Colloidal cdS fluorescence quenching by MV2+ under continuous irradiation.

This paper describes the photochemical behavior of the colloidal CdS/MV2+/COP system in excess of Na2S. We determined the rate constants for all the reactions which take place in solution under continuos irradiation and put into evidence the following intermediates: the monomer radical MVradical+ which dimerizes in (MVradical+)2 radical and the double reduced form MV0 of methylviologen. By this continuos irradiation technique we showed that the same reactions which take place on CdS particle surface with ultra fast rates can undergo also in bulk, but with a much slower rates.