Characterisation techniques atomic force microscopy

To understand the principles at which biological systems operate, detailed studies on ultrastructure, material properties, force range, and motion pattern during locomotion are necessary. Such studies have become possible in the past several years due to new developments (1) in microscopical visualization techniques (atomic force microscopy, freezing and environmental scanning electron microscopy), (2) in characterisation of mechanical properties of biological materials and structures in situ and in vivo (measurements of stiffness, hardness, adhesion, friction) at local and global scales, and (3) in computer simulations. 

So far, few authors [7,8] have reported X-ray reflectivity data for nitrides. This technique offers a very precise method of measuring the thickness of layers thinner than about 2000 A and their roughness. With a growing number of nitride samples of a very small roughness, reflectivity will soon become a commonly used characterisation technique. However, one should be aware that the level of surface roughness obtained from reflectivity often does not coincide with the data of atomic force microscopy (AFM) or even optical microscopy. This is because each technique has a different length scale and studies using complementary methods are necessary to obtain a real model of the surface. 

Like all types of polymers, conductive polymers are first characterised by spectroscopic techniques, and this is of particular importance for nanostructured materials too. Atomic force microscopy (AFM) is a powerful (and relatively inexpensive) microscopic technique for surface studies at nanoscale, and sometimes this is essential for the investigation of conductive polymers. Despite available limitations, progress in nanodevices has provided... 

The development of nanostructured conductive polymers also requires the development of advanced characterisation techniques, and this aspect of current research is captured in several chapters. A detailed review of Atomic Force Microscopy (AFM) covers the wide range of related scanning probe microscopes that are particularly relevant to soft materials. It also shows how techniques such as conductive AFM go beyond structural measurements to image the functional properties of materials relevant to applications such as solar cells. A wide range of spectroscopic techniques has also been reviewed, showing how they can be applied to learn about the interactions between conductive polymers and nanostructured... 

The effect of the Tg of the latex on the film-formation behaviour of a series of 2-ethylhexyl acrylate/methyl methacrylate emulsion copolymers was studied. Stage 1 of fihn formation was examined using a combination of DMA and conductivity measurements. Stages 2 and 3 were investigated using calorimehic compensation, DSC, dielectric spectroscopy and atomic force microscopy. Comparison of the results from the different methods employed led to a detailed model of the film-formation process in which the temp, used relative to the minimum film-formation temp, determined the effectiveness of the processes. The relative usefulness of the techniques used in their ability to characterise the various stages in the film-formation process was assessed for these copolymer systans. 23 refs. 

Blodgett (L-B) technique [31 - 33], resulting in mono-, bi- or multilayers allows characterisation of the resulting L-B films by other techniques, e.g., atomic force microscopy (AFM), X-ray scattering [34] and many others. The present review will be restricted to thin films at liquid surfaces. 

Other microscopic techniques, such as optical (aspect ratio), SEM (surface morphology) and EDAX (elemental analysis), Raman microscopy and atomic force microscopy can be used to further characterise the product. 

The use is demonstrated of microscopic analysis techniques for the investigation of adhesive failure. PVC sheet was bonded to glass using a M35R hybrid UV curable adhesive based on epoxy resin. Atomic force microscopy and X-ray induction photoelectron spectroscopy were used for the chemical characterisation of of failure surfaces. 11 refs. 

The introduction and development of Micro-Thermal Analysis are described and discussed by Duncan Price in Chapter 3. The atomic force microscope (AFM) forms the basis of both scanning thermal microscopy (SThM) and instruments for performing localised thermal analysis. The principles and operation of these techniques, which exploit the abilities of a thermal probe to act both as a very small heater and as a thermometer, in the surface characterisation of materials are described in detail. The... 

The application of AFM and other techniques has been discussed in general terms by several workers [350-353]. Other complementary techniques covered in these papers include FT-IR spectroscopy, Raman spectroscopy, NMR spectroscopy, surface analysis by spectroscopy, GC-MS, scanning tunnelling microscopy, electron crystallography, X-ray studies using synchrotron radiation, neutron scattering techniques, mixed crystal infrared spectroscopy, SIMS, and XPS. Applications of atomic force spectroscopy to the characterisation of the following polymers have been reported polythiophene [354], nitrile rubbers [355], perfluoro copolymers of cyclic polyisocyanurates of hexamethylene diisocyanate and isophorone diisocyanate [356], perfluorosulfonate [357], vinyl polymers... 

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