Ultrafast dynamics of light-induced electron injection from a molecular donor into the wide conduction band of a semiconductor as acceptor

Coherent vibrational wave packet motion is shown here to survive the heterogeneous light-induced electron transfer reaction and to continue even in the product state M+. Thus, the reaction does not start from a thermally equilibrated occupation of the vibrational modes in the donor molecule M*, in contrast to the hitherto standard model applied in photoelectrochemistry. Whereas the rise of the transient absorption signals of the product states are probing the forward electron injection reaction their decay does not simply probe the recombination reaction to the ground state dye and is complicated due to several additional effects. It is postulated here that the injection of hot electrons is in general faster than the capture of hot electrons by an adsorbed molecule. (C) 2000 Elsevier Science Ltd. All rights reserved.