Absolute fluorescence quantum yields by relative fluorescence and photoacoustic measurements of low level luminescence quenching

A method is reported which allows absolute fluorescence quantum yields Φ_F to be obtained from relative fluorescence and non-radiative emission (photoacoustic) data. Absolute calibration procedures, external standards, and total fluorescence quenching are eliminated through use of low concentrations of a heavy atom quencher. The relative decrease in fluorescence emission and increase in non-radiative emission as a function of the quencher concentration are related to Φ_F through a set of simultaneous equations. Fluorescence quantum yields of Φ_F = 0.59 ± 0.03 for cresyl violet perchlorate in EtOH and Φ_F = 0.55 ± 0.02 for quinine sulfate in 0.1 N H₂SO₄ are reported.