Ultra-fast electron transfer

Photoexcitation of the aqueous Zn(II)porphyrin-methylviologen complex leads to ultrafast forward and back electron transfer: tau(FET) = 180 fs, tau(BET) = 700 fs. The excess energy of the excitations survives both electron transfer steps, leading to hot ground states. Variation of excitation energy (S2 vs. S1 excitation) influences the product distribution of this two-step electron transfer. A series of similar complex showed a Marcus normal region free energy dependence, supporting our hypothesis that the reaction from the S2 state occurs via electronically excited radical pairs.

References

1. J. Petersson et al., J. Am. Chem. Soc. 2009, 123, 7940-7941
2. J. Petersson et al., 2012, in preparation.