PHOTOCHEMISTRY OF SEMICONDUCTOR PARTICLES .2. ADSORPTION OF IONS ON ZNS COLLOID AND QUENCHING OF FLUORESCENCE

Various ions were used to study the adsorption on the ZnS particle and the quenching of fluorescence. Three kinds of adsorption process were found for these ions. The mechanism of the fluorescence quenching depends on the nature of the adsorption process. A nearly dynamic quenching was found for MV2+ ions, whereas quenching by Cd2+ ions was mainly through the static process. The quenching efficiency is determined by the chemical properties of the ion, such as the adsorbability and redox potential. Of all the ions used, the Cd2+ and MV2+ ions are the most effective quenchers. It has also been found that the quenching depends strongly upon the surface condition, which determines the distribution of the photogenerated charge carriers in the ZnS particle.