A new framework for X-ray photon correlation spectroscopy analysis from polycrystalline materials.

We report a new analytical framework for interpreting data from X-ray photon correlation spectroscopy measurements on polycrystalline materials characterized by strong scattering intensity variations at fixed wavevector magnitude (i.e., anisotropic scattering). Currently, no analytical method exists for the interpretation of the time-dependent anisotropic scattering from such materials. The framework is applied to interrogate the dynamics of a spherical micelle-forming diblock copolymer melt below the order-disorder transition, wherein finite size grains of a micellar body-centered cubic structure produce anisotropic scattering. A wealth of analytical information is recovered from a simple measurement, including distributions of relaxation times and speeds associated with micelles within grains. The findings of this study demonstrate the efficacy of this new analytical method, which may be readily adapted for application to a variety of materials and systems.