Photochemical Reactions connected with the Quenching of Fluorescence of Dyestuffs by Ferrous Ions in Solution

Abstract

IT has been found recently that ferrous ions exert a strong quenching effect on different fluorescent dyestuffs in solution¹. According to previous theoretical discussions², in the elementary process of quenching, the light quantum (h), is transferred from the excited dyestuff molecule (D_sh) to the Fe⁺⁺ ion by a collision of the second kind. Unlike the case of direct irradiation, when the Franck-Condon principle is observed, we can gain here some energy from the potential energy of the heavy particles. Thus in this case the hydration energy of the ions formed in the process and the binding energy between dyestuff and H-atom can be used according to: