Improved small-angle x-ray scattering of nanoparticle self-assembly using a cell with a flat liquid surface

One important way of forming nanostructures entails the assembly of nanoparticle (NP) monolayers at a liquid surface. Probing this assembly of 11.8-nm-diameter iron oxide NPs by small-angle x-ray scattering (SAXS) is studied using cells with walls at angles designed to significantly reduce the size of the meniscus. This enables the collection of much larger signals in the SAXS images of ordered arrays of NPs at liquid/gas interfaces, as is needed for kinetics studies and x-ray exposure minimization, along with the observation of extremely high degrees of order. Meniscus flattening and improved signal collection are demonstrated for the assembly of ordered arrays of iron oxide NP monolayers at a diethylene glycol surface.