Intra-chain exciton generation by charge recombination in substituted polyacetylenes

Nascent excited state dynamics, following photoexcitation by 25 fs optical pulses, is detected in a degenerate ground state conjugated polymer with transverse conjugation, namely poly di-phenyl acetylene. Pumping 1.1 eV above the optical gap generates correlated polaron pairs, whereas the majority of the neutral singlet excited states are formed in a secondary process upon geminate recombination of polaron pairs. When the exciting photons have lower energy, close to the optical absorption edge, only singlet states are formed.