Growth of islands with stepped surfaces

Because values of step formation energy /3i depend on changes in lengths of chemical bonds, it is likely that the values will be sensitive to imposed background strain in the crystal. This point was pursued in Section 8.8.3 where it was demonstrated that there is a potential for the step formation energy to become negative for strain of one sign or the other. 

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Figure 6.2-12 Cyclic voltammogram of 0.1 - 1 mmol dm Geb on gold in dry [BMIMj PFg , starting at-500 mV towards cathodic (a) and anodic (b) regime. Two quasireversible (E, and E2) and two apparently irreversible (E4 and E5) diffusion-controlled processes are observed. E3 is correlated with the growth of two-dimensional islands on the surface, E4 and E5 with the electrodeposition of germanium, Ej with gold step oxidation, and E, probably with the iodine/iodide couple. Surface area 0.5 cm (picture from [59] - with permission of the Peep owner societes).

A simple topochemical model for the growth of NiO islands on the Ni surface during the reaction of oxygen with a Ni(lll) crystal is clearly described by Holloway and Hudson [112]. They considered three cases in which the rate-determining step is, respectively (a) oxygen sorption from the gas phase (surface diffusion is fast), (b) surface diffusion of oxygen, and (c) oxygen insertion over the island boundary. 

Deposition of Au onto this surface leads to the nucleation of Au islands at the intersection of clean Cu stripes thus leading to a square island lattice with a period of 50 A [83,86-88]. The N-covered Cu(100) surface has also been used for the growth of so far less well-ordered lattices of Fe and Cu [89], Co [90-92], Ag [93,94], and Ni [95], We note that square lattices can in principle also be created on Au(f4,f5,f5) since this miscut leads to 70 A step distance, which is equal to the reconstruction period. However, the steps are already far apart reaching the limit of the elastic step repulsions which may render global order difficult. Finally we note that another interesting alternative square template, although with smaller lattice constant, is presented by the (3 /3 x 5)-phase of V-oxide on Rh(lll) [96]. 

Monatomic steps at real surfaces do significantly influence not only the nucleation act, but also the spreading and overlapping of 2D islands, which determine the shape of potentiostatic current transients. Neglecting the adsorptive contribution in eq. (3.64), i.e., ep Qcd, and assuming a barrierless nucleation and growth of a condensed 2D Mcads phase only at steps with a regular pattern characterized by a... 

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