Fractal atomic force microscopy

We have considered briefly the important macroscopic description of a solid adsorbent, namely, its speciflc surface area, its possible fractal nature, and if porous, its pore size distribution. In addition, it is important to know as much as possible about the microscopic structure of the surface, and contemporary surface spectroscopic and diffraction techniques, discussed in Chapter VIII, provide a good deal of such information (see also Refs. 55 and 56 for short general reviews, and the monograph by Somoijai [57]). Scanning tunneling microscopy (STM) and atomic force microscopy (AFT) are now widely used to obtain the structure of surfaces and of adsorbed layers on a molecular scale (see Chapter VIII, Section XVIII-2B, and Ref. 58). On a less informative and more statistical basis are site energy distributions (Section XVII-14) there is also the somewhat laige-scale type of structure due to surface imperfections and dislocations (Section VII-4D and Fig. XVIII-14). 

Figure 10. Three-dimensional AFM images of (a) Pt/polished AI2O3, (b) Pt/etched Ni, and (c) Pt/unpolished AI2O3 electrodes. Reprinted from J. -Y. Go et al., A study on ionic diffusion towards self-affine fractal electrode by cyclic voltammetry and atomic force microscopy, J. Electroanal. Chem., 549, p. 49, Copyright 2003, with permission from Elsevier Science.

Li and Park developed a technique to obtain surface fractal dimension using atomic force microscopy (AFM). The fractal dimension is obtained from a plot of log f fyv/x,y,s)dxdy vs. log(e) according to a variation method described below ... 

Li, T. Park, K. Fractal analysis of pharmaceutical particles by atomic force microscopy. Pharm. Res. 1998, 15 (8), 1222-1232. 

Stromme, M.. Niklasson, G.A., and Granqvist, C.Q. 1996b. Fractal surface dimension from cyclic I-V studies and atomic-force microscopy Role of noncontiguous reaction sites. Physical Review B 54, 17884-17887. 

Atomic force microscopy (AFM) has an important application in fractal analysis because it provides data characterizing the material surface in the scale from a few angstroms to hundreds of micrometers with great precision. In the AFM method each sample is scanned in a few different places so as to obtain a representative view of the whole surface topography. For powders a few particles are chosen and a surface fi agment is scanned on each of them. 

Happo N, Fujiwara M, Iwamatsu M, Horii K (1998) Atomic force microscopy study of self-affine fractal roughness of porous silicon surfaces. Jpn J Appl Phys 37 3951-3953 Harsanyi J, Habermeier HU (1987) Fractal micropattems generated by anodic etching. Microelectron Eng 6(1—4) 575-580... 

Fractal dimensions can be estimated from peak height and spacing such as provided by atomic force microscopy micrographs, yielding much information... 

Synthesis of a new modification of silica soluble in THF is described. At the first synthetic step, a hyperbranched polyethoxysiloxane (HBPES) is synthesized by heterofunctional condensation using triethoxysilanol previously generated in reaction mixture by neutralization of correspondent sodium salt with acetic acid. At this step, the process was monitored by IR spectroscopy, SEC, and Si NMR spectroscopy. At the second step, hydrolysis and intramolecular condensation involving silanol groups is carried out to yield silica sol macromolecules. A SAXS method was used to determine the size and fractal coefficient of trimethylsilated derivatives and silica sols obtained. An atomic-force microscopy imaging of silica sol supported on a mica substrate showed the silica sol particles to be predominantly spherical in shape. Prospects for theoretical, experimental and practical applications of silica sols are discussed. 

The experimental analysis of particulate-filled nanocomposites butadiene—styrene mbber/fullerene-containing mineral (nanoshungite) was fulfilled with the aid of force-atomic microscopy, nanoindentation methods, and computer treatment. The theoretical analysis was carried out within the frameworks of fractal analysis. It has been shown that interfacial regions in the aforementioned nanocomposites are the same reinforcing element as nanoliller. The conditions of the transition from nano to microsystems were discussed. The fractal analysis of nanoshungite particles aggregation in polymer matrix was performed. It has been shown that reinforcement of the studied nanocomposites is a true nanoeffect. 

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