(a) Models of fluorinated graphene with C2F composition. Left: Alternating zigzag chains of fluorinated carbon and bare carbon. Middle: Alternating armchair chains of fluorinated carbon and bare carbon. Right: Alternating double carbon bonds and CF–CF bonds. White spheres represent the bare carbon atoms; the change in color within the fluorinated unit indicates change of position (up or down) of fluorine atoms relative to the graphene sheet. (b) Fragments of fluorinated graphene with zigzag chain (model 1), armchair chain (model 2), and double bond (model 3) fluorine pattern, calculated at the B3LYP/6-31G level. The central atoms, which were replaced by nitrogen atoms to calculate the C95F42N+ structures, are marked. (c) Comparison of experimental NEXAFS CK edge spectrum of the fluorinated HOPG with theoretical spectra of the models 1, 2, and 3. The components of the theoretical spectrum correspond to a contribution from a bare carbon atom (orange line) and fluorinated carbon atom (violet line).
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