Photoreduction of methylene blue on cadmium sulfide powder

The relaxation of photogenerated charge carriers in cadmium sulfide powder and the reduction of surface bound methylene blue have been investigated us ing both picosecond multiple light scattering transients and transient band gap emission measurements. A comparison of the bleaching kinetics for adso rbed dye with near-Ii absorption and band gap emission transients from the semiconductor indicate that interfacial electron transfer is driven by mobi le conduction band carriers with little participation by the longer-lived w eakly trapped carriers. In addition, adsorbate reduction is simulated using the diffusion equation with a surface reaction. (C) 2000 Elsevier Science B.V. All rights reserved.