Spectroscopy of adsorbed species

studies of the adsorption of CO Gerasimov et al.25 and Davydov et al44 observe adsorption both on V4+ and on V3+ ions in reduced catalysts, but hardly any adsorption in the oxidized state. Davydov et al45 concluded that propene is adsorbed on oxidized V205/A1203, mainly on Br nsted acid sites forming an alcoholate type complex. On reduced catalysts propene is adsorbed as a 7r-complex of V3+ and V4+ ions. 

In several investigations, it was shown that NH3 is adsorbed as the ammonium 

Pomonis and J. C. Vickerman, Proc. 7th International Congress on Catalysis, Tokyo, 1980, Kodansha Ltd., Tokyo, 1981, Part. B, p. 1368. 

Bazarova et al.so conclude from an i.r. study of V205/K2 S207 catalysts that a very complex system of at least four different vanadium compounds is formed and that the reaction conditions profoundly influence their relative amounts. Likhtenshtein et al.,sl using a high-temperature i.r. cell showed, for a similar system, that the vanadyl complexes are maintained above their melting point (370°C). 

Hanke et al.52 observed the disappearance of the OH-band at 3750cm-1 on Si02 by reaction with VOCl3. After hydrolysis this band reappears with a lower intensity showing that some of the Si-O-V bonds are also broken. A new band at 3665 cm-1 is ascribed to V-OH groups. 

---

A. A. Davydov, Infrared spectroscopy of adsorbed species on the surfaces of transition metal oxides, Wiley, Chichester, 1990. 

A.V. Kiselev and V.I. Lygin, in Infrared Spectroscopy of Adsorbed Species, L.H. Little (Ed.), Academic Press, New York, 1966. 

A.A. Davydov and C.H. Rochester, Infrared Spectroscopy of Adsorbed Species on the Surface of Transition Metal Oxides, Wiley, New York, 1990. 

Vibrational Spectroscopy of Adsorbed Species Bell, A. T. Hair, M. L., Eds. ACS Symposium Series No. 137 American Chemical Society Washington, DC, 1980. 

Raman spectroscopy of adsorbed species on surfaces (see Raman spectroscopy)... 

Little, L. H. "Infrared Spectroscopy of Adsorbed Species" Academic Press New York 1966. 

R.D. Kelley, J.J. Rush T.E. Madey (1979). Chem. Phys. Lett., 66, 159-164. Vibrational spectroscopy of adsorbed species on nickel by neutron inelastic scattering. 

The combined use of gas-volumetric adsorption measurements and of IR spectroscopy of adsorbed species indicated that, on pure-alumina-supported R catalysts, a large number and variety of Pt" sites exist. These are characterized by the frequent presence of multiple-vacancies, so that the coadsorption of various probes becomes possible, and the preadsorption of some probes does not reduce much the adsorbing capacity towards other probes. 

Morterra, C., Magnacca, G. (1996). A Case Study Surface Chemistry and Siuface Strudure of Catalytic Aluminas, as Studied by Vibrational Spectroscopy of Adsorbed Species. Catalysis Today, Vol.27, Nos.3, (February 19%), pp. 497-532, ISSN 0920-5861... 

More recently, the work of Lipkowski and coworkers has sought to quantify the application of the SSR in the study of adsorbed species. Lipkowski and coworkers have built up a quantitative treatment of the infrared spectroscopy of adsorbed species based upon the SSR in an elegant series of papers [16, 83, 85, 165, 170, 171] using the combination of SNIFTIRS and conventional electrochemical techniques such as differential capacitance measurements. Thus, Li, Roscoe, and Lipkowski [165] published a study in 1999 on the adsorption of the benzoate anion at... 

Morterra, C. and Magnacca, G. A case study surface chemistry and surface strue-ture of catalytic aluminas, as studied by vibrational spectroscopy of adsorbed species. Catal. Today 1996, 27, 497-532. 

This section has provided a simple outline of IR spectroscopy of adsorbed species at metal surfaces, aimed at an early researcher requiring a broad introduction to the technique. The past two decades have witnessed a major advance in the use of the RAIRS technique, with the use of FT spectrometers enabling relatively easy and versatile setups to be adopted in many laboratories. For simple adsorbates, the increase in the sensitivity of this technique combined with increased spectral and time resolution has enabled sophisticated experimental data to be recorded which, in turn, has led to advances in theories on structural, kinetic, and dynamical processes [4, 5]. For complex adsorbates, RAIRS stands out as probably the most useful starting point for gaining information on the chemical nature of the adlayer and, at present, RAIRS data has been collected on a range of complex adsorbates, including amino acids [65,80-82,88,92-97], nucleic acids [98,99], chiral modifiers [100-105], bicarboxyhc acids [101-106], and complex reactants such as esters [107,... 

---