PHOTOVOLTAIC DETECTION METHOD FOR CONDENSED-PHASE PHOTOIONIZATION

A novel method is examined for the detection of photoinduced ions in the absence of an applied electric field. The analyte solution is enclosed between two optically transparent electrodes and is irradiated transversely by a pulsed laser. After irradiation, the extent of photoionization differs at the two electrodes and a transient photopotential is developed. This photovoltaic response is characterized with respect to electrode composition and film thickness, electrode separation distance, illuminated area, and laser pulse energy. In addition, the dependence of the photopotential on solute concentration is examined in a variety of polar solvents. Detection limits of 5 X 10(-7) M potassium permanganate in water are reported, with a linear range exceeding 3 orders of magnitude.