Lifetime Measurements Using Fluorescence Emission.

Two experimental methods are developed for measuring fluorescence lifetimes on the order of ten nanoseconds. These data are necessary for measurements of species concentrations in combustion flames. The first method is based on counting photons within a fixed time interval, the position of which can be varied with respect to the excitation time of the sample. The second method uses a time to pulse height converter to measure the elapsed time between excitation of the sample and emission of a photon. The number of photons detected per laser pulse is reduced to one or less in order to obtain a valid statistical distribution. A tunable dye laser is used as the excitation source, and nitrogen dioxide is used as the test sample at pressures of 30 torr or less. Author