AVS 46th International Symposium
    Nanometer-scale Science and Technology Division Monday Sessions
       Session NS1-MoA

Paper NS1-MoA9
Combined Quartz Crystal Microbalance and Scanning Probe Microscope Studies of Vapor-Deposited Films on Metal Surfaces

Monday, October 25, 1999, 4:40 pm, Room 612

Session: Nanoscale Tribology and Adhesion
Presenter: B. Borovsky, North Carolina State University
Authors: B. Borovsky, North Carolina State University
M. Abdelmaksoud, North Carolina State University
J. Krim, North Carolina State University
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Experimental investigations of friction, lubrication and adhesion at nanometer lengthscales have traditionally been performed by employing force microscopy, surface forces apparatus (SFA), or quartz crystal microbalance (QCM) techniques. While collectively these techniques have yielded much useful information, their results have to date never been mutually cross-referenced. In order to achieve such a cross referencing, we have performed two sets of measurements: (1) A QCM study of the system toluene/Ag(111) with and without C@sub 60@ vapor-deposited on the Ag(111) surface, and (2) a joint QCM/SPM study of the systems Ethylene/Pt and Oxygen/Ag. The former system has been studied by means of SFA,@footnote 1@ whereby it was reported that C@sub 60@ at a toluene/mica surface resulted in a significant reduction in friction levels. The latter studies allow direct comparison of SPM and QCM data, as the measurements are carried out in unison. Our studies of toluene/C@sub 60@ have revealed that the decrease in friction reported in Ref. 1 is most likely due to the manner in which the C@sub 60@ layer adheres to the solid substrate. Meanwhile, we have observed that for ethylene and oxygen adsorbed on Ag, a measurable shift in the frequency and amplitude response of the QCM occurs as the STM tip is dragged through the adsorbed layers. Additionally, allowing rubbing to proceed for extended periods within a small scanned region produces a large contrast with the surrounding region in STM images. The experiment is currently being repeated on a Pt substrate in order to search for a tribochemically-triggered reaction. Work funded by AFOSR F49620-98-1-02-1 and NSF DMR9896280 @FootnoteText@ @footnote 1@ S.E. Campbell, G. Luengo, V.I. Srdanov, F. Wudl and J.I. Israelachvili, Nature, volume 82, p 520 (1996) .