Quick assessment of a Small-Angle Scattering data using Guinier-Porod model: Introducing the correlative size

A straightforward method is proposed to process the non-linear parameters obtained from Guinier-Porod (GP) functions, commonly used for a fast evaluation of Small-Angle Scattering (SAS) data. The GP function could be used for a first structural assessment before selecting a specific model or to use as it is depending on the complexity of the system. However, functions are highly-non-linear, so parameters from the model are strongly correlated, hence, releasing all parameters free for fitting may lead to data interpretation pitfalls. In this work, a correlative size is introduced in order to avoid numerical artifacts and simplify the comparison between samples. To address this, we introduce a correlative size metric based on the intersection point between the Guinier and Porod regions. This reference point provides a geometry-independent way to compare scattering features, yielding an effective radius for spheroidal and cylindrical objects or a thickness for bidimensional systems. This methodology could be applied to follow in situ processes like precipitation or polymerization reactions which are usually affected by aggregation, polydispersity or the interference of byproducts, and for the fast analysis of hierarchical structures, where the procedure was also tested for fractal-like structures.