Monitoring nanoparticle growth in a microreactor by combined micro-SAXS and micro-Raman techniques

M. Reynolds, E. Di Cola, M. Sztucki, A. Gourrier, C. Montero, M. Burghammer
European Synchrotron Radiation Facility, FR

Keywords: nanoparticle, surface plasmon resonance, microSAXS, microRaman, SERS


Noble metal nanoparticles have been extensively exploited in recent decades for their importance in fundamental science and their applications in biomedical therapeutics, catalysis and as a bottom-up approach to the production of ordered nanostructures. Key to their physicochemical properties is the size and surface functionality dependent surface plasmon band which propagates at the nanoparticle surface. In order to monitor the development of the surface plasmon band in situ during nanoparticle synthesis, we have optimized the combined microSAXS/microRaman setup of the Microfocus Beamline (ID13, ESRF, Grenoble, France) to incorporate a microfluidics environment. The incident X-rays and Raman laser are co-focalized onto the same point in the custom made microreactor. This means nanoparticle size and size distribution, ligand binding, and surface plasmon band evolution can be monitored simultaneously at different stages of the reaction. As a model system, we have investigated silver nanoparticle synthesis and surface functionalization with cysteamine. It was found that particles with a core radius ~0.7 nm or larger exhibited metallic character. Furthermore, as nanoparticle size increases, more electron density is transferred from the bound ligand to the particle surface. Details of the experimental setup will also be presented.