Electronic coupling matrix element for electronic excitation energy transfer: S-1 S-1 -> S-2 S-0 excited state annihilation

Abstract

For the singlet-singlet annihilation process S1S1S2S0, an expression is derived for the electronic coupling matrix element involved in electronic excitation energy transfer (EET) between two equivalent chromophores. Allowance is made for vibronic coupling to occur between the S1 and S2 states of the chromophores, for each of which the S1←S0 and S2←S0 excitations are, respectively, electric-dipole forbidden and allowed. Attention is also given to aspects of the theory for singlet-singlet (πDπD*) (nAnA)→(πDπD) (nAπA*) EET with vibronic coupling. The theory for S1S1→S2S0 is illustrated via the results of some model calculations for two CS chromophores. For each chromophore, the calculations tre..