Absorption spectra (2.0–6.1 eV) for poly[(2-methoxy, 5-($2^{\prime }$-ethyl)-hexyloxy) paraphenylene vinylene] oriented by gel processing in polyethylene show that the bands peaking at 2.5, 3.6, and 6 eV are polarized parallel to the draw direction, while the band at 4.7 eV is polarized off axis. Although the onset of absorption in oriented samples is redshifted from that in disordered, spin-cast films, indicating significantly higher conjugation lengths, the 3.6-eV band is present in both. Thus, the 3.6-eV band is an intrinsic feature of the electronic structure of the macromolecule and not a characteristic of oligomers or polymers with short conjugation lengths.

• Received 14 October 1998

DOI:https://doi.org/10.1103/PhysRevB.59.4661