Determination of the absolute fluorescence quantum yield of rhodamine 6G with optical and photoacoustic methods--providing the basis for fluorescence quantum yield standards.

To establish the methodical basis for the development and certification of fluorescence quantum yield standards, we determined the fluorescence quantum yield Φ(f) of rhodamine 6G (R6G) with two absolute methods with complementary measurement principles, here optical spectroscopy using an integrating sphere setup and pulsed laser photoacoustic spectroscopy (PAS). For the assessment of aggregation- and reabsorption-induced distortions of measured fluorescence quantum yields and procedures for the reliable consideration of such effects, this systematic comparison was performed in ethanol and in water employing different concentrations of R6G. In addition, the relative and absolute fluorescence quantum yields of these solutions were obtained with a calibrated spectrofluorometer and a commercialized integrating sphere setup. Based upon this systematic comparison, experimental advantages and systematic sources of variation were identified for both methods.