Measurement of the absolute fluorescence quantum yield of rhodamine B solution using a dual-beam thermal lens technique

Abstract

The dual-beam thermal lens technique has been found to be very\neffective for the measurement of fluorescence quantum yields of dye solutions. The\nconcentration-dependence of the quantum yield of rhodamine B in methanol is\nstudied here using this technique. The observed results are in line with the\nconclusion that the reduction in the quantum yield in the quenching region is\nessentially due to the non-radiative relaxation of the absorbed energy. The thermal\nlens has been found to become abberated above 40 mW of pump laser power.\nThis low value for the upper limit of pump power is due to the fact that the medium\nis a resonantly absorbing one.