LASER ELECTROCHEMICAL DETECTION TECHNIQUE IN A FLOW SYSTEM

A platinum electrode was illuminated with an intermittent Ar+ laser be am in a flowing solution from the front side of the electrode. The cur rent induced by this laser illumination was recorded as a function of electrode potential with a lock-in amplifier and was directly observed with an oscilloscope. Experimental results for the [Fe(CN)6]4-, [Fe(C N)6]3-, Fe2+ and Fe3+ solutions indicated that the laser heating of th e electrode promotes or depresses the electron transfer process, depen ding on the standard entropy change of the electrode reaction, promote s the mass transfer process and induces adsorption or desorption of an ions. Further, the induced current was proportional to the concentrati on and strongly depended on the chopping frequency and the flow rate. This laser electrochemical (LEC) detection can be used as a new electr ochemical detector in electroanalytical chemistry.