الفهرس 
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Abstract
The complexation of metallic silver nanoparticles (NPs) with fluorescein derivative laser dyes (p-aminophenol fluorescein, p-anisidine fluorescein and p-methyl aniline fluorescein ) have significant effect on optical properties of the laser dye, the fluorescence intensity, lifetime, photostability and the fluorescence efficiency. Which the [Ag : dye] complex has energy transfer effect from scattering energy of metallic Ag NPs to laser dyes spectra depending on the distance between them. This arises from interactions with surface plasmons resonance (SPR) in the metal nanoparticles. The size of prepared Ag NPs was determined expermentally by TEM and UV-Vis absorption spectroscopy techniques. Mie theory was also used to confirm the size of Ag NPs theoretically. Enhancement as well as quenching of fluorescence intensity has been observed and studied . It was found that fluorescence intensity can be tuned by adding various amounts of silver nanoparticles to the three dyes, when metal nanoparticles are located at certain distance (preferable for MEF phenomena), enhancement in fluorescence is observed. This effect has been explained by coupling of surface plasmon resonance from metal nanoparticles with fluorophore, resulting in the increase of excitation and emission rate of the fluorophore in the localized electromagnetic field. Emission enhancement factors were calculated for all samples. Different samples of different concentrations of the laser dyes (1×10-5 M, 5×10-5 M, 1×10-4 M) with different ranges of Ag NPs concentrations were prepared. Optical properties such as absorption data, emission data and fluorescence lifetime of all samples were determined and tabulated. Also some important photo-physical parameters such as extinction coefficient (ε), the absorption (σa) and the emission (σe) cross-sections, fluorescence quantum yield (фf) , oscillator strength( f), the dipole moment (μ), radiative decay rate constant (kr), energy yield of fluorescence (Ef) and the attenuation length Λ(λ) were assessed by using the absorption and emission spectra. Fluorescence enhancement efficiencies depended on the input pumping power of 450 nm blue diode laser were reported for the dyes without and with their optimum concentrations of Ag NPs that give the maximum enhancement fluorescence. Also the photostability of 1×10-5 M of the three dyes without and with optimum concentration of Ag NPs was measured by 450 nm blue diode laser. It noticed that, Gradual decrease in the output energy occurred with a fast rate in case of dyes with Ag NPs than this of pure dyes.