Estimation of electronic coupling for singlet excitation energy transfer
Electronic coupling is a key parameter that controls the efficiency of excitation energy transfer (EET) and exciton delocalization. A new approach to estimate electronic coupling is introduced. Within a two-state model, the EET coupling V of two chromophores is expressed via the vertical excitation...
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2014 |
| País: | España |
| Institución: | Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya) |
| Repositorio: | Recercat. Dipósit de la Recerca de Catalunya |
| OAI Identifier: | oai:recercat.cat:10256/12051 |
| Acceso en línea: | http://hdl.handle.net/10256/12051 |
| Access Level: | acceso embargado |
| Palabra clave: | Excitació nuclear Nuclear excitation Química de l'estat excitat Excited state chemistry Química quàntica Quantum chemistry |
| Sumario: | Electronic coupling is a key parameter that controls the efficiency of excitation energy transfer (EET) and exciton delocalization. A new approach to estimate electronic coupling is introduced. Within a two-state model, the EET coupling V of two chromophores is expressed via the vertical excitation energies (Ei and Ej), transition dipole moments (Mi and Mj) of the system and transition moments (μA and μB) of the individual chromophores: V = (Ei -E j){[(MiMj)(μA 2 -μB 2) -(μAμB)(M i 2 -Mj 2)]/[(Mi 2 -Mj 2)2 + 4(MiM j)2]}. These quantities are directly available from quantum mechanical calculations. As the estimated coupling accounts for both short-range and long-range interactions, this approach allows for the treatment of systems with short intermolecular distances, in particular, π-stacked chromophores. For a system of two identical chromophores, the coupling is given by V = (Ei -Ej)[(EiFj -E jFi)/(EiFj + EjF i)][1/(2 cos θ)] where Fi and Fj are the corresponding oscillator strengths and cos θ is determined by the relative position of the chromophores in the dimer. Thus, the coupling can be derived from purely experimental data. The developed approach is used to calculate the EET coupling and exciton delocalization in two π-stacks of pyrimidine nucleobases 5′-TT-3′ and 5′-CT-3′ showing quite different EET properties |
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