Explaining the long coherence effects in photosynthetic exciton energy transfer as observed by 2D photon echo spectroscopy: TCPS model

Abstract

We propose a simple stochastic model which successfully explain the longcoherence effects observed in photosynthetic EET by 2D photon echoexperiments of G. S. Engel et. al. (Nature, {f 446} 782, (2007)). OurTwo-Component Phonon Spectrum (TCPS) model is based upon the division ofphonon degrees of freedom into systematic component (treated through Polarontransformation) and the stochastic component (treated through dynamicaldisorder). This model successfully explain the observed long coherence upto$ sim 600 fsec$ in EET experiments and it uses the information of homogeneous broadening from 2-D photon echo spectrum.