Quantifying Through-Space Charge Transfer Dynamics in π-Coupled Molecular Systems

This work probes the relation between the rate of charge delocalization and the strength of through-space π-π coupling in stacked aromatic systems. With resonant photoemission we determine charge transfer (CT) dynamics in two molecular bi-layer systems with different inter-ring separation, [2,2]paracyclophane (22PCP) and [4,4]paracyclophane (44PCP) adsorbed on Au(111), which allows us to quantitatively probe the carrier transport as a function of inter-ring coupling strength. A.Batra et al.; http://www.nature.com/ncomms/journal/v3/n9/full/ncomms2083.html

We use the core-hole clock implementation of resonant photoemission spectroscopy to study the femtosecond charge-transfer dynamics in cyclophanes, which consist of two precisely stacked π-rings held together by aliphatic chains. We study two systems, [2,2]paracyclophane (22PCP) and [4,4]paracyclophane (44PCP), with inter-ring separations of 3.0 Å and 4.0 Å respectively. We find that charge transport across the π-coupled system of 22PCP occurs in 2fs whereas it is 20 times slower in the 44PCP. We attribute this difference to the reduced inter-ring electronic coupling in 44PCP, and illustrate the use of core-hole clock spectroscopy as a general tool for quantifying through-space coupling in π-stacked systems Retrieve article
Quantifying Through-Space Charge Transfer Dynamics in π-Coupled Molecular Systems, Arunabh Batra, Gregor Kladnik, Héctor Vázquez, Jeffrey S. Meisner, Luca Floreano, Colin Nuckolls, Dean Cvetko, Alberto Morgante, Latha Venkataraman
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