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To: Andrew Vance who wrote (14335)6/9/1998 10:09:00 AM
From: Trader X  Respond to of 17305
 
+ 2. Direct and Controlled Manipulation of Nanometer-Sized Particles Using the Non-Contact Atomic Force Microscope

Abstract

In this paper, we present techniques for the direct and controlled manipulation of nanoscale three-dimensional (3D) features using the non-contact atomic force microscope (NC-AFM). A systematic examination of the nature of NC-AFM images of such 3D features leads us to propose two distinct protocols for nanomanipulation. The first protocol consists of switching off the NC-AFM feedback loop just as the tip approaches a nanofeature of interest. This results in tip-nanofeature contact and causes the feature to be "pushed" along the surface as the tip continues to move laterally. The second protocol exploits a peculiar feature of the NC-AFM which produces reversal of contrast of nanofeatures from positive to negative in NC-AFM images, due to a feedback instability. The contrast reversal, which is likely to be universal to NC-AFM, occurs with changes in imaging conditions and potentially leads to tip-sample contact, thereby allowing manipulation. This second technique has the advantage of easier identification of the manipulation regime and the potential for manipulating features that are only a few nm in size. We demonstrate the viability of these two protocols by directly manipulating gold
particles of diameters 5 and 15 nm into pre-determined patterns on a mica surface. We also illustrate a simple, generic approach that is useful for obtaining detailed information on the mechanism of any
manipulation based on the scanning probe microscope.

foresight.org