Force volume

TTie force-curve mapping technique is often referred to as force-volume mapping commercially, although sample volume is not probed unless stiff levers or compliant surfaces are used. 

FIGURE 2.15 Forces of interactions on blocks and nanoclay of poly[styrene-(ethylene-co-butylene)-styrene] (SEBS)-clay nanocomposite taken from force-volume experiments. (From Ganguly, A., Sarkar, M.D., and Bhowmick, A.K., J. Polym. Set, Part B Polym. Phys., 45, 52, 2006. Courtesy of Wiley InterScience.)... 

In the current work a Digital Instmments Dimension 3000 SPM was operated in force-volume mode using a probe with stiffness selected to match the stiffness of the sample. Standard silicon nitride probes with a nominal spring constant of 0.12 or 0.58 N/m were used for recombinant and native resilin samples. These samples were characterized in a PBS bath at a strain rate of 1 Hz. For synthetic rubbers, silicon probes with a nominal spring constant of 50 N/m were used and the material was characterized in air. Typically, at least three force-volume plots (16 X 16 arrays of force-displacement curves taken over a 10 X 10 p.m area) were recorded for each of the samples. 

FIGURE 9.17 A 20 X 20 jun amplitude image of the PU sample after several 16 X 16 force—volume tests in the same area. (From Huson, M.G. and Maxwell, J.M., Polym. Test., 25, 2, 2006.)... 

FIGURE 21.15 The results of force-volume measurement on NRIO sample, (a) Apparent height image, (b) reconstmcted real height image, and (c) Young s modulus distribution image. The maximum load was set to 6.0 nN. 

Practical adhesion mapping can be performed in the so-called force-volume (FV) mode. In this mode, f-d curves are acquired for each pixel. Thus, information is obtained on attractive forces before the tip contacts the surface, indentation in the contact region (see Sect. 4.3), adhesive interactions, and the dissipated energy (as area under the f-d curve, compare Fig. 4.3). 

Contact and Force Volume Mode AFM Visualization of the Morphology... 

These include contact force imaging (CFI) mode, in which the tip is scanned across the sample surface at constant force, tapping mode in which the tip oscillates close to the surface enabling either the forces or phase relationships between load and displacement to be used to form the image, and local force spectroscopy or force/volume imaging in which the variation of force with tip/sample separation at a point can be used to study local interachons. 

The onset of ferromagnetism in this system has usually been interpreted in terms of an environmental model. Fe atoms which occupy Al sites are surrounded by 8 Fe nearest neighbours and it is suggested that the percolation of such atoms (with pFc = 2.2pB) on Al sites eventually gives rise to ferromagnetism. The critical concentration does not appear to be significantly different for the two conditions. The forced volume magnetostriction peaks at 4 X 10 9 Oe-1 at 70% Fe for... 

Gaboriaud, E, Parcha, B. S., Gee, M. L., Holden, J. A., and StrugneU, R. A. 2008. SpatiaUy resolved force spectroscopy of bacterial surfaces using force-volume imaging. Colloids Surfaces B-Biointerfaces 62, 206-213. 

---