Probing the absolute scattering intensity by means of a laboratory-based small-angle X-ray scattering camera using an imaging plate detector

Abstract

This paper deals with the application of an imaging plate (IP) detector for probing absolute intensities in small‐angle X‐ray scattering experiments. The IP detector is used with an in‐house modified Kratky camera. It is shown that the normalization of scattering data to the transmitted primary beam intensity properly compensates for various unwanted features typically associated with the IP detector, e.g. the fading effect and poorly reproducible scanning times, promoting precise absolute intensity calibration. The absolute intensity calibration was performed by measuring a large number of different silica sols serving as secondary standards. The calibration factor, which converts the measured data into absolute units, was determined by the average over the data obtained for different silica sols, providing a precise calibration of the IP detector. In particular, it is shown that silica sols do not require application of synchrotron radiation or a long exposure time as typically needed if pure liquids or standard proteins are used as secondary standards. To check the applicability of the IP detector in a real synthesis, Stöber silica particles were synthesized under various reaction conditions and the scattering intensity was probed and converted into absolute units. The volume fractions and the number densities of silica particles provided by the absolute intensities showed a good agreement with theoretical values predicted for the different reaction conditions. Therefore, the IP detector can be used for accurate probing of absolute intensities.

Characterisation of structured and functionalised particles by small-angle X-ray scattering (SAXS)

“…In some cases, the absolute scattering intensity is necessary for determination of particle number concentration and mean molecular weight. Calibration of absolute instensity can be done using standard calibrating materials such as, water, pure liquids, monodisperse colloidal suspensions and glassy carbon (Orthaber et al, 2000;Dreiss et al, 2006;Fan et al, 2010;Zhang et al, 2010;Gutsche et al, 2016). The use of absolute instensity has advantages like independence of measurement time, sample thickness and camera geometry.…”