The extension of the application of SAXS in the study of POMs: scattering functions of carved-ellipsoid-shaped particles

With the emergence of more and more nano-scaled molecular clusters, small angle X-ray scattering (SAXS) has been widely used to characterize their structures and morphologies. However, the existing scattering models encounter difficulties when it comes to wheel-shaped particles with crescent cross-sections, like a group of polyoxometalates (POMs) named molybdenum blue. Therefore, to fit with their scattering data, custom carved ellipsoid models are built and the scattering functions are derived in ellipsoidal coordinates. 

  Fig. 1 Left, Graphical representation of POMs and torus model; Right, 3D representation of custom carved-ellipsoid model.

The theoretical scattering curves can be obtained by numerical integral. And the calculation can be accelerated using parallel computing. These models have been successfully applied to the fitting of experimental scattering curves of some molybdenum blue clusters. The fitting results of custom carved ellipsoid model are better than the torus model, which is the closest pre-existing model compared with the shape of molybdenum blue clusters.

Fig. 2 Fitting results of custom carved-ellipsoid model (blue) and torus model (green), with experimental solution scattering curves of molybdenum blue clusters (red).

This work has been recently published in Journal of Applied Crystallography as early view article. Mr. Mu Li is the first author and Prof. Dr. Panchao Yin is the corresponding author of this work. This work is supported by National Key Research and Development Program of China (No. 2018YFB0704200), the National Natural Science Foundation of China (No. 51873067) and the Fundamental Research Funds for the Central Universities (grant No. 2018JQ04). The synchrotron-based SAXS study was carried out at BL16B of the Shanghai Synchrotron Radiation Facility and 12-ID-B and C of the Advanced Photon Source. 

Li, M.; Yin, P., Scattering functions of carved-ellipsoid-shaped particles. J. Appl. Crystallogr. 2019, 52 (1), doi:10.1107/S1600576718016771.

Link：https://onlinelibrary.wiley.com/iucr/doi/10.1107/S1600576718016771

Source from South China Advanced Institute for Soft Matter Science and Technology