Kirkland microscopes can examine matter one atom at a time
A Kirkland company is pushing the scientific frontier by building electron microscopes capable of seeing and identifying every atom in thin sheets of material.
Seattle Times science reporter
X-ray vision was state-of-the-art when Superman launched his career in the 1930s.
But if the superhero wants to keep pace with the modern world of nanotechnology, he should upgrade to electron vision, Ondrej Krivanek says.
Tapping the technology at the heart of the electron microscope would allow the Man of Steel to not only see through things, but also to peer into their very substance — all the way down to their atoms.
Clark Kent couldn't turn to many places for a discreet retrofit, but Krivanek's 12-person Kirkland company, Nion, probably could handle the job. Since 1997, Nion has been retrofitting electron microscopes around the world to sharpen their vision. Now, the team is pushing the frontier of microscopy with new instruments capable of seeing and identifying every atom in thin sheets of material.
"It's a big breakthrough," said materials scientist Jian-Min Zuo, of the University of Illinois, Urbana-Champaign, who wasn't involved in the work. "To understand the properties of nanomaterials, we have to know their atomic structure."
The prowess of Nion's microscopes was featured on the cover of the journal Nature this spring. The lead image clearly shows individual atoms arrayed in a lattice of rings, glowing like Christmas lights.
"It is quite mind-boggling," said Stephen Pennycook, leader of Oak Ridge National Laboratory's electron microscopy group and a longtime Nion collaborator. "This was new territory for microscopy."
Since the first electron microscopes were built nearly 80 years ago, scientists have clamored for higher resolution. That quest was hampered by a flaw some thought might be unfixable: inherent aberrations, similar to those that fogged the vision of the Hubble Space Telescope before its repair.
"We were getting blurry images, and we had to do a lot of interpretation to try and understand what they were," said Rutgers University researcher Philip Batson, who was Nion's first customer.
In a conventional microscope, aberrations can be fixed by honing the glass lenses that focus light.
But aberrations are much harder to correct in electron microscopes, which work by scanning an object with a narrow beam of electrons, then analyzing the way the electrons scatter or interact with the sample to generate a magnified image. Instead of glass lenses, magnetic fields do the focusing.
The 1936 scientific paper that first described the aberration problem fills more than 20 pages with dense mathematical formulas. Some of the early attempts at a fix resulted in machines with 100 knobs, each of which required adjusting to focus the image. With little progress to show for their efforts, science agencies eventually stopped funding research.
"They put it in the filing cabinet labeled 'impossible projects' and decided to just forget about it," Krivanek said.
When he and his partner, Niklas Dellby, set out to tackle the aberration problem in the early 1990s, the only money they could scrape up was a $120,000 grant from the U.K.'s national science academy. The pair moved to Cambridge, where they lived on savings and spent the next 18 months hacking apart an electron microscope and adding a Rube-Goldberg-esque tower of magnetic correctors.
They were aided by powerful laptop computers and advanced electronics that earlier researchers lacked.
With its first crude corrector in hand, the team set up shop in a nondescript Kirkland business park — largely because Krivanek held a research appointment at the University of Washington.
Batson then was working for IBM, where semiconductors reigned supreme. He bought Nion's first commercial version of a corrector to analyze silicon compounds, where a single misplaced atom can undermine the efficiency of electronic components.
"Being able to see the atoms is the best way we know of being able to understand why materials behave the way they do," he said.
Nion's correctors, and those produced by a German firm, boosted the resolution of electron microscopes about threefold over the next several years. The best machines now can see objects smaller than an angstrom — one ten-billionth of a meter, and roughly the size of an atom.
But retrofitting an old microscope with aberration correctors is like cramming a Ferrari engine into a Ford Escort. The chassis wasn't built for a level of performance where even the slightest wobble blurs the focus.
So Krivanek and Dellby decided to build microscopes from the ground up. The version used for the analysis featured in Nature is called UltraSTEM (for scanning transmission electron microscope).
"It's a wonderful machine," said Pennycook, who oversees one of the world's biggest collections of electron microscopes at Oak Ridge.
The Nion team wasn't the first to see individual atoms. That was accomplished in the 1970s — but only with heavy, single atoms, such as uranium. Since then, other scientists have resolved atoms in a material but have not been able to distinguish one type from another.
Working with the UltraSTEM, Krivanek and colleagues were able for the first time to clearly distinguish small atoms bonded side by side in a material — in this case, a film of boron nitride one atom thick. Each type of atom glowed with a different intensity.
"You can figure out what you have just by looking at the brightness of the dots," Krivanek said.
The ability to see small atoms such as carbon and oxygen opens the door to the study of potential drugs and the structures and molecules inside cells. Some scientists believe nanospheres of gold could be used to ferry anti-cancer drugs directly into tumors — and high-resolution microscopy could help design the packages.
It also enables detailed analysis of substances such as graphene — the ultrathin sheets of carbon that may far surpass silicon-based electronics — if researchers can figure out how to make them work.
Uncorrected electron microscopes not only have a hard time resolving small atoms and delicate materials — they destroy them with the high-energy electron beams necessary to reduce fuzziness.
"The ultimate bugbear in electron microscopy is that while you're looking at a sample, you may be damaging it," Krivanek said.
The built-in correctors in Nion's microscopes allow them to operate with gentler electron beams.
But Nion microscopes aren't about to flood the market. It takes nine months to build each instrument, and the price tag is around $3 million. The company has delivered four, and a fifth is ready to be shipped to a French research lab.
With a grant from the National Science Foundation, Krivanek and Batson already are at work on the next generation.
"We want to improve the resolution even more," Krivanek said. "It never stops."
Sandi Doughton: 206-464-2491 or email@example.com
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