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Science and Technology of Synthetic Metals, 1994. ICSM '94. International Conference on

Date 24-29 July 1994

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  • International Conference on Science and Technology of Synthetic Metals - ICSM '94 [front matter]

    Publication Year: 1994, Page(s):i - iv
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  • Ultrafast optical probes of excited states in conducting polymers

    Publication Year: 1994, Page(s): 4
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    Summary form only given. The question whether the electronic states of 7/spl pi/-conjugated polymers can be described by a band model or exciton model, has been extensively debated over the last couple of years. We present an overview of relevant ultrafast optical data, such as transient photoluminescence, gain, and photomodulation, obtained from several luminescent (such as poly-(arylene vinylene... View full abstract»

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  • Nature of the primary photo-excitations in poly(arylene-vinylenes)

    Publication Year: 1994, Page(s): 4
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    Summary form only given. We present an overview of the optical properties and related experimental results obtained from poly(paraphenylene vinylene), PPV, and its soluble derivatives, and we critically examine the interpretation of these data in the context of both the band model and the exciton model of the electronic structure of these semiconducting and luminescent polymers. Results obtained f... View full abstract»

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  • Magnetic-field effects on the reentrance transition of the alloy of pristine and fully deuterated (DMeDCNQI)/sub 2/Cu

    Publication Year: 1994, Page(s): 5
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    Summary form only given. The title compound undergoes a metal-insulator-metal reentrance transition with decreasing temperature. The metal-insulator transition occurring at the higher transition temperature has been ascribed to the combination of a Peierls instability in the /spl pi/ -like band of DCNQI molecular stacks and the so-called 4K/sub F/ instability of d-like band of copper ions. We inve... View full abstract»

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  • Theory of metal-insulator transition in (DCNQI)/sup2/Cu

    Publication Year: 1994, Page(s): 5
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    Summary form only given. The metal-insulator transition of (DCNQI)/sub 2/Cu has various unique features; 1) The transition is of first order with very large hysterisis. 2) In the insulating phase there exists threefold superlattice distortions. 3) Although the temperature independent Pauli like spin susceptibility is observed in the metallic state, the localized spins are created in the insulating... View full abstract»

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  • Selectively deuterated molecular conducfor (DMe-DCNQI)/sub 2/-phase diagram and dimensionality

    Publication Year: 1994, Page(s): 6
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    Summary form only given. Conducting molecular system (R/sup 1/,R/sup 2/-DCNQI)/sub 2/Cu consists of one dimensional DCNQI columns, each of which is three-dimensionally linked by the coordination bond (Cu-N). P//sup/spl pi-d// interaction in this system provides unique electrical and magnetic properties. (DMe-DCNQI)/sub 2/Cu undergoes novel metal-insulator-metal (reentrant) transition under very lo... View full abstract»

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  • Properties of synthetic derivatives of buckminsterfullerene in conposites with conducting polymers

    Publication Year: 1994, Page(s): 6
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    Summary form only given. Studies of photoinduced electron transfer from a conducting polymer to C/sub 60/ and C/sub 61/ derivatives with 60 and 58 /spl pi/ electrons will be described. The molecules with 58 /spl pi/ electrons are the methanofullerenes; e.g., 1 and the molecules with 60 /spl pi/ electrons are the fulleroids (2). These molecules were made into composites with conjugated polymers suc... View full abstract»

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  • Photophysical properties of fullerene-conducting polymer system

    Publication Year: 1994, Page(s): 7
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    Summary form only given. Optical properties of conducting polymers such as absorption spectrum, photoluminescence, electroluminescence, photo-magnetic effect, photoconductivity and their dynamics change drastically upon doping of small amount of fullerene. Electrical and optical characteristics of junctions based on conducting polymers and fullerene are also anomalous. It should be mentioned that ... View full abstract»

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  • Addition reactions of fullerenes

    Publication Year: 1994, Page(s): 7
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    Summary form only given. In order to minimise strain in the the carbon cage, there is relatively little electron delocalisation in fullerenes, which therefore behave as giant (electron deficient) alkenes. They therefore undergo all the reactions typical of alkenes such as hydrogenation, halogenation, alkylation, alkylation, hydroxylation, metallation etc; the electron deficiency also makes them ex... View full abstract»

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  • Theory of bi-excitons in /spl pi/-conjugated polymers

    Publication Year: 1994, Page(s): 8
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (89 KB)

    Summary form only given. Theoretical models of /spl pi/-conjugated polymers that emphasize the Coulomb electron-electron correlations predict that the lowest optidal excitation is to an exciton. We have extended our theoretical studies to an energy region that is much higher, to probe specifically the states that are reached by two-electron excitations from the ground state. Theoretical evidence f... View full abstract»

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  • Metallic transitions of soliton lattice in conducting polymers randomly doped

    Publication Year: 1994, Page(s): 8
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    Summary form only given. Metallic transitions are theoretically investigated for a chain of trans- polyacetylene with an assumption of random impurity distributions, effects of excess charges by the dopants being represented by the introduction of the soliton lattice. Harigaya and Terai carried out a computer simulation work to find that the energy gap vanishes at the right impurity concentration.... View full abstract»

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  • Pinning of /spl pi/ electrons in polyconjugated systems and frequency dispersion of the R mode (amplitude mode)

    Publication Year: 1994, Page(s): 9
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    Summary form only given. The correlative study of the Raman spectra (recorded in our laboratory) of series of oligomers of several classes of polyconjugated materials shows that the frequency and intensity dispersion of the R mode (amplitude mode) greatly changes in the different classes . This fact reflects the pinning of /spl pi/ electrons within the various chemical groups. This phenomenon is a... View full abstract»

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  • Localization in quasi-one-dimensional systems

    Publication Year: 1994, Page(s): 9
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    Summary form only given. The conductance in a polymeric system of nearly macroscopic dimensions is calculated using the many-channel Buttiker-Landauer formula. The conductance is studied as a function of various types of irregularities including on-site disorder, disorder in the intrachain hopping caused by chain twisting and sp/sup3/ defects, and disorder due to variations in the interchain order... View full abstract»

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  • Structural and physical properties of charge transfer complexes with [M(dto)/sub 2/ anions (M:Ni,Pt,Cu,Pd; dto:DITHIOOXALATE)

    Publication Year: 1994, Page(s): 10
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    Summary form only given. We report the structural, electrical and magnetic properties of the charge transfer complexes of [M(dto)/sub 2/](M=transition metals) as electron acceptors and TTF derivatives. Three dimensional alternating stacks of donor dimer and anion molecule are observed in the 2:1 complexes of BEDT-TTF and BEDO-TTF with M (dto)/sub 2/(M=Ni, Pd). While BEDT-TTF complex with Pt(dto)/s... View full abstract»

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  • Molecular metals based on pd(dddt)/sub 2/ complexes

    Publication Year: 1994, Page(s): 10
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    Summary form only given. The M(dddt)/sub 2/ complexes (dddt2- = 5,6-dihydro-1,4dithiin-2,3 dithio late) arouse great interest for they are isolobal analogs of the molecule BEDT-TTF [1] which is known to form superconducting cation radical salts [2]. In this work the first cation salts of Pd(dddt)/sub 2/ with the anions different in their geometry and electronic configuration (IBr/sub 2/, C10/sub 4... View full abstract»

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  • Recent developments in the chemistry of sulphiur-donor ligands

    Publication Year: 1994, Page(s): 11
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    Summary form only given. Over the past decade extensive studies have been made on the metal complexes of sulphur donor ligands. This has resulted in their use as building blocks in the synthesis of molecular metals and superconductors and as third order non-linear optical materials/sup 1,2/. To aid the understanding of the relationships between molecular structure and solid state properties and to... View full abstract»

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  • Magnetism in organic materials

    Publication Year: 1994, Page(s): 12
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    Summary form only given. Tailoring magnetic interactions of organic solids is currently an area of intense research activity. The cooperative efforts of chemists and physicists resulted in the preparation and analysis of a variety of new materials. Neutral monoradical solids and radical cation salts were used to study the variation of intermolecular exchange interaction with molecular packing and ... View full abstract»

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  • A spectroscopic analysis of photochemical processes in fullerenes

    Publication Year: 1994, Page(s): 12
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    Summary form only given. Raman spectroscopy is employed as a probe of photochemical processes in both oxygen-free and oxygenated samples of C/sub 60/. The amplitude of the peaks are observed to be sensitive to light exposuro. Each of the initially observed peaks degrades while new peaks emerge approximately ten wavenumbers to the low energy side. In oxygenated films, the degradation process is obs... View full abstract»

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  • Electronic excited states in C/sub 60/ thin film as revealed by luminescence measurement: excitation spectra and temperature dependence

    Publication Year: 1994, Page(s): 13
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    Summary form only given. Important information pertaining to electronic excited states and their relax ation processes in solid C60 can be obtained by the measurement of luminescence and photoconductivity. We have recently succeeded in obtaining a hither to unknown luminescence excitation spectrum of C60 thin film exhibiting well resolved vibronic structures In the optical edge region. These struc... View full abstract»

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  • Magnetoresistance of carbon nanotube bundles

    Publication Year: 1994, Page(s): 13
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (93 KB)

    Summary form only given. Since the discovery of carbon nanotubes a large number of theoretical studies predicted that their band gap changes significantly between zero and nonzero values depending on the diameter and degree of helicity of the nanotube. A magnetic field is expected either to reduce the band gap or to produce Aharonov-Bohm oscillations, when the tube axis is perpendicular or paralle... View full abstract»

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  • Photophysics of semiconducting polymer- C/sub 60/ composites: a comparative study

    Publication Year: 1994, Page(s): 14
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    Summary form only given. Experimental results on the metastable, reversible, ultrafast photoinduced electron transfer between semiconducting, conjugated polymers and buckminsterfullerene, C/sub 60/, are summarized. Comparative studies with different semiconducting polymers as donors demonstrate that in the degenerate ground state polymers soliton excitations form before the electron transfer can o... View full abstract»

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  • Role of the dopant counter-ions in the transport and magnetic properties of disordered conducting polymers

    Publication Year: 1994, Page(s): 14
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (94 KB)

    Summary form only given. Disordered conducting polymers like polypyrroles or even some of the polyanilines contain generally short electroactive chains with conjugation lengths of a few ten monomers. Most of the electronic properties of these materials cannot be really understood in terms of quasi-one-dimensional models. i) Why in the fully doped materials the number of Curie spins is always lower... View full abstract»

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  • ESR in conducting polymers: effect of oxygen and air

    Publication Year: 1994, Page(s): 15
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    Summary form only given. It has been known since the fifties that the ESR signal of the free spins in various compounds is reversibly broadened in presence of air. In conducting polymers such an effect has been reported/sup 1/ to be a signature of the conducting state : in the conducting state, the spin/charge carriers can move to the surface and come into contact with the paramagnetic molecular o... View full abstract»

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  • Kondo effect in a tomonaga-luttinger liquid

    Publication Year: 1994, Page(s): 15
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    Summary form only given. Kondo effect of the magnetic impurity in a interacting one-dimensional (ID) electron system, i.e., Toinonaga-Luttinger liquid, is studied. This problem is relevant to the /spl pi/ - d system, where the /spl pi/ band constitutes the 1D electron system. By using the poor rnan's scaling method, it is found that the Kondo coupling flows to strong coupling regime not only for a... View full abstract»

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  • Comparing the spin density distribution in radical anions of several different oligomeric /spl pi/-chains

    Publication Year: 1994, Page(s): 16
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    Summary form only given. We have studied the spin density distribution in a large number of radical ions, of oligomeric series of differently linked /spl pi/-systems as oligo-(ortho-, meta-, and paraphenylenevinylene)s la-c, oligoenes 2, -naphthylenes 3, -anthryienes 4, and -rylenos 5 by EPR/ENDOR and optical absorption spectroscopy. The results obtained show very different features depending on t... View full abstract»

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