Nanoparticle characterization by continuous contrast variation in SAXS with a solvent density gradient

TL;DR

This paper introduces a novel SAXS contrast variation method using a solvent density gradient to analyze the internal structure of low-density nanoparticles, providing detailed size and electron density insights.

Contribution

It presents a new contrast variation technique with a solvent density gradient in SAXS for resolving nanoparticle internal morphology.

Findings

Determined nanoparticle size and distribution using isoscattering points and Guinier analysis.

Corroborated results with a model fit revealing internal electron density distribution.

Successfully characterized low-density nanoparticle internal structure.

Abstract

Many low-density nanoparticles show a radial inner structure. This work proposes a novel approach to contrast variation with SAXS based on the constitution of a solvent density gradient in a glass capillary in order to resolve this internal morphology. Scattering curves of a polymeric core-shell colloid were recorded at different suspending medium contrasts at the four-crystal monochromator beamline of PTB at the synchrotron radiation facility BESSY II. The mean size and size distribution of the particles as well as an insight into the colloid electron density composition were determined using the position of the isoscattering points in the Fourier region of the scattering curves and by examining the Guinier region in detail. These results were corroborated with a model fit to the experimental data, which provided complementary information about the inner electron density distribution of the suspended nanoparticles.