Figure 2: Graphene etching on high-temperature and atomic H dose.
From: Graphene etching on SiC grains as a path to interstellar polycyclic aromatic hydrocarbons formation
(a) STM image (5 × 5 nm2) showing a graphene region V=100 mV; the small mesh corresponds to the atomic honeycomb atomic lattice of graphene. (b) The image shows at the upper side a graphene plane, whereas at lower part the surface has strongly roughened. 40 × 40 nm2 V=−100 mV. (c) Profile on STM images recorded before (blue) and after (black) being exposed to atomic H with the surface kept at 1,200 K, taken along the dotted line indicated in. The total roughness (r.m.s.) of the surface increases from 0.22 to 0.69 Å. (b,d–f) Series of STM images showing the graphene surface eroded after atomic H exposure at high temperature. (d) STM image (10 × 10 nm2) recorded on the most eroded part that shows the formation on the surface of small molecules and nanostructures. V=−200 mV (f) STM image (2.2 × 4 nm2) zooming in on a detail of the surface showing protrusions corresponding to localized molecular orbitals of a PAH-like molecule. (e) Overlaid optimized DFT model of a proposed PAH formed.
