Raman intensities and molecular hyperpolarizability of polyindenofluorene

A new polyconjugated polymer, poly(indenofluorene), has been studied with vibrational spectroscopy. The Raman spectrum shows a few bands with extraordinary high absolute intensity associated with the extended delocalization of the π electronic system. A vibrational method has been applied to determine the relaxation contribution to the second order hyperpolarizability γr. The combination of a large measured value of γr (3.75 × 10−33 esu per repeating unit) with the low band gap, the high stability and solubility, makes poly(indenofluorene) a promising material for technological applications