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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 22 (1989), S. 1669-1675 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 110 (1988), S. 7647-7651 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 3331-3337 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: To examine the conformation of polyanilines with different degrees of oxidation two three-ring oligomers, N-N'-diphenyl-1,4-phenylenediamine (the "amine trimer'') and N-N'-diphenyl-1,4-benzoquinodiimine (the "imine trimer'') have been studied. The amine and imine trimers are model molecules for leucoemeraldine and pernigraniline, respectively. MNDO calculations for the cis and trans forms of the imine trimer predict the ground states to have almost identical energies. Both forms have the quinoid ring in the plane of the backbone and the torsion angle between the quinoid and benzenoid rings close to 90°. The density of valence states (DOVS) and optical absorption were calculated for different conformations of the amine and imine molecules using the CNDO/S3 model. Comparison of the calculated DOVS with photoemission data for the amine molecules indicates a conformation about the same as that predicted by MNDO for the ground state. The optically excited state for the amine, according to the comparison between calculated and measured optical absorption, could have the same geometry or possibly exhibit a larger torsion angle. In the case of the imine molecule, however, the existence of a low energy absorption at 2.8 eV requires the optically excited state to have a different geometry from that predicted by MNDO for the ground state. Analysis of the optical absorption using the CNDO/S3 model suggests that the quinoid ring is twisted out of the plane of the nitrogen backbone by ∼55° while the benzenoid ring is twisted by about the same angle in the opposite direction. The DOVS resulting from this conformation describes the photoemission data reasonably well, although these data are not well described by DOVS obtained using the "ground state'' conformation predicted by the MNDO model.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 3414-3423 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The CNDO/S3 molecular orbital model is applied to describe the electronic structure of aniline, (C6H5)NH2, emeraldine, (C6H5)N(C6H4)N(C6H4)NH(C6H4)NH2, its hydrogenated and dehydrogenated forms, and its singly and doubly protonated forms. The cation eigenvalue spectrum, i.e., density of valence states (DOVS), is found to be sensitive to molecular conformation which, in turn, can be inferred from comparison of the calculated DOVS with suitable measured photoemission spectra. For fixed molecular conformation, the major effect of hydrogenation of emeraldine is the occupation of its lowest empty molecular orbital with accompanying electronic and atomic relaxation. Dehydrogenation leads to the emptying of its highest filled molecular orbital. Protonation leads to rearrangements of the valence electron charge among the filled orbitals but not to deviations from a closed shell system. Protonation-induced atomic relaxation can create major changes in the character of the highest filled or lowest empty orbitals. Changes in molecular conformation (e.g., upon hydrogenation or protonation) can yield large alterations in both the DOVS and the character of the radical cation eigenstates. Comparison of calculated DOVS with photoemission spectra from thin films of polyemeraldine does not suffice to determine the molecular conformation, however, because of the low resolution of the measured spectra.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 9175-9180 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In the model of high-field hopping studied extensively by Bässler and collaborators, disorder arising from the varying intersite wave function overlap (off-diagonal disorder) was incorporated by random assignment of an overlap decay rate to each site independently, admittedly an arguable procedure. We have carried out Monte Carlo simulations incorporating assignment of a random overlap to each bond. The assumptions of a Gaussian density of states and a Miller–Abrahams type of elementary jump rate were retained. We find the value and field variation of the mobility to be quite sensitive to the model of off-diagonal disorder considered. However, the results of our simulations may also be fitted by an exponential dependence of mobility on the square root of field for some ranges of field and parameters of the disorder.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Materials Research 8 (1978), S. 135-179 
    ISSN: 0084-6600
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 96 (1992), S. 2827-2830 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 3822-3824 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It has been suggested that Poole–Frenkel behavior, i.e., the linear dependence of the log of the mobility μ on the square root of the electric-field intensity, found for many conjugated polymer films is due to the interaction between the charge carriers and randomly distributed permanent dipoles. However, the dipole concentration in the polymers is much too small to achieve this. We show that introduction of short-range correlation between the energies of the hopping sites, on the scale of the coherence length measured by x rays, can account for the field and temperature dependence of films of poly(2-methoxy,5-(2′-ethyl-hexoxy)–p-phenylene vinylene), a representative conjugated polymer. We investigate also the effects of inhomogeneity on the field and temperature dependence of μ. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 1518-1520 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It has been accepted that addition of an electron or hole to a conducting polymer chain causes the chain to distort, creating a large polaron. We show, by numerical solution of the coupled equations for the electron wave functions and the lattice displacements on a polyacetylene chain with an extra electron, that the polaron does not form in electric fields ≥6×104 V/cm. In fields ≥106 V/cm, an already formed polaron will be dissociated. Implications for current versus voltage of a light-emitting diode at high fields will be discussed. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 1867-1869 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The variation of current I with voltage V for poly(phenylene vinylene) and other polymer light-emitting diodes has been attributed to carriers tunneling into broad conduction and valence bands. In actuality the electrons and holes tunnel into polaron levels and transport is by hopping among these levels. We show that for small injection the I–V characteristic is determined mainly by the image force, for large injection by space charge effects, but in both cases the strong variation of mobility with field due to disorder plays an important role. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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