title: Dynamic shear force microscopy of viscosity in nanometer-confined hexadecane layers.
abstract: Hexadecane exhibits pronounced molecular layering upon confinement to gaps of a few nanometer width which is discussed for its role in boundary lubrication. We have probed the mechanical properties of the confined layers with the help of an atomic force microscope, by quasi-static normal force measurements and by analyzing the lateral tip motion of a magnetically actuated torsional cantilever oscillation. The molecular layering is modeled by a oscillatory force curve and the tip approach is simulated assuming thermal equilibrium correlations in the liquid. The shear response of the confined layers reveals gradually increasing stiffness and viscous dissipation for a decreasing number of confined layers.
authors.affiliation: INM-Leibniz Institute for New Materials and Physics Department, Saarland University, Campus D2 2, 66123 Saarbrücken, Germany.
authors.forename: Marc-Dominik
authors.initials: MD
authors.lastname: Krass
authors.forename: Nitya Nand
authors.initials: NN
authors.lastname: Gosvami
authors.forename: Robert W
authors.initials: RW
authors.lastname: Carpick
authors.forename: Martin H
authors.initials: MH
authors.lastname: Müser
authors.forename: Roland
authors.initials: R
authors.lastname: Bennewitz