総説

光電子分光からみた低次元フラーレンポリマーの
構造と電子物性

Structural and Electronic Properties of Low-dimensional C60 Polymers
Studied by Photoelectron Spectroscopy

尾上 　順
Jun ONOE

光電子分光からみた光重合および電子線重合によって生成したフラーレンポリマーの低次元構造と電子物性を筆者らの研究成果を中心に紹介した。光重合ポリマーでは、２次元hexagonal ダンベル型構造を有し半導体的特性を示すのに対して、電子重合ポリマーでは、負のガウス曲率をもつ新しい擬１次元ピーナッツ型構造を有し金属的特性を示すことを明らかにした 。

When a C₆₀ film was irradiated with UV-visible light and electron-beam under a ultrahigh vacuum condition, photo-induced polymerization and electron-induced polymerization between adjacent C₆₀ molecules take place via [2+2] dumbbell-shaped and peanut-shaped cross-linkages, respectively. We have investigated the electronic structure of both dumbbell-shaped and peanut-shaped C₆₀ polymers, using in situ X-ray and ultraviolet photoelectron spectroscopy, and found that the dumbbell-shaped C₆₀ polymer has a two-dimensional hexagonal structure, while that the peanut-shaped C₆₀ polymer has a quasi-one-dimensional structure. In the present paper, we review the photoelectron spectroscopic results of these low-dimensional C₆₀ polymers, together with results of their structural and electronic properties obtained using other measurements and density-functional calculations. Finally, we will describe the perspective of both dumbbell- and peanut-shaped C₆₀ polymers. In particular, the latter polymer is interesting to be a π-electron conjugated system with negative Gauss curvature.

Keywords: in situ x-ray and ultraviolet photoelectron spectroscopy, Photo-induced polymerization, Electron-beam induced polymerization, Dumbbell-shaped C₆₀ polymers, Peanut-shaped C₆₀ polymer, Negative Gauss curvature, Electronic structure, Electron-transport properties, topology