Bernd Kabius has an intimate knowledge of the new transmission electron microscope recently acquired by Penn State's Materials Research Institute. He helped create it. More specifically, he was part of the team that developed the double aberration corrected TEM, an instrument similar to the new FEI Titan housed in a quiet lab in the Millennium Science Complex. As a member of that team, his task was to come up with applications and design the science experiments that would showcase the possibilities of aberration correction on the high-powered instrument.
It is the nature of both optical and electron microscopes to focus their beams using curved lenses. One of Kabius' former colleagues described the quality of electromagnetic lenses used for electron microscopes as being like the bottom of a wine bottle. "It magnifies a little bit, but the imaging quality is terrible," says Kabius. "The physics sets limits that you cannot get around. So these lenses can only be built to a certain level, and that level is bad."
Kabius worked on the two types of aberration correction incorporated into the Titan, first spherical aberration correction at the European Molecular Biology Laboratory in Heidelberg, Germany, and in the next decade chromatic aberration correction at the Electron Microscopy Center at Argonne National Laboratory. Like adding two sets of eyeglasses to the lenses, these components focused the electron beam to minimize information delocalization by a factor of 10. In addition, current density is greatly enhanced, which improves sensitivity, he says. The new Helios focused ion beam system in the Materials Characterization Laboratory will make better samples for even higher quality imaging in the Titan.
With a resolution capability of 0.5 angstrom, about twice the radius of the smallest atom, TEM has reached its foreseeable limit, Kabius believes. "There are no projects ongoing to try to improve that. It would cost $30 million to get to 0.3, and nobody knows for what." That doesn't mean that TEM development is at an end. In the last two decades there has been a flurry of innovations in new components that can be placed inside the instrument to allow for new science experiments to be performed and observed in place. "With these components, I believe the mainstream for the next decade will be in situ experimentation," he predicts.
One immediate benefit of this approach could be observing a catalytic reaction under the electron beam as it is occurring and in a controlled environment. "You cannot get the information to improve the reaction if you look at it after it has happened and not in its environment," he states. "In situ chemical reactions are a big topic in science." The new capabilities available with in situ TEM will benefit researchers in chemistry, physics, electrical engineering, mechanical science, and materials, Kabius says.
However, only a few small companies are making these experimental components, called stages, for in situ experimentation. Kabius sees this as an opportunity to partner with these companies and Penn State's Nanofabrication Laboratory to build new stages that don't currently exist. This is an area in which Penn State could create a unique capability, he believes.
"When we first got these incredible instruments, we only wanted to look at images," Kabius recalls. "But now we want to get more quantitative information. Penn State has the qualities required to move this field ahead: great scientists with great ideas, a great microscope, and people with expertise in theory to match our experiments."
Kabius is a senior scientist in the Materials Research Institute. He comes from the Environmental Molecular Sciences Laboratory, a part of Pacific Northwest National Laboratory, where he was lead microscopist.
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