Atomic mismatch

Figure 15 Analogies for the cyclical subproblem of methylcyclohexylketone (Fig. 14) in decreasing order of similarity exact match, real atom mismatch, a-origin atom mismatch, and origin atom mismatch.

A grain boundary is the boundary region separating two grains where there is some atomic mismatch. 

Within the vicinity of a grain boundary (which is several atomic distances wide), there is some atomic mismatch between two adjacent grains that have different crystallographic orientations. 

Zinc sulfide, ZnS, has been epitaxially deposited by the dual bath approach on Au(lll) surface and studied by STM and XPS [48]. The first complete ECALE cycle resulted in the formation of nanocrystallites of ZnS randomly distributed across Au(l 11) terraces, on account of lattice mismatch induced strain between ZnS and Au(lll) - although the mismatch is only 0.13% for ZnS/Au(lll). Atomically resolved STM images showed the ZnS/Au(lll) monolayer to be sixfold symmetric. The average diameter of the crystallites was 10 5 nm and the apparent coverage 0.38. 

Dislocations Dislocations are stoichiometric line defects. A dislocation marks the boundary between the slipped and unslipped parts of crystal. The simplest type of dislocation is an edge dislocation, involving an extra layer of atoms in a crystal (Fig. 25.2). The atoms in the layers above and below the half-plane distort beyond its edge and are no longer planar. The direction of the edge of the half-plane into the crystal is know as the line of dislocation. Another form of dislocation, known as a screw dislocation, occurs when an extra step is formed at the surface of a crystal, causing a mismatch that extends spirally through the crystal. 

Van der Woude and Miedema [335] have proposed a model for the interpretation of the isomer shift of Ru, lr, Pt, and Au in transition metal alloys. The proposed isomer shift is that derived from a change in boundary conditions for the atomic (Wigner-Seitz) cell and is correlated with the cell boundary electron density and with the electronegativity of the alloying partner element. It was also suggested that the electron density mismatch at the cell boundaries shared by dissimilar atoms is primarily compensated by s —> electron conversion, in agreement with results of self-consistent band structure calculations. 

Stoichiometric reaction with matched S-carbamate having the D atom in the Z-position 733) in the presence of S,S-ligand 64 without a nucleophile solely formed (no other isomer was observed by NMR) the Mo-complex 74 without transposition of the label. The structure of 74 was probed based on NMR studies by comparison with NMR studies and the X-ray structure of the protio complex 71. Nucleophilic attack of sodium malonate on the Mo complex 74 provided the S-product 75, where the D atom remained at the Z-position. On the other hand, stoichiometric reaction with mismatched R-carbamate having the D atom in the Z-position 76 without a nucleophile generated the Mo complex 80 as sole product, based on NMR studies. The structure of the complex 80 was elucidated by NMR. In 80, Mo is located on the same face as in 74 but the D atom is transposed from the Z to the E position. The transposition could be explained as follows. Initially the n-allyl Mo-complex 77 (unobserved) must form with retention. Mo complex 77 is equilibrated into the more stable Mo complex 80, where the D atom is moved... 

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