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The population of Ag-occupied half-unit cells ͑HUC's͒ on Si(111)7ϫ7 surface resulting from growth and annealing experiments is observed by scanning tunneling microscopy. The temperature dependence of Agobject density and preference in HUC occupation are measured. The results are interpreted with the help of a coarse-grained kinetic Monte Carlo model. The key kinetic mechanisms affecting Ag motion are determined, in particular transient mobility of deposited Ag atoms and the existence of a highly stable configuration of six Ag atoms in a HUC. The attempt frequency and barrier to hopping of a single Ag atom between HUC's are estimated.

Chemical identification of individual atoms in mixed In-Sn chains grown on a Si(100)-(2 × 1) surface was investigated by means of room temperature dynamic noncontact AFM measurements and DFT calculations. We demonstrate that the chemical nature of each atom in the chain can be identified by means of measurements of the short-range forces acting between an AFM tip and the atom. On the basis of this method, we revealed incorporation of silicon atoms from the substrate into the metal chains. Analysis of the measured and calculated short-range forces indicates that even different chemical states of a single atom can be distinguished.

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