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|Posted: Fri Sep 05, 2008 1:30 pm Post subject: World's Most Powerful Microscope Arrives at Berkeley Lab
|14 January 2008 mercurynews.com
World's Most Powerful Microscope Arrives at Berkeley Lab
by Betsy Mason
The science of small just got a lot bigger at Lawrence Berkeley National Laboratory with the arrival of the world's most powerful microscope.
The new $27 million microscope has a resolution of half of an angstrom, or 300 billionths of a foot, and can image and identify individual atoms.
"It's doubling the resolution of the best microscope we have here," said materials scientist Ulrich Dahmen, director of the National Center for Electron Microscopy at the lab. "It's beyond the state of the art."
To put the power of the half-angstrom resolution in perspective, atoms are usually spaced a couple of angstroms apart. Human fingernails grow at about 10 angstroms per second, the same speed at which the earth's tectonic plates move.
"It can see finer detail than any other machine," said John Spence, a physicist at Arizona State University in Phoenix. "You can see atoms better."
The microscope will help scientists discover and shape new atomic-scale nanostructures that could lead to better materials for a whole range of products from airplanes to cosmetics.
Another possibility that could potentially save billions of dollars is the use of nanoparticles to help convert oil into gasoline, Spence said.
"The job they do depends on how the atoms are arranged," he said. "You could tweak them to do the conversion more efficiently."
The microscope project, funded by the Department of Energy, is the first large-scale microscope project of its kind. It's a collaboration of several national labs as well as two European companies that built the microscope.
The first phase of putting the instrument together in Berkeley was completed last month. Dahmen hopes to be able to test it in a month or so, once it has been calibrated. Later this year, the microscope will be available to scientists around the world who apply to use it.
Standing 12 feet tall, the new electron microscope has made several technological leaps over the rest of the world's microscopes to improve resolution, contrast and color.
Electron microscopes work by shooting a beam of speeding electrons at a thin slice of material, then recording how the material scatters the electrons.
One of the major improvements is a series of more than a dozen magnetic lenses that help focus the electron beam. As the particles pass through the lenses, magnets push and pull them into the right place until they are focused into a single point when they hit the target material.
"It's a way of repositioning the electrons," said physicist Peter Denes, the microscope project manager. "It takes a lot of these lenses to do that."
The material scatters the electrons, and another series of lenses then pulls the electrons back into an image.
Each lens has its own power source, which must be incredibly stable with no fluctuations. The technology behind the new microscope's power sources was developed only last year.
Looking at things as small as an atom requires an extremely quiet, stable environment. At Lawrence Berkeley Lab, the new machine rests on a 70-ton concrete block that rides on air cushions to reduce interference from ground vibrations.
The room that houses the microscope will be sealed off with no air flow and no noise interference, and held at a constant temperature. It has slanted walls to reduce acoustic noise, is separated from the rest of the building that surrounds it and cost $1 million to construct.
"We've gone to a great deal of trouble to create a stable environment," Dahmen said.
The next stage of the project is construction of a second microscope at the lab that has all the capabilities of the first, with some additional improvements. The second instrument will have lenses that correct for color.
Just as images on old television sets sometimes have a halo of color around them, electron microscope images have a color fringe that blurs the detail. The second machine will be the first in the world to correct this problem. Another important improvement will be the ability to rotate the material being imaged to see it from different angles.
"We're on the verge of visualizing atomic images in three dimensions," Spence said. "In the past, electron microscopes have always shown a projection, a two-dimensional image."
The result will be the ability to map out exactly where every atom is in a material, a long-sought-after feat.
The full capability of the second microscope probably won't be known until it is finished in 2009.
"Judging from the tests we've done, there will be a whole range of things we hadn't even thought of," Dahmen said.
Story posted: 14th January 2008