Nonlinear Stern-Volmer Fluorescence Quenching of Pyrene by C60/70

Abstract
The Stern-Volmer plot of fluorescence quenching of pyrene by C60 (or C70) is upward, and non linearly proportional to the fullerene concentration. Electronic absorption measurements show that pyrene and C60 do not form static complexes under the experimental condition. a novel “inner filter effect” model is proposed to rationalize the observed non linear upward Stern Volmer behavior. At a given C60 concentration, increasing either solvent polarity or temperature (T > 280 K) causes diminishment in the I0/I ratio. the data strongly suggest that even at concentrations far below saturation, fullerenes form aggregates in organic solvents.