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Dinámica no adiabática ultrarrápida de [Fe ((II) ((bpy) ((3))) ((2+) en solución
Wojciech Gawelda1, Andrea Cannizzo, Van-Thai Pham
1Ecole Polytechnique Fédérale de Lausanne, Laboratoire de Spectroscopie Ultrarapide, Faculté des Sciences de Base, ISIC-BSP, Lausanne, Switzerland.
Journal of the American Chemical Society
|June 15, 2007
Resumen
La relajación ultrarrápida en el hierro (II) -tris (bipiridina) se produce a través de un rápido cruce intersistémico (ISC) de los estados singlet a triplet, seguido de la población del estado quinteto. Este proceso es independiente del acoplamiento de espín-órbita de metal.
Área de la Ciencia:
- La fotoquímica es la fotoquímica.
- Espectroscopia ultrarrápida Espectroscopia ultrarrápida.
- Coordinación Química de la Coordinación
Sus antecedentes:
- Los complejos de hierro (como el hierro (II) -tris (bipiridina) son cruciales en la fotoquímica.
- Comprender la dinámica del estado excitado es clave para diseñar nuevos materiales fotoactivos.
- Los procesos ultrarrápidos gobiernan los pasos iniciales de las reacciones fotoquímicas.
Objetivo del estudio:
- Para caracterizar las vías de relajación ultrarrápida de hierro acuoso (II) -tris (bipiridina) después de la excitación.
- Para determinar las escalas de tiempo del cruce intersistémico (ISC) y la posterior relajación.
- Para investigar el papel de la interacción espín-órbita en la dinámica de relajación.
Principales métodos:
- Espectroscopia de fluorescencia de conversión hacia arriba en femtosegundos.
- Espectroscopia de absorción transitoria (TA) de femtosegundos. espectroscopia de absorción transitoria (TA) de femtosegundos. espectroscopia de absorción transitoria (TA) de femtosegundos. espectroscopia de absorción transitoria (TA) de absorción transitoria (TA) de absorción transitoria (TA) de absorción transitoria (TA) de absorción transitoria (TA) de absorción transitoria (TA) de absorción transitoria) de absorción transitoria (TA) de absorción transitoria (TA) de absorción transitoria (TA) de absorción transitoria (TA) de absorción transitoria (TA) de absorción transitoria (TA) de absorción transitoria (TA) de absorción transitoria) de absorción transitoria (TA) de absorción transitoria (TA) de absorción transitoria (TA) de absorción transitoria (TA) de absorción transitoria (TA) de absorción transitoria (TA)
- Descomposición del valor singular y análisis global de los datos de TA.
Principales resultados:
- Se observó una emisión de transferencia de carga de metal a ligando (1MLCT) de vida muy corta (<20 fs).
- Se caracterizó el cruce intersistémico (ISC) a un estado triple de transferencia de carga de metal a ligando (3MLCT) (<150 fs).
- Se identificaron tres escalas de tiempo distintas (120 fs, 960 fs, 665 ps) correspondientes al decaimiento 3MLCT, la población del estado del quinteto y el decaimiento.
Conclusiones:
- La alta tasa de ISC es independiente de la constante de la órbita de giro del metal, lo que sugiere un mecanismo que implica cruces evitados.
- Un modelo de cruces evitados entre las curvas de energía potencial singlet y triplet explica las tasas de CSI observadas.
- La disipación de energía se produce rápidamente (2000 cm-1/100 fs) y es consistente con la regla de oro de Fermi.
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