Coherent dynamics in porphyrin dimers

Abstract

A commonality among many highly efficient light harvesting protein complexes is that they exhibit strong and persistent coherent spectral signatures that coincide with the early steps of the energy transport process. Due in part to the inherent complexity and scale of protein systems, the source of these coherences remains unresolved, let alone their potential role in the light harvesting process. To overcome these challenges, we apply two-dimensional Fourier-transform spectroscopy to porphyrins and their dimers, which serve as model synthetic systems that are analogous to natural chlorophyll yet are more accessible to theoretical simulation. Combined with broadband visible excitation, this technique allows us to monitor the entire Q band region to reveal the coherent dynamics involved in the early stages of energy and charge transfer.