Thermal roughening

Solid metal electrodes with a crystalline structure are different. The crystal faces forming the surface of these electrodes are not ideal planes but always contain steps (Fig. 5.24). Although equilibrium thermal roughening corresponds to temperatures relatively close to the melting point, steps are a common phenomenon, even at room temperature. A kink half-crystal position—Fig. 5.24c) is formed at the point where one step ends and the... 

More recently, the question of thermal roughening has also been addressed in the study of metal surfaces. Detailed He difiraction studies from the high Miller index (113) surface of Cu and Ni proved the existence of a roughening transition on these surface. These studies were performed by means of He scattering. Let us make first two short comments. 

The thermal roughening of naturally chiral metal surfaces must have some impact on their enantiospecific interactions with chiral adsorbates. Sholl et al. have also studied the effects of step roughening on the adsorption of small chiral molecules [11, 17]. Molecular simulation of small chiral alkanes adsorbed on ideal and roughened Pt(643) surfaces revealed that enantioselectivity is preserved during... 

Power TD, Asthagiri A, ShoU DS (2002) Atomically detailed models of the effect of thermal roughening on the enantiospedficity of naturally chiral platinum surfaces. Langmuir 18 3737... 

In this paper, we advance a thermodynamic interpretation of the effect of chloride on copper surfaces in plating solutions. We have pursued this interpretation experimentally by observation of faceting on the sub-micron scale on low-index surfaces of copper single crystals. In the two sections that follow, relevant portions of the theory of equilibrium roughness and its relation to macroscopic faceting are presented. We consider how adsorbed chloride may stabilize the Cu(100) surface at equilibrium and relate this mechanism to simple models of thermal roughening. AFM experiments on copper plating on low-index copper crystal electrodes are then described and related to the theory. 

K). The changes in slope indicate changes in the mechanism of surface diffusion. While, at low temperatures, adatom diffusion or adatom-surface atom exchange appears to be the dominant atom-transport mechanism, the diffusion of surface vacancies created by thermal roughening is likely to be dominant at high temperatures to account for the increased activation energies. For example, copper adatom and vacancy diffusion rates in the Cu(l 10) crystal face are given by... 

From the viewpoint of the deposition or growth process, it would be of interest to have a quantitative description of the surface structure. At room temperatures, thermal roughening is not expected to produce monatomic steps but, if present, they may show a rather high concentration of kinks. The mean distance So/a between kinks in atomic diameters is given for the most dense step on a (100) face of a fee crystaP by... 

With a typical value of A(7j = 150 kJ moF or = 4.1 x 10 ° J per bond, thermal roughening causes every 75th atom of the step to be in a kink position. 

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