MRS Bulletin

Technical Feature

Technical Feature

High-Resolution 3D Imaging Microscopy Using Hard X-Rays

Christian G. Schroer, Peter Cloetens, Mark Rivers, Anatoly Snigirev, Akahisa Takeuchi and Wenbing Yun

Abstract

The key strength of hard x-ray full-field microscopy is the large penetration depth of hard x-rays into matter, which allows one to image the interior of opaque objects. Combined with tomographic techniques, the three-dimensional inner structure of an object can be reconstructed without the need for difficult and destructive sample preparation. Projection microscopy and microtomography are now routinely available at synchrotron radiation sources. The resolution of these techniques is limited by that of the detector to 1 µm or slightly less. X-ray images and tomograms at higher spatial resolution can be obtained by x-ray optical magnification, for example, by using parabolic refractive x-ray lenses as a magnifying optic. Combining magnifying x-ray imaging with tomography allows one to reconstruct the three-dimensional structure of an object, such as a microprocessor chip, with resolution well below 1 µm. In x-ray scanning microscopy, the sample is scanned through a small-diameter beam. The great advantage of scanning microscopy is that x-ray analytical techniques such as fluorescence analysis, diffraction, and absorption spectroscopy can be used as contrast mechanisms in the microscope. In combination with tomography, fluorescence analysis makes it possible to reconstruct the distribution of different chemical elements inside an object (fluorescence microtomography), while combining absorption spectroscopy with tomography yields the distribution of different oxidation states of atomic species.

Keywords

  • hard x-rays;
  • three-dimensional imaging microscopy;
  • tomography

Christian G. Schroer is a research and teaching associate at the Institute of Physics II at Aachen University. His scientific interests include hard x-ray microscopy and microtomography in full-field and scanning mode, combining x-ray analytical methods with high-resolution imaging. At the heart of his research lies the development of refractive x-ray lenses. Schroer performed his doctoral studies in mathematical physics at Forschungszentrum Jülich (doctoral degree, University of Cologne). After a postdoctoral fellowship at the University of Maryland, he began his present position at Aachen University, where he has pursued research since 1998.

Schroer can be reached at II Physikalisches Institut, Aachen University, D-52056 Aachen, Germany; tel. 49-241-8027089, fax. 49-241-8022306, and e-mail schroer@physik.rwth-aachen.de.

Peter Cloetens is a research scientist in the Imaging Group at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. His research involves microtomography, where his main interest is quantitative three-dimensional imaging in both absorption and phase contrast mode, with application to topics in materials and the life sciences. He has implemented a highresolution absorption and phase contrast tomography station at the ID19 imaging beamline at the ESRF, and his recent work has extended hard x-ray imaging to the deep-submicrometer domain by means of a nanoprobe. Cloetens received his PhD degree from the Department of Applied Sciences of the University of Brussels (VUB) in 1999 with research in the field of phase contrast imaging using hard synchrotron x-rays.

Cloetens can be reached at the European Synchrotron Radiation Facility (ESRF), BP 220, F-38043 Grenoble, France; tel. 33-(0)47688-2650, fax 33-(0)47688-2020, and e-mail cloetens@esrf.fr.

Mark Rivers is a senior scientist in the Department of the Geophysical Sciences and the Center for Advanced Radiation Sources at the University of Chicago. He is also co-director of the GeoSoilEnviroCARS sector at the Advanced Photon Source at Argonne National Laboratory. GSECARS provides a wide range of synchrotron techniques to problems in earth, planetary, and environmental sciences. Rivers directs the microtomography facility at GSECARS. Together with Stephen Sutton and Keith Jones, he built the world's first dedicated synchrotron x-ray microprobe at the National Synchrotron Light Source at Brookhaven National Laboratory, starting in 1983. He obtained his PhD degree in geology and geophysics at the University of California—Berkeley, where he studied the sound velocities of silicate melts.

Rivers can be reached GSECARS-APS, 9700 South Cass Ave., Bldg. 434A, Argonne National Laboratory, Argonne, IL 60439, USA; tel. 630-252-0422, fax 630-252-0436, and e-mail rivers@cars.uchicago.edu.

Anatoly Snigirev is a staff scientist in the Experiments Division at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. His scientific interests include novel x-ray optical devices, high-energy x-ray microscopy, and coherent imaging techniques. He received his PhD degree in solid-state physics from the Russian Academy of Sciences in Chernogolovka in 1986 in the area of dynamical x-ray diffraction by crystals. Between 1986 and 1993, he was a scientist and then a head of the X-Ray Crystal Optics Group in the Institute of Microelectronics Technology of the Russian Academy of Sciences. In 1990, he was an Alexander von Humboldt Foundation scholar with U. Bonse at Dortmund University. He became a beamline scientist at the ESRF in 1993 and a staff member in 1996. Snigirev can be reached at the European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble, France; tel. 33-(0)4-76-88-2627, fax 33-(0)4-7688-2542, and e-mail snigirev@esrf.fr.

Akihisa Takeuchi is a beamline scientist in the Life and Environmental Science Division of the SPring-8 Japan Synchrotron Radiation Research Institute. His research interests are in x-ray optics and microimaging using x-ray optical devices such as Fresnel zone plates and Kirkpatrick–Baez mirrors. He received his PhD degree in engineering physics from the University of Tsukuba in 1999.

Takeuchi can be reached at the Life and Environmental Science Division, JASRI/SPring-8, 1-1-1 Kouto Mikazuki-Cho Sayo-Gun Hyogo, 679-5198 Japan; tel. 081-(0)791-58-833, fax 081-(0)791-58-0830, and e-mail take@spring8.or.jp.

Wenbing Yun is president and founder of Xradia Inc., a private company specializing in novel applications of x-ray microfocusing optics for high-resolution nondestructive imaging, materials characterization, and medical and biomedical research. He was responsible for the development of x-ray microfocusing optics and the three-dimensional tomography program at Lawrence Berkeley National Laboratory from 1998 to 1999, where he developed the x-ray imaging microscope using a zone plate as an objective in the 4–10 keV x-ray region. From 1991 to 1998, he was the leader of the x-ray microscopy group at the Advanced Photon Source at Argonne National Laboratory, where he developed highperformance x-ray zone plates for 2–50 keV x-ray applications and an x-ray microprobe that received the 2000 R&D 100 award. He received his PhD degree from the State University of New York at Stony Brook. Yun can be reached at Xradia Inc., 4075 Spring Dr., Concord, CA 94520, USA; tel. 925-288-1228, fax 925-288-0310, and e-mail wyun@xradia.com.

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