Abstract
The relationship between the OH^- concentration of mixing solution and the electrostatic potential at the liquid-liquid interface was investigated. Two kinds of fluorescent dye whose concentration changes depending on the electrostatic potential were introduced in the aqueous solution. An evanescent wave excited the fluorescent dye in the vicinity of the interface, and nano color imaging, which is based on nanoscale laser-induced fluorescence, was used to acquire the fluorescent intensity distribution. The OH^- concentration of the mixed solutions was formed to vary spatially, gradually reducing from the side of the higher pH solution to the lower pH solution. The result indicates that the electrostatic potential changes depending on the spatial OH^- concentration.
