Graphene and its chemical derivatives

The strictly two dimensional material called graphene was presumed not to exist in the free state until only a few years ago. The most amazing things about graphene probably is that its electrons move with little scattering over huge (submicron) distances as if they were completely insensitive to the environment only a couple of angstroms away. Moreover, whereas electronic properties of other materials are commonly described by quasiparticles that obey the Schrodinger equation, electron transport in graphene is different: It is governed by the Dirac equation so that charge carriers in graphene mimic relativistic particles with zero rest mass. Graphene opens a new direction of research: quasi-relativistic experiments in condensed-matter set-up. Another way of looking at graphene is to think of it as a giant molecule with a possibility of altering it by chemical means. To this end, we have found that can react with atomic hydrogen, which transforms this zero-overlap semimetal into an insulator. Transmission electron microscopy reveals that the obtained graphene derivative (graphane) is crystalline and retains the hexagonal. The reaction with hydrogen is reversible, so that the original metallic state, the lattice spacing and even the quantum Hall effect can be restored by annealing. This illustrates the concept of graphene as a robust atomic-scale scaffold, on the basis of which new two-dimensional crystals with designed electronic properties can be created by attaching other atoms and molecules.