SAMM TO BOOST MICROSCOPY CAPABILITIES
25 March 2007 - DOE/Argonne National Laboratory

SAMM will be a user facility, open to researchers at Argonne and from industry and academia. Its powerful electron microscopes will give researchers atom-scale views of the structure of materials, with a focus on nanoscience. Nanoscale materials, consisting of particles just a few molecules across and measured in billionths of meters, often have enhanced properties when compared to the materials in bulk.

“Electron microscopes are natural instruments for nanoscience,” said George Crabtree, director of Argonne's Materials Science Division. “They have the best resolution of any of the scattering probes: You can get down to imaging a single atom, Angstrom resolution. Therefore they are very effective for probing nanoscale structures.”

The new center will make the power of electron scattering more widely available for forefront materials science. Electron microscopy's higher spatial resolution for imaging and diffraction are natural complements to Argonne's other user facilities, the Advanced Photon Source and the Intense Pulsed Neutron Source. Argonne is unique in having facilities for electron, X-ray and neutron scattering facilities at the same site.

Nanoscience is one driving factor behind the SAMM facility. But in addition to studying materials, researchers at SAMM will design, build and operate a new kind of electron microscope, part of a national effort to develop a Transmission Electron Aberration-corrected Microscope. One of the four microscopes at SAMM will be the prototype TEAM instrument.

“The vision is to use TEAM to dramatically enhance the impact of electron microscopy on materials science,” Crabtree said. “This will define the next generation of electron microscopes.”

The TEAM project aims to achieve a resolution of 0.5 Angstrom, about one million times smaller than the diameter of a human hair, by the end of the decade. Another objective is to acquire three-dimensional images at atomic resolution. Today's best microscopes can only produce three-dimensional images at much lower resolution.

The substantial expense of developing and maintaining such aberration-corrected electron microscopes is beyond the ability of individual investigators or even university centers. Argonne is teaming with Brookhaven, Lawrence Berkeley and Oak Ridge national laboratories and the Frederick Seitz Materials Research Laboratory at the University of Illinois at Urbana-Champaign to develop the concept. Argonne scientists and engineers are designing the “ultracorrector,” the electron lens system at the heart of the new approach. Once developed, the TEAM concept will be transferred to commercial manufacturers.

“In addition to improved resolution, aberration correction offers increased experimental space around the sample and the ability to penetrate, with a minimum loss of resolution, a thicker sample,” said Dean Miller, director of Argonne's Electron Microscopy Center. “We can use this ability to examine samples inside a gas reaction cell, for example, to analyze catalysis, corrosion or oxidation processes.”

Researchers will also study ferroelectric materials, substances with internal electric fields, and will be able to watch nanoscale material self-assembly processes.

“We'll be able to conduct experiments in situ, where we can watch the sample respond in real time to external conditions like changing magnetic fields,” Miller said. “Doing experiments inside the microscope, while you're watching, will be groundbreaking.”

New types of sample holders will be developed to enable these in-situ experiments.

Microscopes of this precision are incredibly sensitive to their environment, Miller said, so the SAMM Building will require special construction techniques and utilities. The microscopes can be affected by electrical systems in the building, ground vibrations, variations in temperature and other factors.

“We have all kinds of ways to measure magnetic fields, acoustics and other factors, but the microscopes that we put in the building will be the most sensitive detector of their environment, more sensitive than the things we can use to measure it,” Miller said.

For example, the body heat of the operators, and even their voices, can affect the microscope's resolution. Operators will operate the microscopes remotely from separate rooms. Each instrument will sit on its own floor slab, decoupled from the walls, with a specially engineered base to attenuate vibrations.

The SAMM facility was designed using the existing drawings and specifications for a similar facility at Oak Ridge National Laboratory resulting in significant cost savings. DOE's Office of Basic Energy Sciences supplied $2.5 million toward the design and construction of the $4.5 million facility. SAMM should be ready for operation by summer 2006.

The nation's first national laboratory, Argonne National Laboratory conducts basic and applied scientific research across a wide spectrum of disciplines, ranging from high-energy physics to climatology and biotechnology. Since 1990, Argonne has worked with more than 600 companies and numerous federal agencies and other organizations to help advance America's scientific leadership and prepare the nation for the future. Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy's Office of Science.

http://www.anl.gov

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