▎ 摘　　要

By means of high resolution atomic-force microscopy (AFM) we investigated the surface of graphene and graphite. Our study shows that if the samples were stored in ambient laboratory conditions, an adsorbate of airborne contaminants, presumably hydrocarbons, forms well-ordered layer over the whole area of graphene flakes. In general case, this layer has a stripe structure of 4-5 nm pitch with domains differing in the direction of the stripes. The size of one domain can exceed 100 mu m(2), which means that almost the entire area of a graphene flake can be under a layer with a constant stripe direction. By mechanical impact of AFM probe, we can turn the direction of the stripe structure, while its pitch is preserved. Visualization of the self-assembled structure may be hampered by the presence of non-ordered overlayer. (C) 2018 Elsevier Ltd. All rights reserved.