A new X-ray microscopy technique that observes molecular-scale features less than a nanometer high has been developed by scientists at the Department of Energy's Argonne National Laboratory (ANL) in collaboration with Xradia, Inc. By combining X-ray reflection with high-resolution X-ray microscopy, scientists can now study interactions at the nanometer scale, where materials often exhibit new properties. A better understanding of interactions at the nanoscale promises to help cure the sick, protect the environment, and make the nation more secure.
This novel technique will lead to a better understanding of interfacial reactions at surfaces, such as ion adsorption, corrosion, and catalytic reactions. In particular, this method extends the capability of X-ray microscopy to observe sub-nanometer-sized interfacial features directly and in real time. This noninvasive approach complements the more widely used scanning probe microscopies and can image the topography of a solid surface without using probe tips near the surface. ANL researchers, together with Xradia, a firm specializing in X-ray optics and X-ray microscope systems, have achieved sensitivity to sub-nanometer-sized features by using a phenomenon known as phase contrast. This breakthrough makes it possible to look directly at individual steps on a solid surface, borrowing a technique used previously in electron microscopy. "The ability to see individual nanometer-scale features is an important benchmark for X-ray microscopy," said ANL physicist Paul Fenter. "Understanding interfacial reactivity is vital to many areas of science and technology, from the corrosion of metals to the transport of contaminants in the environment." "This technique opens up the possibility of watching these processes directly and will provide fundamentally new opportunities for understanding them," added Steve Wang of Xradia. The technique is a significant advance toward understanding the reactivity of solid surfaces. Future studies will extend these measurements to the observation of real-time processes of mineral surfaces in contact with water. Employing a novel X-ray microscope setup developed by Xradia and measurements performed at ANL's Advanced Photon Source, the most brilliant X-ray source in the western hemisphere, was central to the teams' success. The research, funded by the Department of Energy's Office of Basic Energy Sciences, was carried out by a team at ANL's Chemistry Division, including scientists Paul Fenter, Changyong Park, Zhan Zhang, in collaboration with Steve Wang from Xradia. The results were recently published in Nature Physics (Vol. 2, pages 700-704, 2006). Xradia, Inc. is a privately held company established in 2000 to commercialize high-resolution X-ray microscopy systems for nondestructive inspection and nano-scale imaging. For more information, contact Eleanor Taylor, 630-252-5565, etaylor@anl.gov.
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