Infrared and Raman studies of the radical anion of α,ω-diphenyl-1,3,5,7,9-decapentaene as a model compound in polyacetylene

The FT-infrared (IR) and Raman spectra of the radical anion of α,ω-diphenyl-1,3,5,7,9-decapentaene (DP₁₀&^dot;-), a polyene molecule with five conjugated CC bonds, were observed in vacuum condition. The IR absorption spectrum for ionic species of polyene molecule was observed for the first time in the experimental method. The CC stretching band of IR absorption has the weak at 1591-1603cm^-1, while the Raman band has the two intense peaks at 1533 and 1574cm^-1. In IR absorption, the in-plane CH bending has the several strong bands between 1448 and 1551cm^-1, whereas the Raman has a strong band used as a marker of negatively charged polyene at 1272cm^-1. The origin of IR and Raman spectra of DP10^̇- is discussed in terms of a polaron model compound in polyacetylene.