Fast Analog Technique For Determining Fluorescence Lifetimes Of Multicomponent Materials By Pulsed Laser

This paper describes a system capable of measuring fluorescent lifetimes and time-resolved spectra of microscopic particles, thus substantially enhancing the usefulness of fluorescence microscopy as a characterizing tool. Tests and applications of this technique for identifying component lifetimes (in the nanosecond and subnanosecond range) and spectra in organic model compounds also are described. A multi-exponential decay fit to the data yields fluorescence decay times, percentage contributions (fractional intensities) and time-resolved spectra for each decay. Two-component non-interacting mixtures are resolved if the decay times differ by a factor of two and the percentage contribution from each fluorophore is more than 10%. For three-component mixtures, it is necessary for the resolution of the lifetimes that the decay times differ by at least a factor of three and the percentage contribution from each component be more than 15%.