Restructuring of surface

There has been a general updating of the material in all the chapters the treatment of films at the liquid-air and liquid-solid interfaces has been expanded, particularly in the area of contemporary techniques and that of macromolecular films. The scanning microscopies (tunneling and atomic force) now contribute more prominently. The topic of heterogeneous catalysis has been expanded to include the well-studied case of oxidation of carbon monoxide on metals, and there is now more emphasis on the flexible surface, that is, the restructuring of surfaces when adsorption occurs. New calculational methods are discussed. 

Figure 7.8 Restructuring of surface atoms at step sites of a clean surface.

Tabulations of some surface structures may be found in a review by Van Hove and coworkers (Van Hove et al., 1989) and the reviews by Watson that compare the results of surface structure determinations utilizing different crystallographic techniques (Watson, 1990, 1992). Van Hove has also published a recent review of crystal surface structure, without the tabular presentation of the structural data (Van Hove, 1992). Van Hove and Somorjai have reviewed surface structure from the point-of-view of adsorbate induced restructuring of surfaces (Van Hove and Somorjai, 1989). Ohtani and coworkers have listed all observed overlayer structures and surface symmetries, albeit without any reference to the detailed surface structure (Ohtani et al., 1987). 

Diffusion experiments at surfaces are designed to measure self-diffusion or the diffusion of adsorbates. The techniques used [49-55) may provide atomic-scale diffusion data or macroscopic diffusion parameters. The techniques that provide atomic-level information include (a) field ion microscopy, which can be used to observe the surface migration of isolated adatoms or clusters of atoms, (b) field electron microscopy, and (c) scanning tunneling microscopy (for descriptions of the techniques, see references [56-68]. Macroscopic mass transport along the surface can be monitored by the use of radiotracers or by techniques that monitor the restructuring of surfaces as a function of time. 

Surface-atom displacements play an important role in inducing the restructuring of surfaces. 

Adsorbate-induced restructuring of surfaces could explain the formation of cluster-like bonding of adsorbates on metal surfaces. Discuss how the strength of the chemisorption bond is likely to influence the restructuring of metal surfaces. 

Adsorbate Induced Restructuring. Perhaps, the most striking observation of recent years is the adsorbate induced restructuring of surfaces. This can be demonstrated by the restructuring of the nickel (100) face(13) in the presence of half a monolayer of carbon... 

Segregation of the planes of cobalt metal crystallites means increase of the number of surface atoms without change of particle diameter, the driving force being an increase of the number of sites for CO-adsorption. This restructuring of surface planes also concerns disproportionation of the sites... 

In conclusion, it is evident that the interface can easily be restructured by polymer molecules adhering to it in a rich variety of ways. This restructuring of surfaces is a general phenomenon which must be discussed next. 

K. Kern, H. Niehus, A. Schatz, P. Zeppenfeld, J. George, G. Comsa, Long-range spatial selforganization in the adsorbate-induced restructuring of surfaces—Cu(110)-(2 x 1)0. Phys. Rev. Lett. 67(7), 855-858 (1991)... 

---