Recent times have seen an increase in the development of fluorescent and phosphorescent materials for applications including LED lamps and EL. We have reported on the development of a quantum efficiency measurement system for powder samples [1]. The main issue has been to measure quantum efficiency to evaluate it for solution samples. In this study, we have developed measurement process for quantum efficiency using integrating hemisphere system with eliminating the problem of 2nd order fluorescence, which is called "Re-excitation". We have used our system to perform measurements on Fluorescein (C20H12O5, MW: 332.306) and Quinine Sulfate, dihydrate (C20H24N2O2, MW: 782.96) and some other materials as standard samples. The results, which we report here, correspond to the literature values [2-5].

Keywords: LED; Phosphor; Quantum efficiency; Integrating sphere; Integrating hemisphere