Experimental set-up for time resolved small angle X-ray scattering studies of nanoparticles formation using a free-jet micromixer

Abstract: Recently, we have designed, fabricated and tested a free-jet micromixer for time resolved small angle X-ray scattering (SAXS) studies of nanoparticles formation in the <100μs time range. The microjet has a diameter of 25μm and a time of first accessible measurement of 75μs has been obtained. This result can still be improved. In this communication, we present a method to estimate whether a given chemical or biological reaction can be investigated with the micromixer, and to optimize the beam size for the measurement at the chosen SAXS beamline. Moreover, we describe a system based on stereoscopic imaging which allows the alignment of the jet with the X-ray beam with a precision of 20μm. The proposed experimental procedures have been successfully employed to observe the formation of calcium carbonate (CaCO3) nanoparticles from the reaction of sodium carbonate (Na2CO3) and calcium chloride (CaCl2). The induction time has been estimated in the order of 200μs and the determined radius of the particles is about 14nm. [Copyright &y& Elsevier]