AVS 61st International Symposium & Exhibition
    Scanning Probe Microscopy Focus Topic Friday Sessions
       Session SP+AS+BI+EM+NS+SE+SS-FrM

Paper SP+AS+BI+EM+NS+SE+SS-FrM2
2013 ASSD Student Award Talk: New Insights into Nanoscale Adhesion from In Situ TEM Studies

Friday, November 14, 2014, 8:40 am, Room 312

Session: Probe-Sample Interactions and Emerging Instrument Formats
Presenter: Tevis Jacobs, University of Pennsylvania
Authors: T.D.B. Jacobs, University of Pennsylvania
J.A. Lefever, University of Pennsylvania
J. Liu, University of Wisconsin-Madison
D.S. Grierson, SysteMECH LLC
K.E. Ryan, United States Naval Academy
P.L. Keating, United States Naval Academy
J.A. Harrison, United States Naval Academy
K.T. Turner, University of Pennsylvania
R.W. Carpick, University of Pennsylvania
Correspondent: Click to Email
A fundamental understanding of adhesion is important for applications at all length scales, but is particularly critical in nanoscale devices and applications due to their high surface-to-volume ratio. Advancements in studying such tribological phenomena are typically hindered by the inaccessibility of the sliding interface. We will present nanoscale adhesion measurements conducted inside of a transmission electron microscope (TEM), using a modified in situ nanoindentation apparatus that makes contact with atomic force microscope (AFM) cantilever tips. This tool provides new opportunities to observe, identify, and quantify tribological processes with unprecedented access and resolution. First, using ultra-strong carbon-based tip materials, we find that roughness of tips can greatly reduce the pull off force and lead to severe underestimation of the work of adhesion [1]. Furthermore, we have quantified adhesion by making and breaking contact between nanoscale silicon asperities and a flat diamond substrate. The snap-in distance and the pull-off force are measured with sub-nanometer and sub-nanonewton resolution, respectively. The shape of the Si asperity is determined with sub-nanometer resolution immediately before and after contact to verify that elastic conditions were maintained. From this, we independently determine the work of adhesion and range of adhesion. The results show that accounting for roughness has a strong effect on both parameters. These two results demonstrate the importance of applying in situ approaches to studies of adhesion. --- 1. Jacobs, T.D.B., Ryan, K.E., Keating, P.L., Grierson, D.S., Lefever, J.A., Turner, K.T., Harrison, J.A. and Carpick, R.W. The Effect of Atomic-Scale Roughness on the Adhesion of Nanoscale Asperities: A Combined Simulation and Experimental Investigation. Tribol. Lett. 50, 81-93 (2013).