Diameter dependence of hydrogen adsorption on single-walled carbon nanotubes

Tokura, Akio*; Maeda, Fumihiko*; Teraoka, Yuden; Yoshigoe, Akitaka ; Takagi, Daisuke*; Homma, Yoshikazu*; Watanabe, Yoshio*; Kobayashi, Yoshihiro*

We have investigated the adsorption of atomic hydrogen on vertically aligned SWNT film. The effects of hydrogen adsorption were investigated by photoelectron spectroscopy and Raman spectroscopy. By fitting C 1s core level spectrum, we found the component attributed to hydrogenation of carbon. The suppression of plasmons was also found. These results indicate that hydrogen adsorption induced bonding structure deformation. Raman spectra demonstrate that the radial-breathing-mode intensity of small-diameter SWNTs is more severely decreased than that of large-diameter SWNTs. The G-band/D-band ratio also decreased after the irradiation. These results indicate the disordering of graphene on small-diameter SWNTs is induced more easily. Our results indicate that the adsorption coefficient of hydrogen atoms for SWNTs with small diameter is higher than that for SWNTs with large diameter.