NON A PRIORI ANALYSIS OF FLUORESCENCE DECAY SURFACES OF EXCITED-STATE PROCESSES .2. INTERMOLECULAR EXCIMER FORMATION OF PYRENE

The so-called global compartmental approach to analyze the kinetics of excited-state processes (Ameloot et al., preceding paper) is tested on simulated and real fluorescence data of the excimer formation of pyrene in a nonviscous solvent. The identifiability problem of a bicompartmental system is verified. The results of the bicompartmental analysis are compared to the results of the classical analysis. The following rate constant values for the excited-state processes of pyrene in isooctane at room temperature are obtained by the bicompartmental analysis: k01 = 2.17 X 10(6) s-1, k21 = 7.2 X 10(9) s-1 M-1, k02 = 14.8 X 10(6) s-1, and k12 = 5.7 X 10(6) s-1. The evidence for the nonexistence of ground-state dimers of pyrene in isooctane for concentrations lower than 1.5 X 10(-3) M is demonstrated. The species associated emission spectra (SAEMS) of the monomer and the excimer emission are calculated. It is shown that the unsubstituted intermolecular pyrene excimer is emitting at 375 nm.