A Quantitative Theory Model of a Photobleaching Mechanism

A photobleaching model; D-P (dye-photon interaction) and D-O (Dye-oxygen oxidative reaction) photobleaching theory, is proposed. The quantitative power dependences of photobleaching rates with both one- and two-photon excitations (1 PE and TPE) are obtained. This photobleaching model can be used to elucidate commendably our and other experimental results. Experimental studies of the photobleaching rates for rhodamine B with TPE under unsaturation conditions reveals that the power dependences of photobleaching rates increase with the increasing dye concentration, and that the photobleaching rate of single molecule increases in the second power of the excitation intensity, which is different from the high-order (> 3) nonlinear dependence of ensemble molecules.