Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    An interpretation of the vibrational spectra of insulating and electrically conducting poly(3-methylthiophene) aided by a theoretical dynamical model (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 114-129 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: It is shown that the relevant spectral features which arise in the infrared spectrum of poly(3-methylthiophene) upon chemical doping or photoexcitation (i.e., in the electrically conducting form) can be properly explained by means of the effective conjugation coordinate (ECC) formalism. This theoretical dynamical model accounts for the intramolecular hopping of π electrons in the class of polyconjugated aromatic systems. A complete assignment for the infrared and Raman spectra of the polymer in the pristine state (i.e., in the insulating form) is proposed as the result of a theoretical vibrational potential function derived from semiempirical calculations on short oligomers. The dependence of the bandgap energy on the internal rotation about the inter-ring single bond is analyzed theoretically in dimers as model molecules and the results are compared with experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466982
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Ab initio study of torsional potentials in 2,2'-bithiophene and 3,4'- and 3,3'-dimethyl-2,2'-bithiophene as models of the backbone flexibility in polythiophene and poly(3-methylthiophene) (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 1369-1377 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Ab initio molecular orbital theory is employed to calculate the gas-phase barrier to internal rotation in 2,2'-bithiophene. Ground state geometries are fully optimized at the restricted Hartree–Fock level of theory using the 3-21G* and 6-31G** basis sets. Methylation in β-positions modulates the geometry, the inter-ring twist angle and the conformational properties of thiophene dimers. These methyl substitution effects have been assessed by calculations on the 3,4' and 3,3'-dimethyl derivatives in a number of selected conformations. A meaningful picture of the molecular relaxation on rotation is attained by allowing for full geometry optimization at both levels of calculation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467762
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Structure, polarized micro-Raman and FT-IR spectra, and ab initio calculations of 1,2-dicyanobenzene (1993)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 97 (1993), S. 10561-10569 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100143a009
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Efficient π electrons delocalization in α,α′-dimethyl end-capped oligothiophenes: A vibrational spectroscopic study (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 9271-9282 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: α,α′-dimethyl substituted oligothiophenes with increasing chain length (from the dimer up to the hexamer) were recently synthesized by chemical methods. In this paper we have investigated the vibrational Fourier transform-IR and Fourier transform-Raman spectra of solid α,α′-dimethyl substituted oligothiophenes in the neutral state. The data are consistent with the existence of a chain-length dependent π electron delocalization: a large frequency dispersion with conjugation length is observed for some Raman and infrared active vibrational modes, particularly at the high-energy side of the aromatic C=C stretching region. Vibrational assignments are proposed for the main vibrational features in the whole spectral range. This vibrational spectroscopic analysis of the solid samples thus becomes a tool for deriving information on the structure of these neutral materials in solution and in the doped state. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.471674
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Vibrational spectra of charged defects in a series of α,α′-dimethyl end-capped oligothiophenes induced by chemical doping with iodine (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 10419-10429 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present the results of a detailed study carried out on a few α,α′-dimethyl end-capped oligothiophenes which have been in situ doped with dry iodine vapors, at different concentrations. The doping process of these well sized oligomers (from dimer to hexamer) has been monitored by using Fourier transform infrared absorption and Fourier transform raman scattering spectroscopies. These data, when combined with the vibrational full assignment of the oligomers in the neutral state and the electronic absorption bands recorded for both neutral and doped compounds, provide a complete spectroscopic characterization of a full series of positive polaron-type model defects of doped polythiophene. We have also performed density functional theory quantum-chemical calculations in order to analyze the effects of ionization on the geometries and vibrational spectra of these systems. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.477697
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Lattice dynamics and vibrational spectra of pristine and doped polyconjugated polyfuran (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 769-783 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The interpretation of the infrared and Raman spectra of polyconjugated polyfuran prepared by electroreduction of 2,5-dibromofuran is presented as the result of lattice dynamical calculations. Geometries and vibrational force fields are derived from semiempirical calculations carried out on oligomers and the parameters are used for the polymer. Finally, it is shown that the infrared and Raman spectra of polyfuran pristine and doped are accounted for by effective conjugation coordinate theory, thus showing that this material also constitutes a polyconjugated material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.465077
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Analysis of the intramolecular charge transfer in donor–acceptor α,α′-substituted oligothiophenes from their vibrational spectra (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 5105-5112 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this paper we report on the vibrational Fourier transform infrared (FT–IR) and Fourier transform Raman (FT–Raman) spectra of a few donor–acceptor–substituted bi- ter-, and quaterthiophenes, as solids. The relevant vibrational information has been interpreted with the help of spectroscopic data previously collected on a model series of α,α′-dimethyl end-capped oligothiophenes, in their neutral, radical cationic, and dicationic forms. We have also performed density functional theory (DFT) quantum-mechanical calculations to analyze the effects of the intramolecular charge transfer on the geometries and vibrational spectra of these systems. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481066
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Vibrational study of a well–barrier–well thiophene–based oligomer in relation to the effective π-conjugation length (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 6907-6915 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have studied the Fourier transform infrared (FTIR) and the Fourier transform Raman (FT-Raman) spectra of a new thiophene-based oligomer in neutral form. The compound has a well–barrier–well structure, where the well parts are two bithienyl end moieties and the barrier part is a vinylene fragment with a larger energy gap. Characteristic features are correlated with vibrational data of unsubstituted α-linked oligothiophenes and α,α′-dimethyl end-capped oligothiophenes to assess information about the effective conjugation length of this oligomer. The FTIR and FT-Raman spectra have also been theoretically calculated at the B3LYP/6-31G** and RHF/6-31G** levels, respectively, to propose a vibrational assignment for the main bands in the whole spectral range. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478596
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Vibrational spectroscopic study of 5,5″-bis(dicyanomethylene)-5,5″-dihydro-Δ2,2′:5′,2″-terthiophene bearing a heteroquinonoid structure as a model of doped polythiophene (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 2543-2548 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present the results of a spectroscopic study carried out on a solid sample of 5,5″-bis(dicyanomethylene)-5,5″-dihydro-Δ2,2′:5′,2″-terthiophene. This compound bears a heteroquinonoid structure in its ground state and could be considered as a model of the structural changes induced by the different types of charge carriers in doped polythiophene. We have identified two very strong Raman bands that are indicative of the attainment of a pure heteroquinonoid structure in α-oligothienyl compounds. The large frequency downshifts of these Raman bands with respect to the pure heteroaromatic structure are a measure of the extent of the electronic modification caused by the quinoidization of the ring molecular system. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.476855
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Effect of temperature on symptom expression and accumulation of tomato spotted wilt virus in different host species (1998)
    Oxford, U.K. and Cambridge, USA : Blackwell Publishers
    Plant pathology 47 (1998), S. 0 
    Details
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The effect of two temperature regimes (daytime, 29 ± 2°C, night-time, 24 ± 3°C; and daytime, 23 ± 1°C, night-time, 18 ± 2°C) on the symptoms caused by tomato spotted wilt virus (TSWV), and the accumulation of TSWV virions, was compared in Datura stramonium, Nicotiana tabacum cv. White Burley and Physalis ixocarpa. Tobacco plants were more severely affected by TSWV at the high temperature regime, but the incidence (percent of plants with symptoms) was 100% for both regimes. In P. ixocarpa and D. stramonium the higher temperature caused an increase in both incidence and rate of development of symptoms. At high temperature, all three species showed both local and systemic symptoms; however, at low temperature only P. ixocarpa consistently developed systemic symptoms. In general, virus accumulation in the inoculated leaves (presumably the combined effect of virus replication and local movement) of all plants was higher at the lower temperature. Long distance movement in tobacco, leading to virion accumulation in other plant organs, was favoured by high temperature; but there was relatively little effect in P. ixocarpa and D. stramonium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3059.1998.00249.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...