Hard X-ray nanotomography of colloidal suspensions*

Colloidal suspensions are complex fluids that include colloidal nanoparticles or microparticles suspended in a liquid medium. In-situ characterizations of colloidal suspensions are necessary in many topics: for instance, wetting properties for colloidal particles on a fluid-fluid interface are essential but hard to be directly taken with conventional imaging techniques. Here we show that hard X-ray nanotomography clearly visualizes individual colloidal particles inside fluids in three dimensions (3D). In particularly, we demonstrate 3D images for colloidal particles adsorbed on water-oil emulsions: contact angle and configuration of colloids could be measured. We believe that hard X-ray nanotomography would be a powerful tool to identify the nature of colloidal particles inside or on fluids.