ABSTRACT
A fluorophore in an electronically excited state (which we denote by F*) can return to the ground state by a radiative pathway like fluorescence or by nonradiative pathways like internal conversion and intersystem crossing. In addition to these intrinsic pathways of de-excitation of F*, the interaction of F* with another molecule, e.g., Q, can lead to the return of F* to the ground state. Due to the presence of such an additional deactivation pathway by means of the interaction of F* with Q, the excited state population and, hence, the fluorescence intensity decrease more rapidly than in the absence of such interaction. This loss of fluorescence intensity is called fluorescence quenching [1,2]. Excitation energy transfer (EET) is one of the major intermolecular photophysical processes that affect the excited state properties of a fluorophore, leading to fluorescence quenching. EET involves nonradiative transfer of excitation energy from an excited fluorophore, which is the donor, to the acceptor molecule and occurs due to the electrostatic coulombic interaction between the transition charge densities of the donor and of the acceptor. It requires that the emission spectrum of the donor overlaps with the absorption spectrum of the acceptor,
10.1 Introduction ..................................................................................................205 10.2 Model for the Rate of Energy Transfer ......................................................... 210 10.3 Results and Discussion ................................................................................. 218 10.4 Recent Experiments on Fluorescence Quenching by Graphene................... 219 10.5 EET from Fluorophores to Doped Graphene ...............................................220 10.6 Large z Behavior of k1 and k2 ........................................................................224 10.7 Results and Discussion .................................................................................225 10.8 Summary ...................................................................................................... 227 Acknowledgments ..................................................................................................228 Appendices .............................................................................................................228
