INVESTIGADORES
BERTOLOTTI Sonia Graciela
artículos
Título:
Comparison of the Kinetics of Electron Transfer in the Diffusion Limit for the Singlet and Triplet Quenching of Eosin Y by Quinones
Autor/es:
BERTOLOTTI, SONIA G; MONTEJANO, HERNÁN A.; PREVITALI, CARLOS M.
Revista:
Photochemistry and Photobiology,
Editorial:
American Society of Photobiology
Referencias:
Año: 2013 vol. 19 p. 1442 - 1447
ISSN:
1751-1097
Resumen:
Electron transfer (ET) rate constants were determined by
means of lifetime measurements for the fluorescence quenching
and by laser flash photolysis for the triplet quenching of
the dye eosin Y by benzoquinones in acetonitrile. The results
represent a new aspect of the dependence of the rate constants
with the driving force in the diffusion limit region.
That is, the rate constants for singlet quenching in the highly
negative region of DGet do not decrease as predicted by Marcus
theory, but rather show a small positive dependence on
the driving force. However, it is found that, in the same free
energy range, the triplet rate constants are lower than those
for the singlet process. They also increase with the exergonicity
of the reaction, but the dependence with DGet is less
marked than that found for the singlet reaction. Even at a
Gibbs energy change of 1.0 eV the triplet quenching rate
constants do not reach the theoretical diffusion limit. The
results are analyzed using the current theories for diffusionmediated
ET reactions.