9362206 Small Fluorescence methods are used throughout a variety of fields including biotechnology, microscopy, immunology, biology, chemistry, photochemistry and photophysics. Many fluorescence techniques employ changes in fluorescence intensity of chromophores in response to their molecular environment. Their goal is to correlate fluorescence intensity (an arbitrary value) with fluorescence quantum yield (a fundamental photophysical parameter, but one that is difficult to measure). Our objective is to determine the feasibility of using a pulsed-laser photoacoustic method combined with fluorescence detection to accurately determine fluorescence quantum yields. Such a determination should be possible with relatively inexpensive instrumentation, and sufficient automation to make quantum yield determinations rapid and easy to perform. In our instrument a pulsed-laser beam excites a solution of molecules, a light detector measures fluorescence, and a piezoelectric transducer is used to determine the amplitude of a compressive sound wave resulting from heat deposited in the solution. Yields of triplet states will be distinguished because such states are long lived. To support the automation of this technique, methods are proposed for determining the average emitted photon energy without resorting to a complete fluorescence spectral measurement. ***
