SPECTROSCOPIC AND ELECTROCHEMICAL ANALYSES OF ELECTRON-TRANSFER AND MASS-TRANSFER ACROSS THE MICRODROPLET SOLUTION INTERFACE

A laser trapping - spectroscopy - electrochemistry method has been app lied to study electron transfer and mass transfer across the microdrop let/water interface. Electron transfer from Fe(III) produced electroch emically at an optically transparent SnO2 electrode in water to ferroc ene (FeCp) in an oil droplet was directly measured by both fluorometri c and coulometric methods. The rate determining step of the FeCp oxida tion was the electron transfer process across the droplet/water interf ace and the relevant rate constant was determined for individual micro meter droplets. As a model of color developing reactions in photograph ic emulsions, cyan dye formation reaction in a single oil droplet was also investigated. Mass transfer of a reagent across the droplet/water interface and subsequent dye formation reaction in the droplet were d emonstrated. The yield and the rate constant of the dye formation reac tion in single droplets were also discussed.