Ripple morphology of graphitic surfaces: a comparison between few-layer graphene and HOPG

摘要: The surface structure of Few-Layer Graphene (FLG) epitaxially grown on the C-face SiC has been investigated by TM-AFM in ambient air and upon interaction with diluted aqueous solutions bio-organic molecules (dimethyl sulfoxide, DMSO, L-Methionine). On pristine FLG we observe nicely ordered, three-fold oriented rippled domains, a 4.7+/-0.2 nm periodicity (small periodicity, SP) peak-to-valley distance range 0.1-0.2 nm. Upon mild molecular solution, ripple relaxes to 6.2+/-0.2 (large LP), while height increases 0.2-0.3 When additional energy is transferred system through sonication graphene planes are peeled off from FLG, as shown quantitative analysis XPS Raman spectroscopy data which indicate neat reduction thickness. domains no longer observed. Regarding HOPG, could not ripples cleaved samples air, LP develop solutions. Recent literature similar systems univocal regarding interpretation rippling. complex our comparative observations HOPG can be hardly rationalized solely base assembly molecules, either organic coming solution or adventitious species. We propose consider manifestation free-energy minimization quasi-2D layers, eventually affected factors such interplane stacking, and/or AFM tip.