Local force spectroscopy

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. 

More subtle effects of the dielectric constant and the applied bias can be found in the case of semiconductors and low-dimensionality systems, such as quantum wires and dots. For example, band bending due to the applied electric field can give rise to accumulation and depletion layers that change locally the electrostatic force. This force spectroscopy character has been shown by Gekhtman et al. in the case of Bi wires [38]. 

Dynamic force spectroscopy (DFS) was introduced [1] allowing us to understand quantitatively dissipative and non-dissipative processes in dynamic force microscopy [2]. Using a combined experimental and computer simulation technique it is possible to reconstruct force/distance ciuves without using any model potentials and parameters. This method opens the perspective to extract material parameters such as atomic densities of the surface investigated as well as local elastic properties... 

A relatively new TA technique, known as micro-thermal analysis (/r-TA) can be considered as a coupled TA technique since usually two or more measurements are made simultaneously. /r-TA combines the imaging capabilities of atomic force spectroscopy with a form of localized TA, and this technique offers nanotechnological TA applications. 

Nuclear magnetic resonance (NMR) spectroscopy is an important method for materials characterisation and for the study of polymer structure-property relationships. The importance of NMR as a technique arises in part because the signals can be assigned to specific atoms along the polymer backbone and side chains [1,2]. The properties of the NMR signals depend on the magnetic environment of the NMR active nuclei, and the local fields that they experience. Since the NMR spectrum is determined by local forces, this method provides valuable and unique information about polymers on an atomic-length scale. 

Thermal analysis using heated tip technology [115] has been reviewed by Price et al. [116], Wunderlich [117], Pollock and Hammiche [118], and Abad et al. [119]. Reviews on mechanical deformation of polymer films by nanoindentation [120] and AFM indentation [121] as well as in situ tensile deformation [122] have been published. A related area of force spectroscopy to extract intermolecular and intramolecular forces between polymer chains was reviewed by Hugel and Seitz in 2001 [123]. Bushan has written extensively on the use of SPM to study tribology [124], and frictional contrast has been discussed in reviews by Mate [125], Zasadzinski [126], and Feldman et al. [127]. Spatially localized adhesion studies using chemically modified AFM tips was reviewed in 2005 by Vezenov et al. [128] and Vancso et al. [129]. Characterization of polymer film surfaces [130,131], latexes [132,133], multiphase polymer blends [134, 135], and nanocomposites [136, 137] has also been reviewed. Authors from the laboratories of several manufacturers of industrial engineering polymers have published reviews on the application of SPM to characterization [138-140]. 

In this paper it has been shown that IR spectroscopy remains one of the most incisive tools for the study of both strong and weak bonding at surfaces. In addition to being able to study surface species structure in the chemisorbed layer, it is possible to obtain dynamical information about more weakly-bound adsorbates as they llbrate and rotate on the surface. These motions are controlled by local electrostatic forces due to polar surface groups on the surface. 

Anderson, M. S. (2000) Locally enhanced Raman spectroscopy with an atomic force microscope. Appl. Phys. Lett., 76, 3130-3132. 

Burns, A. R., Frankel, D. J. and Buranda, T. (2005) Local mobility in hpid domains of supported bilayers characterized by atomic force microscopy and fluorescence correlation spectroscopy. Biophys. J., 89, 1081-1093. 

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