Abstract
A new rapid lifetime determination method (RLD) that uses a rectangular excitation is presented. The information from the exciting, as well as the emitting, portion is used to extract decay parameters for a single exponential decay. The lifetime is computed from the ratio of the integrals of the emission during the excitation period and an equal time interval during the decay (Δt). The new square-wave RLD method (SWRLD) shows speed similar to the standard RLD method but without the necessity of matching Δt to the lifetime for precise results. Monte Carlo simulations are used to predict the capabilities of the SWRLD, and the theory is tested with a luminescent terbium complex. The method is particularly applicable to rapid lifetime analysis for high-performance liquid chromatography (HPLC) and for fluorescence microscopy. It lends itself to use with inexpensive square-wave modulated light-emitting diodes (LEDs).
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