PHOTOINDUCED ELECTRON-TRANSFER IN MONOLAYERS AT THE MONOLAYER-WATER INTERFACE

We have investigated the photoinduced electron transfer from an excited donor (oxacyanine) incorporated in a matrix monolayer at the air-water interface to an acceptor (methyl viologen) adsorbed at the monolayer-water interface from the aqueous subphase. The steady state surface density and the kinetics of adsorption of the acceptor at the monolayer-water interface were measured using surface pressure, surface potential, surface reflection and fluorescence techniques. The acceptor adsorption was found to be largely governed by the interfacial potential. No evidence for acceptor penetration in the monolayer was found. Photoinduced electron transfer was studied by measuring the fluorescence intensity simultaneously with the surface pressure-area isotherms. Fluorescence intensity of the donor decreased by three orders of magnitude as a result of electron transfer using bulk acceptor concentration in the 10(-8)-10(-5) M range.