Terrace growths

AFM of the (010) surface of silicalite, from which relative rates of terrace growth in different directions of the surface have been determined. [Figure reproduced from reference 41 with permission. Copyright 2003 American... 

Figure 3.26 Two spiral growths (left and center) and one terrace growth (right) on a crystal of polyoxymethylene grown from0.05% xylene solntion near room temperatnre.The three strnctures have joined to form parallel layers as described in the text. Transmission electron micrograph of nnknown magnification (likely about 5000x) from Barnes and Price [40] with permission from Elsevier.

Mobility of this second kind is illustrated in Fig. XVIII-14, which shows NO molecules diffusing around on terraces with intervals of being trapped at steps. Surface diffusion can be seen in field emission microscopy (FEM) and can be measured by observing the growth rate of patches or fluctuations in emission from a small area [136,138] (see Section V111-2C), field ion microscopy [138], Auger and work function measurements, and laser-induced desorption... 

In this case, however, if the step separation i is small, the consecutive steps are coupled via the terrace diffusion held, and the width cannot increase as fast as but increases slowly, like the edge-diffusion-limited growth, as [68]... 

Au(in) a potential step from -f500 mV vs. Cu/Cu (a) to -f450 mV results in the growth of small Cu islands at the steps of the gold terraces (b) (picture from [66] - with permission of the Peep owner societes). 

Polymeric carbon refers to chains of carbon monomers (surface carbide) that are connected by covalent bonds. It has been shown recently47 that the barrier for C-C coupling on flat surfaces (1.22 eV) is half that for a step site (2.43 eV), and may indicate that the growth of these polymeric species is favored on terraces. Polymeric carbon may also refer to carbon chains that contain hydrogen. In the case of CO hydrogenation on ruthenium catalysts, polymeric carbon has been identified as a less reactive carbon that forms from polymerization of CHX and has an alkyl group structure.48... 

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