Electron transfer in multiply bridged donor-acceptor molecules: Dephasing and quantum coherence.
We present a simple theoretical treatment of nonadiabatic electron transfer in multiply bridged donor-bridge-acceptor molecules using the density matrix formalism. Destructive interference can result from different signed couplings between bridge sites, with the simplest system being a four-site Joachim-type molecular interferometer. Previous work has shown that deposition of energy on the bridge sites erases the interference and recovers transport. We show that pure local dephasing, a completely elastic process, is also capable of eliminating destructive interference and regaining transport. Destructive interference as a result of system connectivity can explain the familiar ortho-meta-para reactivity of benzene bridges. We also show that pure dephasing can yield a coalescence of ortho, meta, and para effective coupling strengths and suggest a system to observe this effect experimentally.
Goldsmith
Randall H
RH
Center for Nanofabrication and Molecular Self-Assembly, Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA.
Wasielewski
Michael R
MR
Ratner
Mark A
MA