  Quasi-free standing epitaxial graphene is obtained on SiC(0001) by hydrogen
intercalation. The hydrogen moves between the 6root3 reconstructed initial
carbon layer and the SiC substrate. The topmost Si atoms which for epitaxial
graphene are covalently bound to this buffer layer, are now saturated by
hydrogen bonds. The buffer layer is turned into a quasi-free standing graphene
monolayer with its typical linear pi-bands. Similarly, epitaxial monolayer
graphene turns into a decoupled bilayer. The intercalation is stable in air and
can be reversed by annealing to around 900 degrees Celsius.
