Abstract
Previous X-ray scattering measurements demonstrated the formation of a voltage-tunable 2-dimensional lattice of nanoparticles situated at the liquid-liquid interface between two immiscible electrolyte solutions (Nano Letters 2014, 14, 6816−6822). The nanoparticles had Au cores coated with trimethylammonium terminated ligands and the ITIES consisted of NaCl in water and BTPPATPFB in 1,2-dichloroethane. Here, we present additional measurements on this system which illustrate a transition that occurs at more negative potentials. The transition represents a breakup of the 2D monolayer lattice into a disordered sub-monolayer of nanoparticles that coexists with small nanoparticle clusters in the vicinity of the interface. Grazing Incidence Small Angle X-ray Scattering (GISAXS) provides evidence for the breakup of the lattice and the appearance of clusters. X-ray reflectivity (XR) characterizes the relative location along the interfacial normal of the different types of nanoparticle assemblies.