C1sXPS spectra of graphitic carbon on MgF2. The dashed line is a fit with four Lorentzian functions. The two strongest peaks (centered at 284.6 eV (red) and 285.8 eV (green)) are assigned to sp2 and sp3 hybridized carbon atoms, respectively. The fraction of the sp2 bond is estimated to be 80.1%.
Jerng et al. Nanoscale Research Letters 2013 8:11 doi:10.1186/1556-276X-8-11