INVESTIGADORES
LAGORIO MarÍa Gabriela
artículos
Título:
Photophysics on Surfaces: Determination of Absolute Fluorescence Quantum Yields from Reflectance Spectra
Autor/es:
MARTÍN MIRENDA, M. GABRIELA LAGORIO AND ENRIQUE SAN ROMÁN
Revista:
LANGMUIR
Editorial:
American Chemical Society
Referencias:
Lugar: Washington; Año: 2004 p. 3690 - 3697
ISSN:
0743-7463
Resumen:
A method for the calculation of absolute fluorescence quantum yields for dyes attached to solid particles
based on reflectance measurements is reported. The same procedure allows calculation of true reflectance
spectra (free of fluorescence) for highly fluorescent materials as well. Samples of cresyl violet were immobilized
by adsorption on microgranular cellulose in the concentration range 4.5 10-9 to 3.8 10-6 mol g-1.
Diffuse and total reflectance spectra were recorded with and without insertion of an optical absorption
filter between the output of the integrating sphere of a reflectance spectrometer and the photodetector in
order to block fluorescence partially. From these data, the relative emission spectrum of the dye, the filter
transmission spectrum, and the detector sensitivity, true reflectances and absolute fluorescence quantum
yields were recovered. Observed fluorescence quantum yields, affected by dye aggregation and inner filter
effects, were concentration and wavelength dependent, ranging approximately between 0.1 and 0.6. The
analysis of remission function spectra showed that dye aggregation is negligible up to a concentration of
1.41 10-7 mol g-1. Fluorescence data were corrected for reemission and reabsorption using a suitable
model [Lagorio, M. G.; Dicelio, L. E.; Litter, M. I.; San Roma´n, E. J. Chem. Soc., Faraday Trans. 1998,
10-9 to 3.8 10-6 mol g-1.
Diffuse and total reflectance spectra were recorded with and without insertion of an optical absorption
filter between the output of the integrating sphere of a reflectance spectrometer and the photodetector in
order to block fluorescence partially. From these data, the relative emission spectrum of the dye, the filter
transmission spectrum, and the detector sensitivity, true reflectances and absolute fluorescence quantum
yields were recovered. Observed fluorescence quantum yields, affected by dye aggregation and inner filter
effects, were concentration and wavelength dependent, ranging approximately between 0.1 and 0.6. The
analysis of remission function spectra showed that dye aggregation is negligible up to a concentration of
1.41 10-7 mol g-1. Fluorescence data were corrected for reemission and reabsorption using a suitable
model [Lagorio, M. G.; Dicelio, L. E.; Litter, M. I.; San Roma´n, E. J. Chem. Soc., Faraday Trans. 1998,
10-7 mol g-1. Fluorescence data were corrected for reemission and reabsorption using a suitable
model [Lagorio, M. G.; Dicelio, L. E.; Litter, M. I.; San Roma´n, E. J. Chem. Soc., Faraday Trans. 1998,J. Chem. Soc., Faraday Trans. 1998,
94, 419]. Application of this model to samples showing no aggregation yielded a wavelength-independent
true fluorescence quantum yield of 0.60 ( 0.05, similar to values found in solution. The usage of cresyl
violet as a reference for the evaluation of fluorescence quantum yields for weakly fluorescing samples in
the solid phase is discussed.
, 419]. Application of this model to samples showing no aggregation yielded a wavelength-independent
true fluorescence quantum yield of 0.60 ( 0.05, similar to values found in solution. The usage of cresyl
violet as a reference for the evaluation of fluorescence quantum yields for weakly fluorescing samples in
the solid phase is discussed.
( 0.05, similar to values found in solution. The usage of cresyl
violet as a reference for the evaluation of fluorescence quantum yields for weakly fluorescing samples in
the solid phase is discussed.