Photophysical and photochemical properties of rhodamine 6G in alcoholic and aqueous sodium dodecylsulphate micellar solutions
ABSTRACT The photodecomposition of the rhodamine 6G (R6G) dye dissolved in n-alcohols and aqueous sodium dodecylsulphate (SDS) micellar solution was investigated under continuous UV-visible illumination. The results indicate that in alcohol solution the photodecomposition efficiency increases with the dye concentration. It also depends on the nature of the alcohol the lowest efficiency being observed in ethyleneglycol. The mechanism involves the electron transfer reaction of the triplet excited state with a ground state dye molecule (T + S0 → R+ + R−. In aqueous SDS micellar solution, the R6G cation is embedded in the hydrophobic interior of the micelle close to the negatively charged sulphate end groups. We show that a rather high concentration (3 × 10−3 M) of R6G can be dissolved in 10−1 M SDS aqueous solution, protecting R6G from the electron transfer reaction and secondary decomposition reactions.
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ABSTRACT: Sorption of laser dye rhodamine 6G in perfluorosulphonate cation-exchange membrane (Nafion) from aqueous solution has been investigated by optical absorption and emission studies. In the H+ form, the optical absorption spectra changes with water content in the membrane and is attributed to the change in H+ ion concentration in dry and wet (with water) conditions of the membrane. The dye is present in the protonated form in the dry membrane and in the cationic form in the wet membrane. In the Na+ form, rhodamine 6G is present in the cationic form and the optical absorption spectra do not show changes in dry and water-wet conditions of the membrane. The fluorescence lifetime of rhodamine 6G is 3.97 ns and decay is single exponential. In the Na+ and H+ forms of the membrane, the fluorescence decay is biexponential. The lifetime and the relative ratio vary for the Na+ and H+ forms and also with the water content in the membrane. Owing to the large size of the dye low values for the diffusion coefficient are observed (3.2 × 10–11 and 2.0 × 10–8 cm2 s–1 for Na+ and H+ form of Nafion, respectively). As compared to aqueous solutions, rhodamine 6G in Nafion membrane is observed to be photostable.Journal of the Chemical Society Faraday Transactions 01/1992; 88(1). DOI:10.1039/ft9928800041 · 4.20 Impact Factor