How can infra-red excitation both accelerate and slow charge transfer in the same molecule?

Published

Journal Article

A UV-IR-Vis 3-pulse study of infra-red induced changes to electron transfer (ET) rates in a donor-bridge-acceptor species finds that charge-separation rates are slowed, while charge-recombination rates are accelerated as a result of IR excitation during the reaction. We explore the underpinning mechanisms for this behavior, studying IR-induced changes to the donor-acceptor coupling, to the validity of the Condon approximation, and to the reaction coordinate distribution. We find that the dominant IR-induced rate effects in the species studied arise from changes to the density of states in the Marcus curve crossing region. That is, IR perturbation changes the probability of accessing the activated complex for the ET reactions. IR excitation diminishes the population of the activated complex for forward (activationless) ET, thus slowing the rate. However, IR excitation increases the population of the activated complex for (highly activated) charge recombination ET, thus accelerating the charge recombination rate.

Full Text

Duke Authors

Cited Authors

  • Ma, Z; Lin, Z; Lawrence, CM; Rubtsov, IV; Antoniou, P; Skourtis, SS; Zhang, P; Beratan, DN

Published Date

  • August 2018

Published In

Volume / Issue

  • 9 / 30

Start / End Page

  • 6395 - 6405

PubMed ID

  • 30310568

Pubmed Central ID

  • 30310568

Electronic International Standard Serial Number (EISSN)

  • 2041-6539

International Standard Serial Number (ISSN)

  • 2041-6520

Digital Object Identifier (DOI)

  • 10.1039/c8sc00092a

Language

  • eng