Polarized reflectivity spectra of stretch-oriented poly(p-phenylene-vinylene)

We report polarized, near-normal incidence, absolute reflectivity spectra of highly stretch-oriented unsubstituted poly(p-phenylene-vinylene). The data show a well-resolved vibronic progression in the lowest optical transition, a high dichroic ratio and weak signals due to conjugated segments with reduced effective conjugation length. On the high-energy side of the spectra, other transitions mainly related to excited states involving localized levels are detected. The low-temperature spectra confirm these assignments. The polarization properties of the reflectivity spectra are discussed in relation to correlated quantum–chemical calculations.