Nucleation substrate defect-related

These traps close to the substrate are related to structural defects, which are generated when the 6T crystallites nucleate on the glass surface. 

In this respect, the cluster size, from which on the defect-induced perturbation on the electronic structure disappears, is a key quantity. The calculations showed [178] that effect of the surface defects on the adhesion energy decreases rapidly with cluster size. Thus, for particles of nanometer size, differences in the bonding to the substrate tend to vanish as the larger polarizability of the particle screens the effect of the defect and the relative effect of defect-related bonds become less important due to the larger number of metal-oxide bonds at the interface. However, because point defects are the most likely sites for the initial steps of nucleation, one has to expect that also large metal particles are still located at these sites unless the temperature is sufficiently high to permit diffusion of particles. 

I believe, it is fair to state that scanning tunneling microscopy and related techniques such as atomic force microscopy have a tremendeous potential in metal deposition studies. The inherent nature of the deposition process which is strongly influenced by the defect structure of the substrate, providing nucleation centers, requires imaging in real space for a detailed picture of the initial stages. This is possible with an STM, the atomic resolution being an extra bonus which helps to understand these processes on... 

The latter point brings us to an important question in the field of catalysis by supported metal particles to which extent is the chemical reactivity of a (sub-) nanocluster affected by the interaction with the substrate Very few theoretical studies were dedicated to this problem, and most of them are related to the surface of MgO, an oxide which interacts weakly widi the supported particle, as shown above. Still, the knowledge accumulated in the course of the years on the structure of surface defects and morphology of the MgO surface allows one to analyze some of the mechanisms which can modify the chemical properties of a supported cluster as a function of the site where nucleation has occurred. 

Determination of structure and crystalline defects is necessary to understand the physical properties of particles nucleated on crystalline substrates, in a matrix, or directly in the gas phase or in solution. Indeed, the reactivity of small particles and their magnetic and optical properties are related to their size, structure, morphology, and lattice deformations. 

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