Investigations of prussian blue films using surface plasmon resonance

A fiber-optic based surface plasmon resonance (SPR) instrument is used to characterize electrodeposited prussian blue (PB) films. PB films are deposited potentiostatically or galvanostatically onto the gold sensing surface. When reduced to prussian white (PW), the film undergoes a reversible refractive index change that is observed using SPR. The strong absorbance of PB films within the sensing region of the instrument inhibits quantitative characterization of these films; however qualitative characterization has been achieved. The PB coated SPR probe can be used as an optical transducer of electrochemical phenomena. A PB film is deposited on the gold SPR sensing surface; the probe is submerged in 0.1 M KNO3 in a tube terminated with a porous vycor frit. The isolated PB half-cell and a AgCl-coated Ag wire are placed in a beaker containing 0.1 M KNO3 and connected by a variable battery. Addition of chloride to the bulk solution changes the potential of the AgCl wire, which induces a change in the PB film that can be observed using SPR. A change in chloride concentration of 40 muM can be detected using this system. (C) 2001 Elsevier Science B.V. All rights reserved.