Adsorption on silver

PDI dispersed in a KBr matrix (b) reflection absorption IR spectrum of PDI self-assembled on a vacuum-evaporated thick Ag film  

IR-transparent Cap2 crystal (d) diffuse reflectance IR Fourier transform spectrum of PDI self-assembled on 2-3.5pm-size Ag powder [45], 

---

Lutzenkirchen-Flecht D and Strehblow FI-FI 1998 Bromide adsorption on silver in alkaline solution A surface analytical study Ber. Bunsenges. Phys. Chem. 102 826-32... 

Bowmaker et al. (1998) have also used IR from a synchrotron source in the SNIFTIRS mode to smdy cyanate adsorption on silver. The spectra are shown in Fig. 27.38. The far-IR spectrum shows a broad band at about 360 cm at electrode... 

Water adsorption on silver surfaces exposed into a ventilated shed in an urban-rural site of Cuba was studied [13] using quartz resonators covered with a silver layer. It was determined that in these indoor conditions water adsorption significantly diminishes when air temperature increases over 25°C at relative humidity ranges of 80-90% and 90-100%. All these results confirm the idea that an upper limit of temperature should be established for the estimation of time of wetness. 

Chemisorption measurements have shown that ethylene does not adsorb on pure silver, but only on a silver surface which has been preoxidized [339]. Complete coverage with an oxygen monolayer, however, also seems to destroy the capacity to adsorb ethylene, as was demonstrated by Force and Bell [114,116] (favouring the idea of adsorption on silver). Consequently, partial oxygen coverage seems to be a necessary condition for catalytic activity. 

It has been necessary to understand the relationship between molecular fine structure of cyanine dyes and important properties such as colour, dye aggregation, adsorption on silver halide and electrochemical potentials in order to design and prepare sensitizers with optimum performance. For general discussion of these topics and the mechanism of spectral sensitization, the reader is referred to recent surveys on the subject (B-77MI11401, 77HC(30)441). 

Apart from kinetic measurements, the studies of oxygen adsorption on silver (63, 64), electron work function variations accompanying oxygen adsorption (65-67), heat effects of adsorption (65), reactivity of oxygen adsorbed on silver (67), and oxygen isotopic exchange on silver (56-55) were used for the elucidation of the mechanism of the reaction. The papers cited contain references to the works of other authors that were used for the formulation of the reaction mechanism on a level with our results. Here we shall mention, first of all, the work by Twigg (69), who has ascertained... 

The coverage has been limited to the applications of coordination compounds or of the coordination chemistry of relatively soluble ligands and metal species. Numerous chemical agents in photographic systems function by means of adsorption on silver halide grains and silver metal surfaces. Such chemical interactions lie outside the confines of coordination chemistry defined for this work and have not been discussed. 

Valette, G., Hamelin, A. and Parsons, R. (1978) Specific adsorption on silver single crystals in aqueous solutions. Z. Phys. Chem. Neue Fol. 113, 71-89. 

For permanent fixation of 1 adsorption on silver-loaded adsorbents, such as zeolites, silica, or alumina, will be the choice [PI, W2]. The process is simple, the bed temperature may be relatively high, the product is a dry solid, the chemisorbed iodine is highly insoluble, and the adsorbent is very efficient in removing both organic and inorganic iodine from gas streams. 

Kalish and Burstein (60) found that the amount of oxygen adsorbed by a platinum layer adjacent to the surface was about one hundred times that required for a monolayer. Temkin and Kul kova (61) have noted a similar phenomenon for oxygen adsorption on silver. The amount of... 

Hamoir (1945) was able to fractionate amino acids into four groups by adsorption on silver sulfide. In general those amino acids that form the least soluble silver salts were the most strongly adsorbed. The order in which the amino acids are adsorbed on the column, is rather different from the order on other columns, so that a different type of group separation may be obtained. 

As discussed in Sections 2.4 and 2.5.4, the spectral contrast can be increased using MIR-OTEs. This approach has been used, for example, in the ATR studies of adsorption of lipid bilayers to Au [481], p-nitrobenzoic acid on Ag and Au [482] and electrochemical reactions on Au [434], Cu [483], steel [484], Pt [485], and iron [486] electrodes. The ATR technique with a Si MIRE covered by Ag and Au films was applied to the study of thiocyanate adsorption on silver and gold [487]. Enhanced SNR has been reported for the MIR in situ spectra of proteins adsorbed onto a Cu-coated cylindrical internal reflection element [488]. Since the optical path of the beam through a MIR OTE strongly depends on the wavelength, optical schemes with a fixed incident beam are not applicable in this case [362],... 

When the first Raman spectroscopic study of an adsorbate on an electrode surface was undertaken [36], it was found that spectra could not be obtained from a smooth surface. It was therefore decided to increase the surface area, and hence the number of scatterers present, by roughening the electrode. The system studied was pyridine adsorption on silver, from a O.lmoldm KCl solution, and the roughening was achieved by repeatedly sweeping the electrode potential from 4-0.2V vs SCE, where AgCl is formed, to —0.3V where this film is reduced back to silver. Following this treatment, very intense spectra of adsorbed pyridine were obtained. It was soon recognised that the intensity of the spectra could not be accounted for simply by the surface area increase (enhancements by factors in excess of 10 have been reported), and that an enhancement mechanism, later to become known as surface enhanced Raman scattering (SERS) was in operation. 

The Ag I Ag20 electrode was not frequently used. Earlier works on the Ag Ag20 electrode were discussed by Hamer and Craig [178] and briefly summarized by Ives and Janz [177]. Evidently the potential of such electrodes, as found in earlier works, was not quite stable and its drift to more negative values was observed in time. Hamer and Craig [178] explained these changes as due to not proper preparation of the electrode. Namely the Pt with deposited porous silver was dipped in a slurry of silver oxide before use. Instability could result from the oxygen adsorption on silver and the formation of a film of nonstoichiometric oxides on the surface. 

J, G. E. M. Fraaije, W. Norde, J. Lyklema, Interfacial thermodynamics of protein adsorbtion and ion co-adsorption. 111. Electrochemistry of bovine serum albumin adsorption on silver iodide, Biophys. Chem., 1991,41, pp. 263-276. 

It has been reported that horse cytochrome c in the bulk of the solution exists in the six-coordinated low spin state (LS) and that adsorption on silver sol induces a partial transformation from the low spin state to the five-coordinated high spin state (HS)24 23 pi e present SERS results reveal that cytochrome c adsorbed on a silver electrode exists mainly in the high spin state at -0.5 V (ferrous-form), which is characterized by the Raman line at 1546 cm , as shown in Figure 3 (curve C). 

Gantner, E., D. Steineit, and J. Reinhardt. 1985. Raman measurements of tributyl-phosphate after adsorption on silver hydrosols. Awo/. Chem. 57 (8) 1658—1662. 

---