INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
Trapping of Rhodamine 6G excitation energy on cellulose microparticles
SERGIO G. LÓPEZ; GREGOR WORRINGER; HERNÁN B. RODRÍGUEZ; ENRIQUE SAN ROMÁN
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
ROYAL SOC CHEMISTRY
Año: 2010 vol. 12 p. 2246 - 2246
Rhodamine 6G (R6G) was adsorbed on cellulose microparticles and fluorescence quantum yields and decays were measured as a function of dye loading. Though no spectroscopic evidence of dye aggregation was found, a noticeable decrease of quantum yieldafter correction for reabsorption and reemission of fluorescenceand shortening of decays were observed at the highest loadings. These effects were attributed to the dissipation of the excitation energy by traps constituted by R6G pairs, leading to static and dynamic quenching produced by direct absorption of traps and non-radiative energy transfer from monomers, respectively. Regarding the nature of traps, two extreme approaches were considered: (a) equilibrium between monomers slightly interacting in the ground state and (b) randomly distributed monomers located below a critical distance (statistical traps). Both approaches accounted quantitatively for the observed facts. The effect of energy migration was evaluated through computational simulations. As the concentration of traps could only be indirectly inferred, in some experiments an external energy transfer quencher, Methylene Blue, was coadsorbed and the results were compared with those obtained with pure R6G.