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Critical review of the determination of photoluminescence quantum yields of luminescent reporters

Würth, C., Geißler, D., Behnke, T., Kaiser, M., Resch-Genger, U.
Analytical and bioanalytical chemistry 2015 v.407 no.1 pp. 59-78
dyes, fluorescence, fluorescent proteins, nanocrystals, nanoparticles, photoluminescence, semiconductors, uncertainty, wavelengths
A crucial variable for methodical performance evaluation and comparison of luminescent reporters is the photoluminescence quantum yield (Φₚₗ). This quantity, defined as the number of emitted photons per number of absorbed photons, is the direct measure of the efficiency of the conversion of absorbed photons into emitted light for small organic dyes, fluorescent proteins, metal–ligand complexes, metal clusters, polymeric nanoparticles, and semiconductor and up-conversion nanocrystals. Φₚₗdetermines the sensitivity for the detection of a specific analyte from the chromophore perspective, together with its molar-absorption coefficient at the excitation wavelength. In this review we discuss different optical and photothermal methods for measuring Φₚₗof transparent and scattering systems for the most common classes of luminescent reporters, and critically evaluate their potential and limitations. In addition, reporter-specific effects and sources of uncertainty are addressed. The ultimate objective is to provide users of fluorescence techniques with validated tools for the determination of Φₚₗ, including a series of Φₚₗstandards for the ultraviolet, visible, and near-infrared regions, and to enable better judgment of the reliability of literature data.