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Yukio Furukawa

Other affiliations: University of Tokyo, Tohoku University, Osaka City University  ...read more
Bio: Yukio Furukawa is an academic researcher from Waseda University. The author has contributed to research in topics: Raman spectroscopy & Infrared spectroscopy. The author has an hindex of 35, co-authored 117 publications receiving 4896 citations. Previous affiliations of Yukio Furukawa include University of Tokyo & Tohoku University.


Papers
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591 citations

Journal ArticleDOI
TL;DR: In this article, the infrared and Raman spectra of neutral polythiophene were analyzed on the basis of the data of oligomers (α-bithiophene, α-terthiophen, β-quaterthiopane, and α-sexithiophenes) and deuterated and 2,5-13C-substituted polythyphenes.

317 citations

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TL;DR: In this article, it was shown that polarons are the major species generated by doping in most non-degenerate conjugated polymers such as polythiophene, poly(p-phenylene), and poly(polyphenylenevinylene).
Abstract: Conjugated conducting polymers constitute a subject of research lying at the interface between solid-state physics and molecular science. Electronic absorption and vibrational spectroscopies of doped conjugated polymers, whose ground states are nondegenerate, are reviewed from a viewpoint of molecular spectroscopy. Raman spectroscopy is a powerful tool for studying the structures of polarons and bipolarons, which are associated with electrical, magnetic, and optical properties of the polymers. Electronic absorption and Raman spectra of doped polymers have been analyzed on the basis of those of model compounds. These analyses have led us to the conclusion that polarons are the major species generated by doping in most nondegenerate conjugated polymers such as polythiophene, poly(p-phenylene), and poly(p-phenylenevinylene), in contrast with the previous view that bipolarons are the major species. The theoretical and experimental bases of these two contradictory views are discussed.

284 citations

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TL;DR: In this article, the structural details of doped polyacetylene (a highly conducting organic polymer) were studied using optical absorption, Raman, and infrared spectra of polyacetylenes.
Abstract: In order to elucidate the structural details of doped polyacetylene (a highly conducting organic polymer), the optical absorption, Raman, and infrared spectra of not only trans‐(CH)x doped with iodine, AsF5, and SO3 but also β‐carotene doped with iodine and SO3 were studied. The infrared spectra of two kinds of isotopically substituted polyacetylenes (CD)x and (13CH)x doped with iodine were also observed. Analysis of the experimental results shows that upon doping each of the four vibrational branches (ν1–ν4) in the 1600–900 cm−1 region of a polyene chain splits into two groups, namely, the higher frequency group and the lower frequency one. The former group consists of the ’’gerade’’ vibrations of polyene parts which are not directly attacked by dopants but are perturbed along the chain, whereas the latter is made up of the ’’ungerade’’ vibrations of the positively charged polyene part with the doped site at its center. The Raman bands in the higher‐frequency group of ν1 (mainly the C=C stretching mode) ...

278 citations


Cited by
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TL;DR: It is shown how to use resonant Raman spectroscopy to determine structure and composition of carbon films with and without nitrogen, and the assignment of the peaks at 1150 and 1480 cm−1 often observed in nanodiamond.
Abstract: Raman spectroscopy is a standard characterization technique for any carbon system. Here we review the Raman spectra of amorphous, nanostructured, diamond-like carbon and nanodiamond. We show how to use resonant Raman spectroscopy to determine structure and composition of carbon films with and without nitrogen. The measured spectra change with varying excitation energy. By visible and ultraviolet excitation measurements, the G peak dispersion can be derived and correlated with key parameters, such as density, sp(3) content, elastic constants and chemical composition. We then discuss the assignment of the peaks at 1150 and 1480 cm(-1) often observed in nanodiamond. We review the resonant Raman, isotope substitution and annealing experiments, which lead to the assignment of these peaks to trans-polyacetylene.

2,172 citations

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TL;DR: In this paper, the emeraldine oxidation state of polyaniline was converted from an insulator to a metal by treatment with 1M aqueous HCl to form the corresponding salt, emeraldines hydrochloride.

1,286 citations

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TL;DR: The ETS-NOCV scheme offers a compact, qualitative, and quantitative picture of the chemical bond formation within one common theoretical framework and can be widely used for the description of different types of chemical bonds.
Abstract: In the present study we have introduced a new scheme for chemical bond analysis by combining the Extended Transition State (ETS) method [Theor. Chim. Acta 1977, 46, 1] with the Natural Orbitals for Chemical Valence (NOCV) theory [J. Phys. Chem. A 2008, 112, 1933; J. Mol. Model. 2007, 13, 347]. The ETS-NOCV charge and energy decomposition scheme based on the Kohn−Sham approach makes it not only possible to decompose the deformation density, Δρ, into the different components (such as σ, π, δ, etc.) of the chemical bond, but it also provides the corresponding energy contributions to the total bond energy. Thus, the ETS-NOCV scheme offers a compact, qualitative, and quantitative picture of the chemical bond formation within one common theoretical framework. Although, the ETS-NOCV approach contains a certain arbitrariness in the definition of the molecular subsystems that constitute the whole molecule, it can be widely used for the description of different types of chemical bonds. The applicability of the ETS-...

1,193 citations

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TL;DR: A survey of the literature available on conducting organic polyaniline can be found in this paper, where the authors provide a survey of some of the most recent work on polyanILine.

1,029 citations