Compact 2D Laser Scattering System for Quantitative Structural Analysis in Colloidal Assemblies.

Abstract

Two-dimensional (2D) scattering spectroscopy is a powerful, noninvasive approach for characterizing structural order in colloidal assemblies, yet conventional techniques like small-angle X-ray/neutron scattering face inherent limitations in resolving microscale architecture and require costly, nonportable infrastructure. While visible-light scattering offers a cost-effective alternative for benchtop analysis, its utility is constrained because of multiple scattering in dense media and a limited spatial sampling range. To overcome these challenges, we here develop a compact 2D light-scattering system that integrates polarization filtering to selectively detect single-scattering signals and employs multi-angle illumination to extend accessible scattering angles for probing submicron scales. Based on the single-scattering model, we can extract the structure factor from different isotropic colloidal assemblies with either hard-sphere or electrostatic interactions. By coupling the scattering patterns with molecular dynamics simulations, we can further obtain the particle positions in three dimensions. In addition, this system can be used to resolve anisotropic deformations in elastic colloidal films. This cost-effective, lab-scalable platform offers a robust tool for probing structure-function relationships in colloidal and soft matter systems.