The conductivities of all the currently reported conducting polymers are compared to those of the classical metals. The requirements for a technologically useful conducting polymer are considered and the degree to which existing conducting polymers meet these requirements is evaluated. The mechanism of doping is discussed together with the final state of the dopant and the polymer. The available structural data are described as well as the problems of structurally characterizing these systems. Some of the problems of inhomogeneous distribution of dopant species are also pointed out.

Conducting polymers: a review of recent work

IR and Raman studies of polythiophene prepared by electrochemical polymerization

In the presence of KI, iodine crystals dissolve rapidly in an aqueous solution forming triiodide ions (I3-) and other neutral species The experimental evidence does not support the formation of polyiodide ions such as I5-, I7-, etc in the solution However, there is a strong evidence suggesting the formation of polyiodine species, I2x, where x = 2, 3, etc, stabilized by H+ ions in the solution Ab initio results are presented for structures and energies of some of these species with an x value of up to 4 Each geometry optimization was done at the HF/LANL2DZ level followed by a single-point energy calculation at the MP2/LANL2DZ level These calculations suggest that the isolated polyiodine species are not stable and, among the complexed species, the protonated clusters are most stable

Polyiodine and Polyiodide Species in an Aqueous Solution of Iodine + KI: Theoretical and Experimental Studies

Absorption spectroscopy of octahedral nickel(II) complexes: A case study of interactions between multiple electronic excited states

Electronic spectral studies and solvent effects on the reaction of iodine with 1,4,8,11-tetraazacyclotetradecane

A selective resonant Raman enhancement is observed in solid films of the blue complex formed between starch and iodine. The intensity of the 162-${\mathrm{cm}}^{\ensuremath{-}1}$ phonon peak is strongly enhanced when the laser frequency is resonant with the main electronic absorption band at \ensuremath{\simeq} 590 nm, whereas the 112-${\mathrm{cm}}^{\ensuremath{-}1}$ phonon is strongly enhanced when the laser frequency is tuned in the blue region in resonance with the shoulder at \ensuremath{\simeq} 455 nm. Similar behavior has been observed in a number of compounds containing polyiodide chains such as iodinedoped polyvinyl alcohol, sulfur polynitride, and polyacetylene. A theoretical explanation of this phenomenon is given in terms of the theory of resonant secondary emission, and explicit analytical expressions for the Raman cross sections as a function of the exciting wavelength are derived for the case of resonance with broad and structureless absorption bands (i.e., a rapidly relaxing system with strong electron-vibration interactions). A structural model for the chromophore of these compounds is also proposed.

Selective resonant Raman enhancement in polyiodide chains

Experimental evidence of two-phonon vibronic progressions due to second-order linear electron-phonon interactions is obtained in Ni${\mathrm{Cl}}_{2}$ and Ni${\mathrm{Br}}_{2}$ crystals, by comparing the phonon structure observed in $^{3}A_{2}(F)\ensuremath{\rightarrow}^{1}E(D)$ transition with Raman data. The vanishing of the spin-dependent first-order electron-phonon interaction is shown to be a necessary condition for observing prominent second-order phonon structures in isoconfigurational crystal-field transitions. According to this rule we predict and discuss the appearance of second-order progressions in other $d$-metal layered compounds.

R. Tubino

Papers

Selective resonant Raman enhancement in polyiodide chains

Erratum: Evidence of two-phonon vibronic progressions in layered 3 d metal dihalides

Resonant Raman scattering of polymeric sulfur nitride modified by iodine