the American Recovery and Reinvestment Act of 2009.
Electron microscopes have been in use since the 1930s, when researchers began to look at objects using electrons, instead of light. But, unlike lenses for light, electron lenses produce severe distortions, a problem that has only begun to be correctable since the late 1990s.
"The result has been a sea change in the electron microscopy, from being unable to see the atomic structure in a direct way to being able to see even single atoms moving around," Batson said.
Moreover, when material is examined using the microscope "we transfer energy to the material when we hit it with electrons—the whole material wiggles in various ways," he said.
Understanding how the material absorbs energy, whether from electrons or light, "is absolutely crucial to understanding how a particular nanoscale object will function when we try to use it to make a device,'' Batson said, adding that applications could include making electrical power from sunlight, and producing hydrogen from water using photo-active catalysts.
"Electron microscopy is arguably the premier analytical tool used in science today, because it provides us with atomic level structure," Batson said. "But, to date, it has not been capable of measuring the very small vibrations and wiggles important to how the material functions. The new microscope will be the first one capable of directly measuring the energy absorbed by these vibrational excitations," he added.
The microscope uses a technique known as "electron energy loss spectroscopy" to measure the energy lost by the electrons in the material, and, based on that information, can aid scientists in figuring out how the material behaves.
"Imagine that the material is a bed spring, and we hit it with a baseball at 100 miles an hour, the baseball would be deflected a little bit, and the bedspring would vibrate," Batson explained. "We can catch the baseball, analyze how its direction has changed, how much energy it has lost, and use that to figure out how the bedspring absorbed the energy lost by the baseball."
The new instrument will enable scientists to measure this "a lot better than anybody has ever done before," Batson said. "There's a whole range of energies we can give up to the material. Some are very small, but very important to energy-related applications."
Information from the new microscope will better enable the harvesting of light in designing and making new photovoltaics and photocatalysts, he said. It also will improve scientists' understanding of how atomic structure influences electrical conduction, he said.
Furthermore, "it will be ideally suited to help clarify new types of interaction of light with materials, for instance, the recently discovered ‘negative index of refraction' in nanoscale metal structures," he said.
"We can't look at materials directly with light at the atomic level," he added. "But using electrons, we can see the atomic structure, and, with this new instrument, measure how the materials absorb energy, allowing us to predict how this would happen with light. The result will be a powerful new way to discover the functional behavior of new materials, hastening our search for better renewable sources of energy."
---
Follow U.S. News Science on Twitter.
Reader Comments