Probing liquid ∣ liquid interfaces using neutron reflection measurements and scanning electrochemical microscopy

A new experimental approach to neutron reflectivity experiments at liquid ∣ liquid interfaces is presented. This approach allows the investigation of the interface between two immiscible electrolyte solutions. The experimental design involves establishing a thin (sub–10 μm) aqueous layer on a single crystal quartz block which is then positioned over a PTFE trough containing the organic phase. The dimensions of the thin aqueous film, necessary for the neutron studies, have been characterised using scanning electrochemical microscopy (SECM) double potential step chronoamperometry measurements. Initial results of neutron reflection at the 1,2-dichloroethane ∣ aqueous potassium hydroxide interface show a smooth interface with a root mean square roughness less than 10 Å, in agreement with theoretical predictions.