Polaron Excitations in Fullerenes : Theory as π-Conjugated Systems

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概要

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• We review the recent theoretical treatment of fullerenes as π-conjugated systems. Polaronic properties due to the Jahn-Teller type effects are mainly discussed. (1) A Su-Schrieffer-Heeger type electron-phonon model is applied to fullerenes: C_<60> and C_<70>, and is solved within the adiabatic approximation applied to the phonons. When the system (C_<60> or C_<70>) is doped with one or two electrons (or holes), the additional charges accumulate at twenty carbons almost along an equatorial line of the molecule. The dimerization becomes the weakest along the same line. Two energy levels, the occupied state and the empty state, intrude largely in the gap. The intrusion is larger in C_<70> than in C_<60>. These are "polarons" in doped fullerenes. It is also found that C_<60> and C_<70> are related mutually with respect to electronical structures as well as lattice geometries. (2) We apply the model to the fullerene epoxide C_<60>O. It has the polaron-type lattice distortion around the oxygen, and also shows the energy level intrusion in the gap. (3) Optical properties of C_<60> are calculated and discussed In the absorption of the doped molecule, a new peak structure is present owing to the polaronic distortion. In the luminescence of the neutral C_<60>, the spacing between H_g(8)-phonon side-band peaks and the relative intensities agree well with experiments. In the dispersion of the third hamonic generation, the magnitudes of |χ^<(3)>| agree with those of experiments at the resonance of the lowest allowed transition as well as in the region away from the resonance.

• 理論物理学刊行会の論文
• 1993-10-20

著者

• Harigaya Kikuo

  Fundamental Physics Section Physical Science Division Electrotechnical Laboratory

• Harigaya Kikuo

  Fundamental Physics Section Electrotechnical Laboratory

• Harigaya K

  Aist Tsukuba

• HARIGAYA Kikuo

  Fundamental Physics Section, Physical Science Division Electrotechnical Laboratory

関連論文

• Dispersion of the Third-Order Nonlinear Optical Susceptibility in C_60 Calculated with a Tight-Binding Model
• Polaron Excitations in Fullerenes : Theory as π-Conjugated Systems
• Optical Absorption Spectra of A_6C_ : Reduction of Effective Coulomb Interactions
• Optical Absorption in Higher Fullerenes : Effects of Symmetry Reduction
• Lattice and Electronic Structures of Undoped and Doped C_ Molecules by the Extended Su-Schrieffer-Heeger Model

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