Spectroscopic studies of surface

The interesting results obtained for silyl modified sandstones and model substrates via spectroscopic studies of surface reactions and bonding properties offered a good basis for the investigation of low surface area samples like silicon wafers. This material is used as one of the typical transducers for biosensors. The working principle of a sensor is schematically shown in Fig. 11. 

A number of spectroscopic studies of surface species formed when CO2 is adsorbed by both metals and metal oxides have been reported. 

Daturi, M. and L.G. Appel, Infrared spectroscopic studies of surface properties of Mo/Sn02 catalyst J. Catal, 209 pp. 427 32, 2002. 

Baca, M., Pigamo, A., Dubois, J., et al (2005). Fourier Transform Infrared Spectroscopic Study of Surface Acidity by Pyridine Adsorption on the Ml Active Phase of the MoVTe(Sb)NbO Catalysts Used in Propane Oxidation, Catal. Commun.,6, pp. 215-220. 

Rupprechter G, Weilach Ch. (2008) Spectroscopic studies of surface-gas interactions and catalyst restructuring at ambient pressure Mind the gap J Phys Condens Matter 20 184019. 

The rate-determining step of ammonia synthesis and decomposition on Ni powder was studied using tracer isotopes (determination of the stoichiometric number) at 743 K. Dissociative adsorption and desorption were the slowest steps [225]. Dissociative adsorption was studied in few cases. The slight extent of chemisorption of N2 at 523 K to 573 K was speculated to be atomic species on Ni powder [226]. A spectroscopic study of surface nitride on polycrystalline Ni was carried out under a N2 pressure of 200 Torr [227]. 

Diamond is finding application as an electrode material because of its extremely wide potential window in aqueous solution, low background currents, resistance to fouling, chemical stability in aggressive environments, lack of surface oxide, transparency, and relative ease of functionalization. These attributes make diamond especially attractive for sensors, for the generation of highly reactive intermediates, for electrosynthesis, and for spectroscopic studies of surface processes. Furthermore, the inter-relationship between surface conductivity and the chemical environment provides another means for the study of diamond and may serve as the basis for sensors. 

Goodman D W 1996 Chemical and spectroscopic studies of metal oxide surfaces J. Vac. Sc/. Technol. A 14 1526... 

Recent space-probe and earth-based spectroscopic studies of the planet Venus suggest how much remains to be learned about the other planets. Earlier estimates of the surface temperature of Venus placed it near 60°C. The more detailed studies show, however, that two characteristic temperatures can be identified, —40°C and 430°C. The lower temperature is attributed to light emitted front high altitude cloud tops. The higher temperature is likely to be the average surface temperature. 

Secondary Ion Mass Spectroscopic Studies of Adsorption and Reaction at Metal Surfaces Correlations with Other Surface-Sensitive Techniques... 

Vibrational spectroscopic studies of heterogeneously catalyzed reactions refer to experiments with low area metals in ultra high vacuum (UHV) as well as experiments with high area, supported metal oxides over wide ranges of pressure, temperature and composition [1]. There is clearly a need for this experimental diversity. UHV studies lead to a better understanding of the fundamental structure and chemistry of the surface-adsorbate system. Supported metals and metal oxides are utilized in a variety of reactions. Their study leads to a better understanding of the chemistry, kinetics and mechanisms in the reaction. Unfortunately, the most widely used technique for determining adsorbate molecular structure in UHV,... 

Beden B, Juanto S, Leger JM, Lamy C. 1987b. Infrared spectroscopic study of the methanol adsorbates at a platinum electrode Part III Structural effects and behaviour of a polycrystalline surface. J Electroanal Chem 238 323-331. 

The experimental evidence, first based on spectroscopic studies of coadsorption and later by STM, indicated that there was a good case to be made for transient oxygen states being able to open up a non-activated route for the oxidation of ammonia at Cu(110) and Cu(lll) surfaces. The theory group at the Technische Universiteit Eindhoven considered5 the energies associated with various elementary steps in ammonia oxidation using density functional calculations with a Cu(8,3) cluster as a computational model of the Cu(lll) surface. At a Cu(lll) surface, the barrier for activation is + 344 k.I mol 1, which is insurmountable copper has a nearly full d-band, which makes it difficult for it to accept electrons or to carry out N-H activation. Four steps were considered as possible pathways for the initial activation (dissociation) of ammonia (Table 5.1). 

The Scanning Tunneling Microscope has demonstrated unique capabilities for the examination of electrode topography, the vibrational spectroscopic imaging of surface adsorbed species, and the high resolution electrochemical modification of conductive surfaces. Here we discuss recent progress in electrochemical STM. Included are a comparison of STM with other ex situ and in situ surface analytic techniques, a discussion of relevant STM design considerations, and a semi-quantitative examination of faradaic current contributions for STM at solution-covered surfaces. Applications of STM to the ex situ and in situ study of electrode surfaces are presented. 

An added difficulty that arises in the in-situ spectroscopic study of electrocatalytic systems in solution is that the active species will be located in the vicinity of the electrode so that the material in solution will generally represent a large background signal making the detection and identification of related species difficult. Thus, it would be ideal to be able to probe only that region proximal to the electrode surface and furthermore to be able to obtain structural information of the species involved. 

Gillies, K.J.S. and Urch, D.S. (1983). Spectroscopic studies of iron and carbon in black surfaced wares. Archaeometry 25 29-44. 

Bradley, J.S. et al., Surface spectroscopic study of the stabilization mechanism for shape-selectively synthesized nanostructured transition metal colloids, J. Am. Chem. Soc., 122, 4631, 2000. 

Recent work by Stipp and Hochella (1991) provide evidence for the processes of reconfiguration and hydration at the calcite surface. These results may provide a basis for future spectroscopic studies of trace metal adsorption and subsequent solid-solution formation. 

Spectroscopic techniques may provide the least ambiguous methods for verification of actual sorption mechanisms. Zeltner et al. (Chapter 8) have applied FTIR (Fourier Transform Infrared) spectroscopy and microcalorimetric titrations in a study of the adsorption of salicylic acid by goethite these techniques provide new information on the structure of organic acid complexes formed at the goethite-water interface. Ambe et al. (Chapter 19) present the results of an emission Mossbauer spectroscopic study of sorbed Co(II) and Sb(V). Although Mossbauer spectroscopy can only be used for a few chemical elements, the technique provides detailed information about the molecular bonding of sorbed species and may be used to differentiate between adsorption and surface precipitation. 

---