Presently, there are several techniques for measurement of fluorescence lifetimes of organic molecules. These techniques, reviewed by Ware,1can be divided into two basic groups, those based upon pulsed sources and those based on modulated sources and phase shift measurement. In the pulsed methods, repetitive, short pulse width, intense excitation pulses excite the fluorophor and the fluorescence decay is measured; the source temporal response must be deconvoluced from the fluorescence decay in order to evaluate the fluorescence signal and lifetime. Typical sources of excitation include nanosecond flashlamps and more recently nanosecond N2-laser (with or without a dye laser) and mode-locked lasers with picosecond pulse widths2-6. The modulated source phase shift methods,1involve sinusoidal excitation of the fluorophor and measurement of the phase shift between the modulated excitation source and the modulated flourescence. Because modulation frequencies are limited to approximately 20 MHz, fluorescence lifetimes are limited to ∼.1 ns and above. In addition, in the phase shift methods, only “one point” lifetimes are obtained, i.e., the entire fluorescence decay curve is not obtained.