Validation of fluorescence quantum yields for light-scattering powdered samples by laser-induced optoacoustic spectroscopy.

Determination of quantum yields for various processes (such as fluorescence and triplet formation) in dye-loaded light-scattering powdered samples is an open issue. Here, we report the testing of laser-induced optoacoustic spectroscopy (LIOAS) for the determination of fluorescence quantum yields of Rhodamine 101 and Rhodamine 6G adsorbed at various loadings on microgranular cellulose powder. The results of the LIOAS experiments are consistent with those from the method developed in one of our laboratories based on the measurement of apparent reflectance using an integrating sphere [Mirenda, M.; Lagorio, M. G.; San Roman, E. Langmuir 2004, 20, 3690-3697], which allows the simultaneous calculation of fluorescence quantum yield and reflectance devoid of fluorescence artifacts. Criteria to quantify overall errors and detect outlying values are developed. The theory underlying the application of LIOAS to light-scattering samples and experimental details are presented.