Effect of silver NPs plasmon on optical properties of fluorescein dye

In this work we studied the effect of silver nanoparticles “AgNPs” on the optical properties of fluoretain-->rescein dye. Fluorescein dye solutions have been mixed with different concentrations of colloidal AgNPs. Absorption and fluorescence enhancement of fluorescein dye molecules was detected in the presence of AgNPs. Fluorescence enhancement of the dye molecules was observed with a maximal enhancement factor of about 3-fold. Enhancement of the rate of radiative transition was also detected. The enhancement mechanisms are attributed to a modification of the local density of electromagnetic modes in the vicinity of AgNPs at energies resonant with surface Plasmon. The ability of fluorophore-metal mixture to actively enhance the dye's luminescence could leads to new opportunities for technological development of light emitting and photonic devices. It also may have applications in the fields of bio-technology and medical diagnostics as new class of fluorescence based sensing.