A Streamlined Approach To Structure Determination

TECH SPACE

Argonne IL - Apr 13, 2004
Researchers at the U.S. Department of Energy's Argonne National Laboratory have taken the guesswork out of interfacial structure determination. Their work is published in the April 10 issue of Surface Science Letters.

Argonne researchers have directly visualized, in three-dimensions, ion site distributions at the mineral-water interface using a technique called X-ray standing wave (XSW) imaging. Their finding demonstrates a new capability for revealing complex reactions at mineral-water interfaces that previously could be understood only through more indirect approaches.

XSW, in contrast to X-ray crystallography, measures both the amplitude and phase information that completely describe the molecular-scale structure of interest. In standard crystallography only the amplitudes can be measured and consequently an elaborate approach is needed to determine the structure.

"We are the first to show that images of the atom site distributions can be directly obtained with XSW. In this case of adsorption at the mineral-water interface, we were able to fully resolve ion-specific sorption sites and distinguish different coordination environments for each ion," said Paul Fenter of Argonne's Environmental Research Division.

The XSW imaging approach allows scientists to streamline the tedious process of structure determination. "With XSW imaging, data acquisition and analysis can be completed in less than 24 hours. Previously, surface structure determination would take weeks or months to complete" said Fenter.

Authors on the report, in addition to Fenter, are Zhan Zhang of Northwestern University, Likwan Cheng of Argonne, Neil Sturchio of the University of Illinois at Chicago and Argonne, Michael Bedzyk of Northwestern University and Argonne, Michael Machesky of the Illinois Water Survey, and David Wesolowski of Oak Ridge National Laboratory.

Solid-liquid interface structure is essential to many natural and technological processes. The interaction of mineral surfaces with fluids controls rock weathering, evolution of petroleum reservoirs and ore deposits, and the transport and remediation of contaminants in groundwater aquifers. "Our long term goal is to learn how to use X-rays to 'see' geochemical processes in action at the molecular level," said Fenter.

The research was conducted at the Basic Energy Sciences Synchrotron Radiation Center at the Advanced Photon Source (APS) at Argonne. The APS, which produces the most brilliant X-rays for research in the Western Hemisphere, is ideal for this type of research. "The APS brilliance allows us to illuminate a small, nearly-perfect region of a larger imperfect crystal and still be able to do the measurement," said Fenter.

TECH SPACE

Time-Reversal Acoustics Research Promises Medical Breakthroughs

Hoboken NJ - Apr 08, 2004
Scientists have not yet found a way to actually make time run backward, but in the cutting-edge world of recent acoustics research, they have shown a way to make sound waves run backward in a kind of ultra-focused reverse echo. By the technology known as time-reversal acoustics, sound waves - in exact reverse order from the original sound - echo directly and very precisely back to their source point.

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.