ULTRA-SMALL-ANGLE X-RAY-SCATTERING TO BRIDGE THE GAP BETWEEN VISIBLE-LIGHT SCATTERING AND STANDARD SMALL-ANGLE SCATTERING CAMERAS

This paper reports the performance of an ultra-small-angle X-ray scattering facility on beamline X23A3 at the National Synchrotron Light Source. Based on a Bonse-Hart double-crystal design, the instrument combines: continuously tunable optics with asymmetric first monochromator crystal, high-flux throughput, high-precision crystal rotators, independently-mounted reflecting crystals, photodiode detector and high-resolution X-ray video camera. This combination of features permits rapid small-angle X-ray scattering measurements in the scattering wave-vector range of 0.005-2.0 nm-1 (depending on the sample), with mum-positioning accuracy of a typical 3 x 3 mm2 beam on the sample.