The decays were fit to a sum of exponentials (eq 1) to recover the fluorescence lifetimes, where Ai is the pre-exponential factor and τi is the fluorescence lifetime for each emitting species. The tail-fitting routine in the FAST software from Edinburgh Instruments was used for the fits of individual pyrene emission decays, since the EPLED-330 emission profile is narrow compared to the 2 µs collection time window. Global analysis in the FAST software was used to simultaneously fit the kinetics measured at different wavelengths. Control experiments for the emission of OTPh were performed with shorter collection times and the reconvolution of the instrument response function was used for the fit of the data to equation 1. The quality of the fits was evaluated from the c 2 values (0.9-1.2) and the randomness of the residuals. The single photon counting experiments were performed at 20 °C.