Raman spectra of polyacetylene doped with electron acceptor

The Raman spectra of a polyacetylene film doped heavily with SO3 have been measured with excitation wavelengths between 488.0 and 1064 nm. Observed Raman bands are attributed to positively charged domains generated by SO3 doping. Doping-induced changes in the Raman spectra are summarized as follows. (1) The ν1 and ν3 bands observed in the region of 1575-1485 and 1147-1112 cm−1, respectively, upshift upon doping. (2) The ν1 and ν3 bands become broad upon doping. (3) Small but significant upshifts of the ν2 band in the region of 1301-1294 cm−1 are observed upon p-type doping in contrast to downshifts for n-type doping.