INFRARED STUDIES OF OPTICALLY-EXCITED POLYDIACETYLENE

Photo-induced absorption (PA) is observed for the polydiacetylene PDA-1OH in the infrared which is found to be consistent with the photogeneration of charged bipolarons. No comparable PA is seen in PDA-TS, a result that is consistent with photo-excitation leading to the formtaion of triplet excitonic bipolarons. Persistent effects are observed for PA in PDA-1OH indicating a long carrier lifetime due to trapping. Electron correlation is significant and shifts the electronic transitions to lower energy in PDA-1OH so that overlap of electronic and vibrational transitions occurs. This overlap leads to strong anti-resonances in the PA due to electron-photon interaction.