Oxygen quenching of PtTFPP in FIB polymer: a sequential process?

Oxygen quenching of PtTFPP in FIB polymer is analyzed using a discrete exponential model (DEM), a Fِrster decay model (FDM) and a maximum entropy model (MEM). The FDM, which has been advocated for a similar system to counter presumed nonphysical dependence of the DEM amplitudes on quencher density, is discounted for the present system. Instead, the MEM is found to support the DEM in suggesting that the decay-rate distribution is bimodal, with fractional contributions that depend on quencher density. A sequential decay mechanism involving a to-be-identified intermediate state is proposed to explain this behavior.