ELECTRON-TRANSFER AND THE STRUCTURAL-CHANGES IN THE EXCITED-STATE

Electronic excitation followed or accompanied by electron transfer (ET) between donor (D) and acceptor (A) subsystems leads in the charge-transfer (CT) state to a relaxed molecular structure, often markedly different from the initial one. Special attention is paid to the Twisted Intramolecular Charge Transfer (TICT) excited states. Main factors determining the molecular structure (Coulombic attraction, orbital overlap between D and A, mixing of states, steric effects) are discussed for several typical cases of organic inter-molecular and intra-molecular exciplexes.