Inelastic alumina

Korman CS, Lau JC, Johnson AM, Coleman RV (1979) Studies of aromatic-ring compounds adsorbed on alumina and magnesia using inelastic electron tunneling. Phys Rev B 19 994-1002... 

Inelastic electron tunneling spectroscopic studies of alkoxysilanes adsorbed on alumina... 

Abstract—Inelastic electron tunneling spectroscopy is used to investigate the adsorption of dimethyl-dimethoxysilane, dimethyldiethoxysilane, and dimethylvinylethoxy silane on alumina at the mono-layer level. Data obtained indicate that different adsorbed layers are produced when the silanes are introduced onto the oxide surface from solution or as a vapor. Silanes introduced in the same way onto different types of oxides suggest that alumina morphology also affects the adsorbed configuration. 

Due to the high density of Rh atoms, no species of the form Rh(C0)2 were formed, however. This is expected to be the case on the (111) surface as well. Weak absorptions between 400 and 575 cm"l were seen and are indicative of metal-absorbate stretching and bending vibrations. Inelastic electron tunneling spectroscopic (IETS) measurements on alumina supported rhodium particles (47, 48, 49) add little new structural information... 

Although not exhaustive, the above summary of experiments with hydrogen chemisorbed on transition-metals serves to illustrate how neutron vibrational spectroscopy is performed with catalytic substrates and the methods used to analyze the inelastic neutron spectra. In concluding this section we note that the technique can be extended to supported catalysts such as in recent experiments with hydrogen adsorbed on both MoS and alumina supported MoSp (38). Also, as another indication of the variety of systems which can be studied, we note earlier experiments with ethylene (39) and acetylene (40) adsorbed on silver exchanged 13X zeolites. "Tn this work, deuteration of the molecules was helpful in identifying the surface vibratory modes on these ionic substrates of greater complexity. 

Modern inelastic neutron scattering technique has made it possible to discover free protons in solids [49] that is, free protons have been found in manganese dioxides, coals, graphite nitric acid intercalation compounds, polypyrolles and polyanilines, and fi-alumina. Perhaps the said compounds may be called protonic conductors as well, though in the solids the density of free protons is very small and the distribution of proton kinetic momentum is hidden by the zero-point oscillations of the host matrix [49]. 

P.C.H. Mitchell, J. Tomkinson, J.G. Grimblot E. Payen (1993). J. Chem. Soc. Faraday Trans., 89, 1805-1807. Bound water in aged molybdate/alumina hydrodesulfiirisation catalysts an inelastic neutron scattering study. 

P. Sundberg, R.B. Moyes J. Tomkinson (1991). Bull. Soc. Chim. Belg., 100, 967-976. Inelastic neutron scattering spectroscopy of hydrogen adsorbed on powdered-MoS2, M0S2 -alumina and nickel-promoted M0S2,... 

Spectroscopic methods - infrared (IR) and Raman spectroscopy, NMR, and inelastic neutron scattering - have been very effective to identify protonic species and determine their configurations ". The IR spectra of the O-H stretching mode should be strong (Fig. 23.2) when the electric vector of the incident beam is normal to the c-axis E J. c) It is not clear in the literature, however, which are genuine spectra of H P-alumina and which are spectra of hydrated P-alumina. This confusion is caused partly by difficulty in preparing pure and unhydrated specimens. It is almost impossible to make pure P-alumina free from... 

The structurally related ri-form has received less study [58,59] but in both cases it has been concluded that three different types of surface Lewis site - strong, medium, and weak - are present. Our initial examinations (Figures 7.7 and 7.8) of activated tj-alumina, by observing desorption of a saturated chemisorbed py overlayer, through diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) observation of the py 8a mode band intensity at various temperatures, were in accord with this view [60]. The application of inelastic... 

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