Reconstructive changes

The in-plane scattering has been measured at several temperatures up to 950K (Fig. 12). The structure factors continuously evolve indicating that the internal structure of the reconstruction changes during anneals. The final structure, which is expected to be close to the final transformation state, fortunately yields much larger intensities than the octopolar reconstruction and several reconstruction rods and CTRs could be measured in this case. The out-of-plane CTRs still resemble the octopolar reconstruction showing that the number of planes involved remains close to that of the octopolar reconstmction. 

The surface structure of single-crystal faces of noble metals such as KgQtkl) and AvL hkJ) were found to be unreconstructed under defined electrochemical conditions. For example, a unreconstructed Ag(lll) surface domain on a terrace in contact with perchloric acid solution is shown in Fig. 1. Surface reconstruction changing the interatomic distance and symmetry of surface atoms can be induced thermally or by potential, as observed by other authors [12]. This phenomenon can be lifted by potential or by adsorption processes. Surface defects such as monatomic steps and... 

While the seafloor depths of the lysocline and CCD can be readily identified from sedimentary criteria, this information is of limited use without realistic knowledge of the rates at which calcium carbonate is lost from the sediments to dissolution. In practice, it is much easier to determine carbonate accumulation in the deep sea than it is to estimate carbonate loss. Yet the latter information is clearly needed in order to close sediment budgets and to reconstruct changes in the carbonate system. 

We are here only considering the early stages of the adsorption when the reconstruction remains. At large coverage, generally the reconstruction changes or disappears. 

A concrete kind and scopes of relaxation and reconstruction changes depend on type of chemical bonds of surface atoms. First of all within the framework of a generalized approach it is necessary to take into account four bond types van-der-Waals one, ionic, covalent, and metallic ones, not depending on the predominant binding in bulk solid. It is possible that there would be covalent-bonded surface atoms in the crystal with presumably ionic bond type or, vice versa, an ionic bond can take place at the surface of covalent crystal. 

The use of tree rings as archives of atmospheric Pb contamination has been seriously questioned [145,146], although Aberg et al. [147] reported more success. Bark pockets which become trapped in a tree as two branches grow together, show much promise for reconstructing changes in the isotopic composition of Pb in atmospheric aerosols [148,149]. 

Kinnard C, Zdanowicz CM, Fisher DA, Isaksson E, de Vernal A, Thompson LG. Reconstructed changes in Arctic sea ice over the past 1,450 years. Nature 2011 479 (7374) 509-512. 

By reconstruction of a substrate surface we mean large atomic displacements that cause rebonding (bond breaking and/or new bond formation) within the substrate. Frequently, but not always, such a reconstruction changes the two-dimensional lattice of the surface, creating or modifying or removing a superlattice. Reconstructions are of course usually accompanied by additional small relaxations. 

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