Quick assessment of a Small 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. This correlative size is calculated from the intersection point between the Guinier and the Porod region, which estimates the radius of a given geometry placed at the same intersection point in the scattering momentum transfer q-axis. The correlative size can be considered a radius for spheroidal or cylindrical objects while a thickness for 2D materials. This methodology could be applied to follow in situ processes like precipitation or polymerization reactions which are usually affected by aggregation, and for the fast analysis of hierarchical structures, where the procedure was also tested for fractal-like structures