Recent advances in instrumentation for absolute emission quantum yield measurements

Abstract

The fluorescence and phosphorescence quantum yields ( Φ) of standard solutions have been re-evaluated based on an absolute method using an integrating sphere equipped with a multichannel spectrometer. We have examined in detail the Φ value of ruthenium(II) tris(2,2′-bipyridine) complex which have been often used as the standards in the determination of quantum yields of transition-metal complexes. This revealed that the Φ values for [Ru(bpy) 3] 2+ were 0.063 in deaerated H 2O, 0.040 in aerated H 2O, 0.095 in deaerated CH 3CN, and 0.018 in aerated CH 3CN, respectively, which are significantly higher than the previously accepted values. We have also examined the technical aspects in the determination of absolute emission quantum yields for lanthanide complexes and those of organic crystals of anthracene. For the accurate determination for lanthanide complexes, special care must be taken in the spectroscopic measurements because of their narrow absorption and emission bands. For organic crystals, the fluorescence quantum yields are reduced due to reabsorption, chemical impurities and structural defects. Our observations for highly purified anthracene crystals revealed that the lower limit value of Φ was 0.64.