MEASUREMENT OF THERMAL-ENERGY RECOVERY USING THERMAL LENS SPECTROMETRY IN FLUORESCENCE QUENCHING EXPERIMENTS

This paper describes some limitations of the pulsed-laser thermal lens method in measuring the heat produced by non-radiative relaxation of excited fluorescent molecules. Simultaneous measurements of the fluore scence intensity and thermal lens signal have been carried out for flu orescein dianion in water and perylene in ethanol. It is shown that co mplete fluorescence quenching of fluorescein and perylene by potassium iodide and nitromethane, respectively, does not result in full recove ry of the thermal energy. The results depend on either the operating m ode of the excitation laser or the solvent composition.