Observation of water droplet on various materials by non-contacting AFM

The small water droplets which adhere to the material surface cause corrosion and photo catalytic reaction. It is important to study the behavior of these small water droplets to understand the mechanism of these reactions. Recently the author has succeeded in observing the droplet of pure mater on graphite by a non-contacting AC AFM mode. In this paper, the behavior of mater droplets was studied by combining the contact and non-contact scanning modes on graphite, mica and SUS304 stainless steel. The behavior of water droplets was dependent on the material and the solution and the water droplets were easily moved by contact mode scanning. Small water droplets were generated at the step site on the graphite surface, while only water films evolved on the mica surface at the humidity of 90%.