AVS 49th International Symposium
    Electrochemistry and Fluid-Solid Interfaces Monday Sessions
       Session EC+SS-MoA

Paper EC+SS-MoA2
Studies of the Interphase Region for Liquid Hexadecane Near a Au Surface

Monday, November 4, 2002, 2:20 pm, Room C-104

Session: Liquid-Solid Interfaces & Nanoscale Electrochemistry
Presenter: A.C. Oliver, Sandia National Laboratories
Authors: A.C. Oliver, Sandia National Laboratories
J.E. Houston, Sandia National Laboratories
Correspondent: Click to Email
In this presentation, we explore the formation and properties of a solid-like"interphase" region near Au surfaces immersed in liquid hexadecane using interfacial force microscopy (IFM). We measure variations of the normal and lateral friction forces, as well as the conductance behavior, as a function of the relative interfacial separation. We show that this interphase layer passivates the normally strong bonding between two Au surfaces even at high applied stresses. In addition, no conduction is seen for this normally insulating layer until appreciable stresses are applied. By placing a voltage between tip and sample, we determine the thickness of the organized film from the behavior of the electrostatic force as a function of relative separation up to film contact. We show that at room temperature the interphase-layer thickness is ~7 molecular diameters, which increases with larger bias voltages. In addition, the lateral force shows appreciable friction before film contact for the larger voltages, indicating that the field is causing a local film organization. Data taken as a function of temperature indicates a decrease in the film organization. We discuss the implication of these results in the general context of the interaction of surface in liquid environments. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin company, for the DOE under Contract DE-AC04-94AL85000.