Statton Camera: Small- and Wide- Angle X-Ray Scattering

Statton Camera

The Statton camera produces a point-collimated x-ray beam via two pinholes (100 - 500 micron diameter) separated by approximately 15 cm; it employs CuKα x-rays, from the point port of a sealed tube (PANalytical PW2773/20, powered by a PW3830 generator). Monochromatization is achieved with a pyrolitic graphite monochromator (Huber 151) upstream of the pinholes. The camera was designed by W.O. Statton of DuPont in the 1950s to acquire WAXS and SAXS patterns from fibers; our unit is equipped with a hot stage for variable-temperature measurements. Originally designed for use with x-ray film, we have replaced the film with Kodak image plates (storage phosphors). These plates are read with a GE Healthcare Typhoon FLA 7000 scanner, directly yielding a digital scattering pattern with a dynamic range of approximately 105. The near-parallel nature of the x-ray beam conveniently allows for the simultaneous collection of SAXS and WAXS data from the same location on the specimen. Sample SAXS and WAXS patterns are shown below.

Simultaneous 2-D SAXS and WAXS patterns
Simultaneous 2-D SAXS (left) and WAXS (right) patterns of a flow-aligned semicrystalline diblock copolymer that forms nanoscale cylinders of poly(vinylcyclohexane) in a matrix of polyethylene. The patterns were acquired with the x-ray beam perpendicular to the cylinder axis. Spots on the meridian in the SAXS pattern indicate that the cylinders are aligned along the equator. The WAXS pattern reveals preferential crystal orientation in the matrix, with a four-spot polyethylene (110) reflection (red spots) and a two-spot (200) reflection on the meridian. The azimuthal positions of the spots indicate that the polyethylene crystals grow parallel to the cylinder axis (Loo et al., Macromolecules, 33, 8361 (2000)).