OBSERVATION OF ADSORBED WATER DROPLETS ON GOLD SURFACES

The research of adsorption water on metal surfaces has been conducted mainly with FT-IR and QCM (Quartz Crystal Micro-balance). Among these methods, QCM has the high reliability as a research technique of adsor ption water because of its relatively easy experiment. However, there has been no report on the direct observation of growth of water drople t or a water film on QCM surface. At present, therefore, it is difficu lt to understand the growth mechanism of water droplets or water film. In this study, the QCM measurement of adsorption water was carried ou t using a gold-coated quartz crystal. Moreover, for comparison with th e QCM results, the non-contact mode AFM measurement was made by using an environmental cell that can control the relative humidity, and the nucleation and disappearance of water droplets were directly observed. As the results, the change in weight as a function of relative humidi ty by the QCM measurement was small when the gold surface of QCM was c lean and few water droplets were present on the surface. It has been c onfirmed that the increase and decrease in weight depending on the rel ative humidity are due to the growth and shrink of adsorbed water drop lets.