DICHROISM IN PHOTOINDUCED INFRARED-SPECTRA OF POLYALKYLTHIOPHENES

The photoinduced infrared spectra of stretch-oriented polyhexylthiophe ne and polyoctylthiophene are reported as a function of the polarizati on both of the pump light and of the probe IR beam. There is no change in the intensity of photoinduced IR absorption due to the polarizatio n of the pump; however, the spectra show parallel dichroism when the p robe is polarized. The experimental results are analyzed on the basis of the ''effective conjugation coordinate'' theory (ECC).