Graphene on ultraflat substrates such as hexagonal boron nitride has shown to suppress charge puddle formation and give high carrier mobility [1,2]. Transfer of graphene to other ultraflat substrates such as muscovite mica might bring about similar transport characteristics. To that end, we place graphene on mica for scanning tunneling microscopy (STM) studies. We grow monolayer graphene on Cu by chemical vapor deposition and support it with polymethyl methylacrylate (PMMA). We clean the film with water baths and transfer it to mica. In contrast to previous atomic force microscopy (AFM) experiments of dry-transferred exfoliated graphene on mica [3,4], our graphene films trap multiple water layers. After a 700 ºC in situ degas, we achieve atomic resolution of graphene on water on mica, and we notice that there are at least 3 layers of ordered, bound water on mica [5], due to the wet transfer and the highly hydrophilic mica. We can atomically image graphene monolayers, bilayers, and grain boundaries regardless of the underlying water structure. Additional water layers on top of the bound water are rough, weakly bound, and amorphous. We notice up to 5 layers of graphene-encapsulated water on mica. Using the STM tip, we can nanomanipulate these amorphous layers at high tunneling conditions (>6 V, 1 nA). These water patterns are highly stable, invariant after several days of scanning. Water nanomanipulation under graphene could help elucidate water’s complex bonding structure and charge transfer from graphene to encapsulated species. Further, graphene-coated water can assist in STM-based research of other aqueous-suspended nanostructures.

[1] Xue et al., Nature Mat. 10, 282 (2011); [2] Dean et al., Nature Nano. 5, 722 (2010); [3] Xu et al., Science 329, 1188 (2010); [4] Lui et al., Nature 462, 339 (2009); [5] Park et al., Phys. Rev. Lett. 89, 85501 (2002).