Overview of Small Angle Scattering at the Advanced Photon Source. P. Thiyagarajan¹, R. K. Crawford¹, K. A. Carrado², D. M. Tiede² and R. E. Winans², ¹Intense Pulsed Neutron Source Division, ²Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA., Fax: 630-252-4163, e-mail: Thiyaga@anl.gov

The high brilliance of x-rays available on the undulator beamlines at the Advanced Photon Source (APS) provides exciting new opportunities in small angle scattering applications in a wide range of scientific disciplines. The highly collimated and intense x-ray beams will permit access to very low scattering angles and thus it will be possible to probe larger length scales on shorter time scales. By using an area detector SAXS data can be measured in a wide scattering vector range and this will enable time-resolved SAXS studies on dynamic systems (phase transitions, excited states etc.). The tunability of the undulator source in the 2-40 keV energy region will be very effective for anomalous SAXS studies wherein contrast variation can be achieved by varying the energy of the probing x-rays in the SAXS measurements. This energy range contains absorption edges for all of the elements from P to U, either by using their K or L3 edges. These studies will provide unique species specific structural information in systems such as organometallics, ceramics, zeolites, supramolecular complexes and metallic alloys. The beams from the undulator sources also contain significant amounts of coherent x-rays that can be used to study the dynamics of macromolecules by using intensity fluctuation spectroscopy. The characteristics of x-rays from the undulator beamline at Argonne's Basic Energy Sciences Synchrotron Research Center as applicable to small angle scattering applications will be discussed.

Work was performed under the auspices of Office of Basic Energy Sciences, US Department of Energy, under the contract number W-31-109-ENG-38 to the University of Chicago.