Influence of silver nanoparticles on the spectral-luminescent and lasing properties of merocyanine dyes solutions

The effect of silver nanoparticles (NPs) on spectral-luminescent and generation properties of ethanol solutions of vinylogous series neutral merocyanine dye has been studied. Adding silver NPs to dye solutions has led to a growth of optical density D and fluorescence intensity I (FL) of the dye molecules. With lengthening of a polymethine chain the silver NPs' effect on the D and I (IFL) values has been increasing. Whilst, a spectral overlap between the silver NPs and merocyanines has been decreasing. It is argued that the effect of the silver NPs on optical properties of the dye solutions may be related to the growth in the value of electron dipole moment of ground-to-the first excited state transition at the lengthened polymethine chain. The dye fluorescence quantum yields and lifetimes in the presence of silver NPs have been measured. Adding the silver NPs to the merocyanine ethanol solutions has led to the reduced dye stimulated emission generation threshold (P (TR)). A decrease in the value P (TR) corresponds to the changes observed for the D, I (FL) values and dye luminescence quantum yields.