Rough surface idealized

Scaling is not always related to temperature. Calcium carbonate and calcium sulfate scaling occur on unheated surfaces when their solubiUties are exceeded in the bulk water. Metallic surfaces are ideal sites for crystal nucleation because of their rough surfaces and the low velocities adjacent to the surface. Corrosion cells on the metal surface produce areas of high pH, which promote the precipitation of many cooling water salts. Once formed, scale deposits initiate additional nucleation, and crystal growth proceeds at an accelerated rate. 

A planar polished surface reflects heat radiation in a similar manner with which it reflects light. Rough surfaces reflect energy in a diffuse manner hence radiation is reflected in all directions. A blackbody absorbs all incoming radiation and therefore has no reflection. A perfect blackbody does not exist a near perfect blackbody surface such as soot reflects 5% of the radiation, making it the standard for an ideal radiator. 

The fractal dimension D of an ideal solid is 3.00, of a perfectly flat surface 2.00, and of a straight line 1.00—the familiar geometric dimensions. Porous solids and rough surfaces, however, have effective dimensions corresponding to fractional values of D. 

Figure A3.10.8 schematically depicts a Si(lOO) surface (a) being etched to yield a rough surface (b) and a more regular surface (c). The surfaces shown here are seen to consist of steps, terraces and kinks, and clearly have a three-dimensional character, rather than the two-dimensional character of an ideally flat, smooth surface. The general etching mechanism is based on the use of halogen molecules, the principal etchants used in dry etching. Upon adsorption on silicon at room temperature, Br2 dissociates to form bromine atoms, which react with surface silicon atoms. Then, if an external source of energy is provided, for example by heating Si...

If the structure factor for an ideally smooth surface, Fldeai, is written by summing laterally over a single surface unit cell and vertically over all z (including the semiinfinite sum over the bulk crystal, the sum over the surface layer and any fluid layer above the surface) as written in Equation (16), the structure factor for a rough surface can be written ... 

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