Pinhole mirror-based ultra-small angle light scattering setup for simultaneous measurement of scattering and transmission

An ultra-small angle light scattering setup with the ability of simultaneous registration of scattered light by a charge-coupled device camera and the transmitted direct beam by a pin photodiode was developed. A pinhole mirror was used to reflect the scattered light; the transmitted direct beam was focused and passed through the central pinhole with a diameter of 500 mu m. Time-resolved static light scattering measurement was carried out over the angular range 0.2 degrees <= theta <= 8.9 degrees with a time resolution of similar to 33 ms. The measured scattering pattern in the q-range between 5 x 10(-5) and 1.5 x 10(-3) nm(-1) enables investigating structures of few micrometers to submillimeter, where q is the scattering vector. A LabVIEW-based graphical user interface was developed, which integrates the data acquisition of the scattering pattern and the transmitted intensity. The Peltier temperature-controlled sample cells of varying thicknesses allow for a rapid temperature equilibration and minimization of multiple scattering. The spinodal decomposition for coacervation (phase separation) kinetics of an aqueous mixture of oppositely charged polyelectrolytes was demonstrated. Published by AIP Publishing.

Automated summary

An ultra-small angle light scattering setup was developed for simultaneous registration of scattered light and transmitted direct beam. With a LabVIEW-based graphical user interface, this setup enables structural investigations and provides rich data for kinetic processes.