An innovative fluorescence lifetime technique, called transient fluorescence spectroscopy, has been developed and applied toward the determination of the fluorescence lifetimes (a value near $1\mathrm{ms}$ ) of terbium doped dipicolinic acid (DPA-Tb). This different lifetime measurement technique uses a high-pulse-repetition-frequency $\left(8\mathrm{kHz}\right)$ pulsed UV laser excitation source and a slow modulated chopper $\left(50\text{to}1000\mathrm{Hz}\right)$ to produce the modulated emission intensity from the DPA-Tb, and compares these to a theoretical transient solution of the population rate equations for the DPA-Tb energy levels. Curve fitting of the transient solution of the modulated emission intensity to that obtained experimentally yielded a value for the fluorescence lifetime.