Abstract
Spatial and temporal structure of electric double layer (EDL) in the vicinity of a glass wall of microchannel has been investigated by a novel nanoscale optical measurement technique using large-area evanescent wave light illumination and fluorescent dye. The fluorescent dye near the glass surface was excited by the evanescent wave, which was generated at an electrolyte-glass interface by total internal reflection of a laser beam with the characteristic penetration depth of 88 nm. As the concentration of fluorescent dye in the vicinity of the glass surface is dependent on the EDL thickness, calibration curves depicting the relationship between the fluorescent intensity and the EDL thickness were prepared to obtain the spatial and temporal distribution of EDL. It is concluded that the spatial distribution of EDL thickness is dependent on the molecular diffusion of positive ion in a buffer solution in the vicinity of the wall surface.
