Excitonic and phonon-mediated optical Stark effects in a conjugated polymer

Abstract

We have investigated the subresonant optical response of the polydiacetylene PTS using stimulated inverse Raman spectroscopy. The data exhibit energy-dependent line-shape variations which are caused by the optical Stark effect on the exciton-phonon and exciton--ground-state transitions. These are the first observations of both phonon-mediated and excitonic optical Stark effects in a 1D conjugated polymer. Excellent agreement is achieved between the data and our calculations using a theory of phonon-mediated changes in susceptibility.