XPS at solid–solution interface: experimental approaches

XPS is a very useful technique to study physicochemical phenomena at the solid–solution interface. It is essential that the interface remains unaltered during sample preparation and analysis. Experimental approaches dealing with this problem are reviewed and discussed. They include differential pumping, controlled adsorption/condensation from gas phase, fast freezing, and freeze‐drying. A recently developed fast‐freezing procedure of wet pastes that are obtained from powder suspensions by centrifuging is described. This method allows for estimating surface point‐of‐zero charge, thickness, and potential of electrical double layer from XPS data. New experimental findings on mineral–solution interfaces are presented.