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Frequency-Domain Measurement of the Photodegradation Process of Fluorescein



Adolfas K. Gaigalas, Lili Wang, R F. Vogt


The frequency domain technique is applied to measure the photodegrdation rate offluorescein in aqueous solutions. The illuminating light is modulated and the changes in fluorescence from the illuminated region are detected synchronously. A constant flow rate is imposed on the fluorescein solution to control the mass transport of fluorescein into the illuminated region. The fluorescence response is describe by a model which assumes that the photodegradation occurs from the triplet excited state. The predictions of the model are consistent with the observed variations of the fluorescence response with flow rate, modulation frequency, and incident power. We discuss how the dependence of the model parameters on experimental conditions can be used to infer the apparent photodegradation rate as well as some of the details of the photodegrdation mechanism. The results are consistent with the known mechanism of photodegradation of fluorescein.
Photochemistry and Photobiology
No. 1


fluorescein, impedance, mechanism, photodegradation


Gaigalas, A. , Wang, L. and Vogt, R. (2002), Frequency-Domain Measurement of the Photodegradation Process of Fluorescein, Photochemistry and Photobiology (Accessed April 19, 2024)
Created July 1, 2002, Updated February 17, 2017