  Graphene has many advantageous properties, but its lack of an electronic band
gap makes this two dimensional material impractical for many nanoelectronic
applications, for example field effect transistors. This problem can be
circumvented by opening up a confinement induced gap, through the patterning of
graphene into ribbons having widths of a few nanometres. The electronic
properties of such ribbons depend on their size and the crystallographic
orientation of the ribbon edges. Therefore, etching processes that are able to
differentiate between the zigzag and armchair type edge terminations of
graphene are highly sought after. In this contribution we show that such an
anisotropic, dry etching reaction is possible and we use it to obtain graphene
ribbons with zigzag edges. We demonstrate that the starting positions for the
carbon removal reaction can be tailored at will with precision.
