A tungsten needle was successfully removed visible in an electron microscope pollution molecular scale with the surface of the graphene sheet. Thus physics has reached the maximum possible surface cleaning kind of nanofabric, however, having studied the processes of contamination visually cleaned of layers, they confirmed the presence of mobile molecules, invisible under the electron microscope. Thus, they denied the possibility of absolute purity two-dimensional material on a molecular scale. Article published in the journal Nature Communications.
Purity control plays an important role in any scientific experiment and technological process. With the advent of two-dimensional materials, the notion of purity has to be revised, for example, in graphene the presence of even a single added atom leads to significant changes of properties or even to destruction, and however complicated the description of thin layers or obtaining new structures on the surface. Pollution waiting for the surface at every moment when receiving, handling and storage, but are still cleaning methods that are able to selectively clean the surface with a precision of molecules does not exist. Existing methods of cleaning involve a message to the surface to be cleaned of any energy, which substances are sensitive. In the past scientists have tried to use an atomic force microscope, but to achieve the purity of graphene at the molecular level, they have failed.
Peter Schweizer (Peter Schweizer) and his colleagues used a tungsten needle with a thickness of 50-150 nanometers as a bilateral manipulator for cleaning of surface contamination on the graphene sheet. After the processes of mechanical cleaning, they investigated the mechanism of contamination of the surface due to surface diffusion.