Absolute determination of the quantum efficiency of an organic wavelength shifter by a temporal measurement

A novel technique for measuring organic fluor quantum efficiency has been developed. The measurement involves evaluating the change in the luminescence temporal distribution as a function of solute concentration. The solute was excited by the deep UV emissions of BaF ₂ and luminescence time spectra were measured by a time-correlated single photon counting technique. As the solute concentration is increased, the luminescence spectra have a decreased contribution from transmitted UV light and an increased contribution from solute fluorescence. The quantum efficiency of the solute is determined using these data along with a correction for the differences in the detection efficiency of the primary and secondary light. The correction was determined by an optical transport code, DETECT, and the measured photomultiplier tube spectral response. Using this technique, the quantum efficiency of 9,10 diphenylanthracene in cyclohexane was calculated to be 0.76