Thermal lens probing of distant dependent fluorescence quenching of Rhodamine 6G by silver nanoparticles

Manipulation of the characteristics of laser dyes using metal nanoparticles is one of the rapidly growing areas in nanotechnology due to their promising applications in diverse fields, ranging from biomedical imaging to green energy. The energy transfer behavior of a silver nanoparticle (Ag NP) with a dye molecule, Rhodamine 6G (Rh 6G), is interrogated using static photoluminescence as well as a laser based dual beam thermal lens technique. Spherical Ag NPs of various concentrations are prepared using chemical reduction method and is mixed with a fixed concentration of Rh 6G. It is observed that the intrinsic fluorescence of Rh 6G (1×10^-6 M) is quenched in proximity of the Ag NPs and the quenching efficiency increases with an increase in Ag NP concentration (2.5×10^-4-10×10^-4 M). The dye-NP distance is evaluated by varying the concentrations of Ag NPs and it is found to decrease with an increase in the NP concentration in the mixture from 92 to 69 Å (1 Å=10^-10 m). The distance dependent energy transfer efficiency showed that dye-NP mixture follows R^-4 dependence, where R is the dye-NP distance.