Force-Distance Curve Conversion

To convert the force-distance curve data to a relation that can be applied to the contact mechanics model, the following procedure is typically used. One can obtain the load P by Hooke s law, 

Using Equation 17.9, one can obtain the work of adhesion from the pull-off force 

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Inverted CFM. The functionalized AFM tip was placed in the liquid cell. After a brief equilibration period in ultrapure water the tip was engaged on an octadecanethiol SAM on Au(lll) and a set of force-distance curves was recorded. After withdrawal of the tip the cell was flushed with more than 20 times the cell volume of aqueous NaOH. After a stable photodiode reading the tip was engaged again on the octadecanethiol SAM. Immediately after engaging force-distance curves were recorded in intervals of 30 (60) seconds. The mean of 10 individual pull-off events, measured after each 30 seconds (60 seconds for slow reactions), was calculated. The conversion x, of ester groups to hydroxyl groups was calculated from ... 

Figure 1 Schematic illustration of single-molecule force-distance measurement of a supramolecular host-guest pair exploiting a surface-attached single-polymer chain. The conversion of the recorded cantilever deflection-piezo displacement signal (a) into a force-extension curve of the single-polymer chain (b) is shown. (Redrawn from Ref. 21. Wiley-VCH, 2006.)...

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