We demonstrate a high resolution in situ experimental method for performing simultaneous size-classification and characterization of functional nanoscale gold clusters (NGCs) based on asymmetric-flow field flow fractionation (AFFF). Field emission scanning electron microscopy, atomic force microscopy, multi-angle light scattering (MALS), and in situ ultraviolet-visible optical spectroscopy provide complementary data and imagery confirming the cluster state (i.e., dimer, trimer, tetramer), packing structure, and purity of fractionated populations. An orthogonal analysis of NGC size distributions is obtained using an electrospray-differential mobility analyzer (ES-DMA). A linear correlation exists between the normalized MALS intensity (measured during AFFF elution) and the corresponding number concentration (measured by ES-DMA), establishing the capacity for AFFF to quantify the absolute number concentration of NGCs. The results and corresponding methodology summarized here provide proof of concept for general applications involving the formation, isolation and in situ analysis of both functional and adventitious nanoparticle clusters of finite size.
Citation: Journal of the American Chemical Society
Pub Type: Journals
field flow fractionation, electrospray, differential mobility analyzer, microscopy, gold, nanoparticle, aggregate, cluster, spectroscopy.