A simple yet realistic model Hamiltonian which describes the essence of many aspects of the interaction of vibrational modes in polyatomics is discussed. The general form of the Hamiltonian is that of an intermediate case between the purely local mode and purely normal mode limits. Resonance interactions of the Fermi and Darling–Dennison types are shown to be special cases. The classical limit of the Hamiltonian is used to provide a geometrical content for the model and to illustrate the ‘‘phase-like’’ transition between local and collective (i.e., normal) mode behavior. Such transitions are evident as the coupling parameters in the Hamiltonian are changed and also for a given Hamiltonian as the energy is changed. Applications are provided to higher lying vibrational states of specific molecules (H2O, O3, SO2, C2H2, and C2D2).

A fluorinated poly(p-phenylenevinylene) analogue, co(TFPV-PV), has been prepared by copolymerization of fluorinated and nonfluorinated bissulfonium salt monomers. Conversion and yield decreased as a function of fluorine substitution. The UV-vis absorption was strongly shifted to the blue with increasing fluorine content. Complementary shifts in photoluminescence spectra were not observed, presumably because the fluorinated segments of the copolymer are very weakly luminescent relative to nonfluorinated segments. The photoluminescence spectra are therefore similar to those found for poly(p-phenylenevinylene) in the past. The co(TFPV-PV) compounds showed electroluminscence at an ac potential of ∼10 V (rms, 600 Hz) between ITO and Al electrodes. Maxima were shifted slightly to the blue with an increase in fluorine.

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