Ultra-small-angle X-ray scattering–X-ray photon correlation spectroscopy: a new measurement technique forin situstudies of equilibrium and nonequilibrium dynamics

Abstract

Ultra-small-angle X-ray scattering-X-ray photon correlation spectroscopy (USAXS-XPCS) is a new measurement technique for the study of equilibrium and slow nonequilibrium dynamics in disordered materials. Taking advantage of Bonse-Hart crystal optics, this technique fills a gap between the accessible scattering vector ranges of dynamic light scattering and conventional X-ray photon correlation spectroscopy. It also overcomes the limits of visible light scattering techniques imposed by multiple scattering and is suitable for the study of optically opaque materials containing near-micrometer sized structures. USAXS-XPCS has been applied to study the equilibrium dynamics of micrometer-sized colloidal dispersions and nonequilibrium dynamics of polymer composites and alloy steels. We anticipate that this technique will be important in the understanding of thermallyinduced equilibrium dynamics of soft materials and nonequilibrium behavior of both soft and hard materials, and lead to technical payoffs in a wide range of areas such as the manufacture of advanced ceramic and metallurgical materials and self-repairing biologically critical materials.