Ag surface

NakatsujI H and Nakal H 1990 Theoretical study on molecular and dissociative chemisorptions of an O2 molecule on an Ag surface dipped adcluster model combined with symmetry-adapted cluster-configuration interaction method Chem. Phys. Lett. 174 283-6... 

NakatsujI H, Nakal H and Fukunishi Y 1991 Dipped adcluster model for chemisorptions and catalytic reactions on a metal surface Image force correction and applications to Pd-02 adclusters J. Chem. Phys. 95 640-7 NakatsujI H and Nakal H 1992 Dipped adcluster model study for the end-on chemisorption of O2 on an Ag surface Can. J. Chem. 70 404-8... 

Zhen-Ming Hu and NakatsujI H 1999 Adsorption and disproportionation reaction of OH on Ag surfaces dipped adcluster model study Surf. Sci. 425 296-312... 

Capacitance data for various crystal faces are available for Bi and Sb.28 As a broad trend, the faces with more negative values of Eam0 show higher values of C. Although this is qualitatively in line with the behavior of real Ag surfaces, the response of Bi and Sb is complicated by their semimetal nature, which gives rise to space-charge effects. For this reason it is not straightforward to compare the absolute values of C and their crystal face sequences with those of metals. 

Equations (5.18) and (5.19), particularly the latter, have only recently been reported and are quite important for solid state electrochemistry. Some of then-consequences are not so obvious. For example consider a solid electrolyte cell Pt/YSZ/Ag with both electrodes exposed to the same P02, so that Uwr = 0. Equation (5.19) implies that, although the work functions of a clean Pt and a clean Ag surface are quite different (roughly 5.3 eV vs 4.7 eV respectively) ion backspillover from the solid electrolyte onto the gas exposed electrode surfaces will take place in such a way as to equalize the work functions on the two surfaces. This was already shown in Figs. 5.14 and 5.15. 

The creation of two types of chemisorbed oxygen on Pt and Ag surfaces subject to NEMCA conditions is clearly shown by cyclic voltammetry (Fig. 5.27)319,50,52 or by the similar Potential-Programmed-Reduction (PPR)... 

Significant observations regarding the origin of NEMCA have been also made using Ultra-violet Photoelectron Spectroscopy (UPS) with Pt and Ag electrodes deposited on YSZ. In this case the work function of the electrode can be determined from the cutoff energy of secondary electrons (Fig. 5.43).24,68 As shown in Fig. 5.8b the change in the work function of the gas-exposed Ag surface is very close to the imposed electrode potential change AUwr. 

H. R. Dettwiler, A. Baiker, and W. Richarz, Helvetica Chim. Acta 62 (1979) 1689. (Specific rates taken from this paper were obtained by assuming the Ag surface area equal to the BET surface area of the catalyst. Justification for this is presented in Ref. (24). 

A noteworthy feature of the photoacoustic spectra shown in Figure 2 Is the presence of water librations. These are frustrated rotations and have been observed for ice (24) by infrared spectroscopy, as well as for water adsorbed on Ft and Ag surfaces by electron energy loss spectroscopy (25-27). The three libration modes have been associated with the bands at 600, 538 and 468 cm" > this set of peaks occurs for water adsorbed on both the hydroxylated and methoxylated silica. 

The above conclusion was confirmed by control experiment. It is well known [47] that freshly deposited silver films are very efficient in adsorption of atomic oxygen at room temperature. Therefore, the attachment covered by Ag-film similar to that with a Co304-covering should completely stop the flux of oxygen atoms. (The experiment with the known source of oxygen atoms - hot Pt-filament - confirms the efficiency of above attachment). It occurred [44] that in case of particles leaving the Ag surface such an attachment completely shuts down the flux of particles from the surface of the sample under investigation. 

Fig. 5.49 A microphotograph of low pyramid formation during electrocrystallization of Ag on a single crystal Ag surface. (By courtesy of E. Budevski)...

A similar picture is revealed for the octadienediyl-Ni11 complex involved in the C12-cyclotrimer reaction channel.110 In the ri p1 species, 2b, 3b, r 2-butadiene preferably occupies the fourth position around Ni11, while the coordination of butadiene is unfavorable at the AG surface for the bis(r 3) species 4b. The predominant configurations are 2b and 4b, while bis(r(1) species represent isomers lying at much higher energies. The bis(r 3) species 4b is favorable by 5.6 kcal mol-1 (AG) relative to 2b, which is due to the limited ability of the weak donor butadiene to electronically stabilize the p ri C1) coordination mode. 

Figure 3.15 O Is / Ag 3d5/2 XPS intensity ratio as a function of take-off angle for two oxygen species on polycrystalline silver. The data corresponding to an O 1 s binding energy of 528.4 eV are attributed to subsurface oxygen in Ag, the other with a binding energy of 530.5 eV to oxygen atoms adsorbed on the Ag surface (data from Baschenko et al. (39J).

Sonnenfeld, R. SPIE 88 Conference Proceedings, in press) have both reported in situ STM images of electrode surfaces on which metals have been electrochemically deposited. Morita et. al. (61) have examined Ag surfaces in situ in the presence of chloride ion. 

It is likely that the decreases observed can be rationalized in terms of two contributions. Changes in surface optical properties resulting from modification by the foreign metal have been shown to decrease the electromagnetic enhancement contribution to SERS. However, for the case of Pb UPD on Ag, this effect has been shown to account for only ca. 40% of the decrease in going from zero coverage to one monolayer.(14) Moreover, this model does not account for the relatively rapid decrease in intensity observed with the deposition of small (i.e., less than 20% of a monolayer) amounts of Pb on the Ag surface. 

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