Adding Atoms

Once a molecule (Fig. 11) has been added at the sample Node, the user can add atoms and subsequently bonds (see 2.14) through the Molecule menu or by a right mouse click on the Molecule Node. In this context, the term bond is loosely defined to include not only bonds but also interactions between electron spins and either nuelear spins (superhyperfine interaction) or other electron spins (exchange interaetion). Adding an atom displays a Periodic Table (Fig. 12) from which the user ean select an atom by clicking (left mouse button) on the appropriate element. The atom is then added to the Molecule in the Explorer. 

---

The search in the Theilhcimer reaetion database [62] provides 161 reactions for this query. If the search is performed without any additional bond spheres (covering only atoms of the inner sphere with a dark gray bac kgroiind in Figure 10.3-42 as well as the added atom groups on the precursor side), 705 reactions arc obtained in the Theilhcimer database. The result of this search is less precise than that of the first search. Additionally, reactions forming any kind of C-0 bonds (c.g., making an ether bond instead of an ester bond) arc found. However, in both searches too many hits arc obtained in order to detect suitable reactions in a reasonable... 

Formed by adding atoms beyond each of the vertical faces of a right triangular prism. 0.732... 

This pattern is similar to that for the formation process of ad-atoms in metal plating [90],... 

The energy band describing the bonding in lithium metal can be constructed by adding atoms one at a time. 

Motoo, S., Electrocatalysis by ad-atoms, Proc. Electrochemical Society, PV 84-12, 1994, p. 331. 

Motoo S, Watanabe M. 1980. Electrocatalysis by ad-atoms Part VII. Enhancement of CO oxidation on platinum by As ad-atoms. J Electroanal Chem 111 261-268. 

Uchida H, Ikeda N, Watanahe M. 1997. Electrochemical quartz crystal microhalance study of copper ad-atoms on gold electrodes. Part II. Further discussion on the specific adsorption of anions from the solutions. J Electroanal Chem 424 5-12. 

Watanabe M, Motoo S. 1975a. Electrocatalysis by ad-atoms. Part in. Enhancement of the oxidation of carbon monoxide on platinum by mthenium ad-atoms. J Electroanal Chem 60 275-283. 

Watanabe M, Shibata M, Motoo S. 1985. Electrocatalysis hy ad-atoms. PartXn. Enhancement of carbon monoxide oxidation on platinum electrodes by oxygen adsorbing ad-atoms (Ge, Sn, Pb, As, Sb and Bi). J Electroanal Chem 187 161-174. 

Smirnova NW, Petrii OA, Grzejdziak A. 1988. Effect of ad-atoms on the electro-oxidation of ethylene glycol and oxalic acid on platinized platinum. J Electroanal Chem 251 73-87. 

Adzic RR, Markovic NM. 1982. Structural effects in electrocatalysis Oxygen and hydrogen peroxide reduction on single crystal gold electrodes and the effects of lead ad-atoms. J Electroanal Chem 138 443-447. 

Fig. 5.24 Crystalline metal face (a) ad-atom, (b) ad-atom cluster, (c) a kink (half-crystal position), (d) atom at the step, (e) atom in the kink, (f) vacancy, (g) vacancy cluster. (According to E. Budevski)... 

It was mentioned on page 306 (see Fig. 5.24) that, even at room temperature, a crystal plane contains steps and kinks (half-crystal positions). Kinks occur quite often—about one in ten atoms on a step is in the half-crystal position. Ad-atoms are also present in a certain concentration on the surface of the crystal as they are uncharged species, their equilibrium concentration is independent of the electrode potential. The half-crystal position is of basic importance for the kinetics of metal deposition on an identical metal substrate. Two mechanisms can be present in the incorporation of atoms in steps, and thus for step propagation ... 

In the first case, the rate of deposition depends on the equilibrium concentration of ad-atoms, on their diffusion coefficient, on the exchange current density and on the overpotential. In the second case, the rate of deposition is a function, besides of the geometric factors of the surface, of the exchange current and the overpotential. This mechanism is valid, for example, in the deposition of silver from a AgN03 solution. 

Note that all the added atoms in steps 4 and 5 have the same oxidation number as the atoms already in the equation. The atoms changing oxidation number have already been balanced in steps 1 and 2. 

The charges balance, in accordance with rule 3 above. Finally, it may be regarded as reasonable to assume that the added oxygen ends up as O2-. In this case each added atom of oxygen must gain two electrons. These will be taken from another source in the crystal, thereby generating two positive holes, h ... 

The unsaturated open-chain hydrocarbons include the alkene or olefin series, the diene series, and the alkyne series. The alkene series is made up of chain hydrocarbons in which a double bond exists between two carbon atoms. The general formula for the series is CnH2n, where n is the number of carbon atoms. As in the paraffin series, the lower members are gases, intermediate compounds are liquids, and the higher members of the series are solids. The alkene series compounds are more active chemically than the saturated compounds. They react easily with substances such as halogens by adding atoms at the double bonds. 

The cyanide ion was one of the first adsorbed ions which was found to be surface enhanced (8,9) on silver electrodes. In this first stage of SERS investigation of the cyanide ion, it was assumed to be linearly bonded to Ag, through the carbon atom, perpendicular to the metal surface (9). However faced with the pressure of explaining the SERS mechanism, alternative structures were proposed. With the conception of the ad-atom model for SERS, Otto conjectured that the main SERS band was due... 

The NiAs structure is an important reference type because of its several (filled-up and defect) derivative structures. If atoms are left out of the metal layers in an ordered way, defects superstructures are obtained the Cdl2 type is obtained when all the metal atoms are omitted in alternate layers. On the contrary other derivative structures (filled-up structures) may be obtained by adding atoms in the same layers as... 

---