▎ 摘　　要

We employed nanometer-scale spatially resolved electron energy loss spectroscopy to monitor the degree and localization of electronic passivation of graphene surfaces by using the pi-plasmon as an indicator of sp(2)-bonding. Upon hydrogenation, the pi-plasmon does not vanish, and a new feature at 7 eV occurs in the spectra. This behavior conforms to the theoretical electron energy loss spectra derived from density functional calculations for partial hydrogenation, with benzene rings assuming a corrugated structure. The spatial distribution of the spectral features and atomic resolution Z-contrast images indicate absence of any long-range ordering in the hydrogenated areas. (C) 2010 American Institute of Physics. [doi:10.1063/1.3526373]