Impurity atoms in graphene can be detected using atomic force microscopy, according to a study conducted on April 13, 2018.
Physicists at the University of Basel were successful in using atomic force microscopy to obtain images of individual impurity atoms in graphene ribbons. A two-dimensional layer of carbon atoms arranged in a hexagonal lattice forms graphene. Graphene is stable and flexible, as the bonds between the carbon atoms are strong. Also, graphene is a good conductor of electricity.
By adding impurity atoms through process of doping, distinctive properties of graphene can be expanded. The researchers specifically created and examined graphene ribbons containing impurity atoms by collaborating with scientists from the University of Basel and the National Institute for Material Science in Tsukuba in Japan. Using surface chemistry, specific atoms in the lattice were replaced with boron and nitrogen and organic precursor compounds were placed on a gold surface. Tiny graphene ribbons, when exposed to 400°C, were formed on the gold surface from the precursors. Further, the graphene ribbons were analyzed with the help of atomic force microscopy. They used a carbon monoxide functionalized tip and measured the tiny forces that act between the tip and the individual atoms.
The smallest differences in forces can also be detected using this method. Atoms were identified by analyzing the different forces. Dr. Shigeki Kawai, lead author of the study said, “The forces measured for nitrogen atoms are greater than for a carbon atom. We measured the smallest forces for the boron atoms.” The readings were confirmed using computer simulations and this proved that AFM technology is well-suited for conducting chemical analyses of impurity atoms in the promising two-dimensional carbon compounds.