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LEED pattern taken at 140 eV after different annealing steps revealing characteristic reconstructions: (a) after degassing, (b) in coexistence with , and (c) buffer layer. (d) LEED pattern (contrast inverted) of the (00) spot of a 2 ML graphene film. The corresponding line scans still show the quasi- and (arrows) symmetry of the underlying buffer layer.
(a) Sequence of XP-spectra of the photopeak taken during the graphitization process. The peaks S1 and S2 can be attributed to and hybridized C atoms within the buffer and graphene layers. (b) From the attenuation of the SiC fraction of the peak and the peak the corresponding thickness of the layers have been calculated, as shown in the right. Normally the buffer layer is assigned as the zeroth layer. The numbers correlate with those in Fig. 1.
Sequence of EELS spectra taken after different steps of the graphitization process for (a) and (b) . The spectra (shifted for better visibility) are normalized with respect to the loss intensity at 25 eV. The losses marked by rectangles are due to single electron excitations.
Gradual blueshift of the -plasmon resonance (●) as a result of graphitization. The relative intensities of the plasmon (◻) and the Drude tails (△) increase stepwise. In order to describe the loss intensity in between the -loss and the specular reflex properly, the Drude tail was parameterized by two exponential functions. The relative integral intensities and peak positions were obtained by fitting the loss spectra of Fig. 3(a) like it is shown in the inset for the spectrum of a buffer layer.
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