Saturation of the fluorescence of dye solutions exposed to pulsed laser excitation

The fluorescence saturation curves of dye molecules were calculated for optically thin layers of solutions exposed to pulsed laser excitation. Intercombination conversion of molecules from an excited singlet state to a triplet state was taken into account for various distributions of the photon flux density of the exciting radiation as a function of time and in the beam cross section. Good agreement was obtained between the calculated results and the experimental saturation curves of aqueous solutions of three dyes exhibiting substantially different quantum efficiencies of conversion to the triplet state.