1. Ultrafast Intersystem Crossing in 9,10-Anthraquinones and Intramolecular Charge Separation in an Anthraquinone-Based Dyad
- Author
-
Michiel M. Groeneveld, Jan W. Verhoeven, Ben D. Allen, Anthony Harriman, Bartholomeus H. Bakker, Hendrik J. van Ramesdonk, James P. Rostron, and Molecular Photonics (HIMS, FNWI)
- Subjects
Photoexcitation ,Intersystem crossing ,Chemistry ,Computational chemistry ,Intramolecular force ,Femtosecond ,Ultrafast laser spectroscopy ,Singlet state ,Physical and Theoretical Chemistry ,Triplet state ,Spectroscopy ,Photochemistry - Abstract
Femtosecond transient absorption spectroscopy was employed to determine quantitatively the ultrafast S 1 -T 1 intersystem crossing in a 2-substituted 9,10-anthraquinone derivative (3), k isc = 2.5 × 10 12 s -1 . Notwithstanding this rapid process, photoexcitation of dyad 1 is followed by competition between intersystem crossing and intramolecular charge separation, the latter leading to a short-lived (2 ps) singlet charge-transfer (CT) state. The local triplet state itself undergoes slower charge separation to populate a relatively long-lived (130 ns) triplet CT state. An earlier report about the formation of an extremely long-lived CT state (>900 μs) in 1 was found to be erroneous and was related to the sacrificial photo-oxidation of the dimethylsulfoxide solvent used in that study. Finally, some important criteria have been formulated for future experimental validation of "unusually long-lived" CT states.
- Published
- 2006
- Full Text
- View/download PDF