Enhancing Polymer Characterization with Algorithmically Refined DFT Optical Models in Polarized Resonant Soft X-ray Scattering

Polarized resonant soft X-ray scattering (pRSoXS) is a powerful tool for nanoscale characterization of molecular orientation through polarized X-rays, but accurate interpretation of scattering data requires robust optical models that account for the polarization-dependent interactions involved. In this work, we present an algorithmically refined optical model that integrates density functional theory (DFT) calculations with experimental absorption spectroscopy, allowing us to trace individual resonances to specific quantum mechanical transitions within molecules. To validate the predictive capabilities of this model, we employ the model in polarized X-ray reflectivity measurements of molecular films with known orientation. In particular, we analyze crystalline thin films of Zinc Phthalocyanine (ZnPc) and naphthalene diimide-thiophene copolymers, where molecular orientation is controlled through deposition parameters and verified using grazing incidence wide-angle X-ray scattering (GIWAXS). Our refined optical model significantly enhances the interpretation of pRSoXS data, enabling more accurate characterization of polymer structures at the nanoscale. This advancement not only improves data analysis and interpretation but also facilitates a deeper understanding of polymer structure–property relationships, which is crucial for developing new materials with tailored functionalities.