  Notwithstanding numerous density functional studies on the chemically induced
transformation of multilayer graphene into a diamond-like film, a comprehensive
convincing experimental proof of such a conversion is still lacking. We show
that the fluorination of graphene sheets in Bernal (AB)-stacked bilayer
graphene (AB-BLG) grown by chemical vapor deposition on a single crystal
CuNi(111) surface triggers the formation of interlayer carbon-carbon bonds,
resulting in a fluorinated diamond monolayer (F-diamane). Induced by fluorine
chemisorption, the phase transition from AB-BLG to single layer diamond was
studied and verified by X-ray photoelectron, ultraviolet photoelectron, Raman,
UV-Vis, electron energy loss spectroscopies, transmission electron microscopy,
and DFT calculations.
