Ultrafast charge transfer through p-oligo(phenylene) bridges: effect of nonequilibrium vibrations

Details

Serval ID
serval:BIB_3ADBFB3F87E5
Type
Article: article from journal or magazin.
Collection
Publications
Title
Ultrafast charge transfer through p-oligo(phenylene) bridges: effect of nonequilibrium vibrations
Journal
Current Science
Author(s)
Bauer C., Teuscher J., Pelet S., Wenger B., Bonhôte P., Nazeeruddin M.K., Zakeeruddin S.M., Comté P., Grätzel M., Moser J.E.
ISSN
0011-3891
Publication state
Published
Issued date
2010
Volume
99
Number
9
Pages
343-352
Language
english
Abstract
Electron transfers (ET) between a donor (D) and an acceptor (A) through a molecular bridge (B) are of great importance in biological systems, molecular electronics and molecular based light-energy conversion systems. Here, the back and the forward electron transfer rates have been measured by femtosecond and nanosecond spectroscopy in a heterogeneous donor-bridge-acceptor (D-B-A) system, where D = ruthenium terpyridine complex, B = p-oligo(phenylene) and A = TiO(2). The forward ET rate (from 0.85 to 3.7 ps(-1)) is faster than the nonequilibrium vibrations relaxation rate of the hot (3)MLCT (metal-to-ligand charge transfer) state of the donor (12 ps(-1) in solution). The back ET occurs on the microsecond time scale. Regarding the distance dependence behaviour, damping factors 0.16 and 0.47 angstrom(-1) of the forward and the back ET respectively are obtained. These results confirm that the damping factor is not only linked to the nature of the molecular bridge but to the full D-B-A system. This unusual low damping factor observed for the forward ET is attributed to a decrease of the tunnelling energy gap Delta E, which is induced by the nonequilibrium vibrations at the donor-bridge interface. This enhanced electron transmission is briefly discussed within the concept of a nonequilibrium polaron relaxation towards the dissipative acceptor. In this case, the dissipation of the excess vibrational energy and the electron transfer occur in a synchronized cooperative way.
Keywords
Cooperative effect, molecular electronics, nonlinear phenomena, nonequilibrium phenomena, synchronization, vibronic coupling
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Create date
01/10/2012 14:36
Last modification date
20/08/2019 13:30
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