Quantum efficiency of laser dyes in aerogels

Abstract

Aerogels are highly porous materials that can be made with pores that have characteristic dimensions as small as 10 nm. A laser dye solution absorbed into small pores of an aerogel serve as a good example of a quantum confined molecular system. In this research two representative laser dyes, Rhodamine 6G and Rhodamine B, were chosen and their fluorescence quantum efficiency values were investigated when solutions of these dyes were absorbed in silica aerogels. Significant increases in the quantum efficiency values were observed for the dye solutions in the aerogels as compared to the bulk solutions (0.89 to 0.99 for Rh6G and 0.37 to 0.77 for RhB). The increase in the radiative quantum efficiency indicates a decrease in the rate constants of non-radiative processes taking place between different energy levels of the dye molecules when they are confined into silica pores. This change can be attributed to an interaction between the dye molecules and the surface of the pores.