Mimicking an Atomically Thin 'Vacuum Spacer' to Measure the Hamaker Constant between Graphene Oxide and Silica

The Hamaker constant between graphene oxide and silica, which quantifies the strength of van der Waals forces is determined, by mimicking a “vacuum spacer” in an atomic force microscopyforce study. It is demonstrated that, a 2D spacer is expected to yield an accurately defined separation, owing to the high atom density and strength in planar direction compared with other dimensional spacers.