Spin-control of CS state lifetimes

A Series of short, sequential ET hops ensures high efficiency for formation of the CS state 

The sequence of reactions (31)—(33), illustrated in Fig. 35a for triplet ET occurring from the locally excited triplet acceptor, constitutes a potentially efficient 

ORBITAL INTERACTIONS AND LONG-RANGE ELECTRON TRANSFER 

Hviid and co-workers have recently found a way around this limitation by using the method of intermolecular triplet sensitisation to generate the locally excited triplet state of the donor chromophore in a D-A dyad.222 The sensitiser scheme is described by equations (35)-(38) and is also illustrated graphically in Fig. 36 for the case of triplet sensitisation of a donor chromophore (S is the sensitiser molecule). The principal advantage of this method is that the locally excited triplet state of one of the chromophores (in this case, the donor) is populated without invoking its 

The population of the locally exited donor (or acceptor) triplet is achieved simply by excitation of an added external triplet sensitiser molecule whose singlet energy lies below that of both donor and acceptor chromophores, but whose triplet energy lies above that of either the donor or acceptor (Fig. 36). 

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