title: Solvation force simulations in atomic force microscopy.
abstract: Solvation force oscillation in octamethylcyclotetrasiloxane (OMCTS) versus the distance between an atomic force microscope (AFM) tip and mica substrate has been studied through molecular dynamics simulations. A driving spring model in a liquid-vapor molecular ensemble is used to explore the force oscillation mechanism. It has been found that OMCTS fluid in tip-substrate contact has a strong tendency to form a layered structure, starting from n = 8 layers. The force profile obtained from simulation is qualitatively similar to those in contact mode AFM experiments. However, the bulk-like diffusion and rotation of OMCTS molecules underneath the AFM tip suggest that, under the tip-substrate confinement geometry, the layered OMCTS film cannot form a solidified structure except under n = 2 extreme contact-layer confinement.
authors.affiliation: Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC 20052, USA.
authors.forename: Rong-Guang
authors.initials: RG
authors.lastname: Xu
authors.affiliation: Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC 20052, USA.
authors.forename: Yongsheng
authors.initials: Y
authors.lastname: Leng