High-Quality Small-Angle X-ray Scattering (SAXS) Measurements on a Powder X-ray Diffractometer

Introduction

Small-angle X-ray scattering (SAXS) is an analytical technique that measures X-rays scattered from a sample at small angles, usually below 10° 2θ. It provides sample properties such as the size distribution of polydisperse samples, the size and shape of monodisperse samples, average distances in weakly ordered samples, and the arrangement of nanoscale structures within a material (e.g. core-shell). SAXS is a non-destructive method that needs only very small amounts of sample which can be fully recovered after the measurements. SAXS has proven to be a powerful tool to the scientific community, especially related to the field of soft matter research. (1)

Generally, SAXS measurements are performed with a dedicated SAXS instrument. These advanced analytical instruments are composed of many complex components, such as a microfocus or metal jet X-ray source, optics to shape the beam, an evacuated beam path and dedicated sample environments, and a movable detector to access very low 2θ angles. This whole combination allows the measurement of samples with particle sizes ranging from a few nanometers up to a few micrometers. For example, Anton Paar’s laboratory beamline SAXSpoint 5.0 can routinely access particle diameters up to 310 nm (620 nm Bragg spacing), or even up to 2.4 μm (4.8 µm Bragg spacing) with an ultra-small-angle X-ray scattering (USAXS) module. The resolution in SAXS is defined as the maximum particle size that can be studied or the lowest accessible q value (q_min). (2)

References:
1. Schnabelegger H. et al.; “The SAXS Guide”; Anton Paar GmbH 2023
2. Glatter O. et al.; “Scattering methods and their application in colloid and interface science”; Elsevier 2018; ISBN: 978-0-12-813580-8