Electrostatic interactions between graphene layers and their environment

We analyze the electrostatic interactions between a single graphene layer and a SiO2 substrate, and other materials which may exist in its environment. We obtain that the leading effects arise from the polar modes at the SiO2 surface, and water molecules, which may form layers between the graphene sheet and the substrate. The strength of the interactions implies that graphene is pinned to the substrate at distances greater than a few lattice spacings. The implications for graphene nanoelectromechanical systems, and for the interaction between graphene and a scanning tunneling microscopy tip, are also considered.