Ground and Excited State Molecular Interactions

Energy and Electron Transfer (Excited State Interactions and Reactions) 

A transfer of the excitation energy from the donor to the acceptor will occur when an energy acceptor molecule is placed at the proximity of an excited energy donor molecule. After energy transfer, the donor relaxes to its ground state and the acceptor is promoted to one of its excited states. A photo-induced electron transfer can be initiated after photoexcitation when an excited single electron in the LUMO of the electron donor is transferred to a vacant molecular orbital (LUMO) of the acceptor. 

The mechanisms for the energy and electron transfers are outlined below. 

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J G 1994. Extended Electron Distributions Applied to the Molecular Mechanics of Some termolecular Interactions. Journal of Computer-Aided Molecular Design 8 653-668. el A and M Karplus 1972. Calculation of Ground and Excited State Potential Surfaces of anjugated Molecules. 1. Formulation and Parameterisation. Journal of the American Chemical Society 1 5612-5622. 

The principle behind this investigation is electrochromism or Stark-effect spectroscopy. The electronic transition energy of the adsorbed chromophore is perturbed by the electric field at the electric double layer. This is due to interactions of the molecular dipole moment, in the ground and excited states, with the interfacial electric field induced by the applied potential. The change in transition frequency Av, is related to the change in the interfacial electric field, AE, according to the following ... 

All the terms in our transformed Hamiltonian were already derived by Agranovich [46] in the discussion of clusters of two-level molecules interacting via electrostatic forces. The main novelty of the proposed approach is that it is based on local (molecular) ground and excited states as obtained in the mf approximation and therefore it explicitly accounts for the dependence of the local ground and excited state on the supramolecular interactions. In the standard approach instead the term in (bl H-fc ) in Eq. (12) is disregarded 46], and the local wave functions do not depend on tire supramolecular geometry. The strength of our approach is in its ability to follow the evolution of the properties of the supramolecular systems... 

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