Hydrogen adsorption on single-walled carbon nanotubes studied by core-level photoelectron spectroscopy and Raman spectroscopy

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 carbon nanotube using synchrotron-radiation-based core-level photoelectron spectroscopy and Raman spectroscopy. From C1s spectra, we identified a peak component due to CH bonds of carbon atoms in single-walled carbon nanotubes. We also found the suppression of -plasmon excitation, indicating that the hydrogen adsorption deforms the bonding structure. Raman spectra of the single-walled carbon nanotubes indicated that the radial-breathing-mode intensities decreased due to the adsorption-induced bonding-structure deformation. Moreover, the decrease for single-walled carbon nanotubes with small-diameter was more severe than that for large-diameter. Our results strongly suggest that the hydrogen adsorption, which induces the structure deformation from sp to sp bonding, depends on the diameter of SWCNTs.