title: van der Waals screening by single-layer graphene and molybdenum disulfide.
abstract: A sharp tip of atomic force microscope is employed to probe van der Waals forces of a silicon oxide substrate with adhered graphene. Experimental results obtained in the range of distances from 3 to 20 nm indicate that single-, double-, and triple-layer graphenes screen the van der Waals forces of the substrate. Fluorination of graphene, which makes it electrically insulating, lifts the screening in the single-layer graphene. The van der Waals force from graphene determined per layer decreases with the number of layers. In addition, increased hole doping of graphene increases the force. Finally, we also demonstrate screening of the van der Waals forces of the silicon oxide substrate by single- and double-layer molybdenum disulfide.
authors.affiliation: Chemistry Division, ‡Electronic Science and Technology Division, and §Materials Division, US Naval Research Laboratory , Washington, D.C. 20375, United States.
authors.forename: Stanislav
authors.initials: S
authors.lastname: Tsoi
authors.forename: Pratibha
authors.initials: P
authors.lastname: Dev
authors.forename: Adam L
authors.initials: AL
authors.lastname: Friedman
authors.forename: Rory
authors.initials: R
authors.lastname: Stine
authors.forename: Jeremy T
authors.initials: JT
authors.lastname: Robinson
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Reinecke
authors.forename: Paul E
authors.initials: PE
authors.lastname: Sheehan
keywords: atomic force microscopy; graphene; screening; van der Waals interactions