Inelastic neutron scattering , hydrogen

Role of adsorbed hydrogen species on ruthenium and molybdenum sulfides. Characterization by inelastic neutron scattering, thermoanalysis methods and model reactions. 

Supplementary to other vibrational spectroscopies, inelastic neutron scattering (INS) spectroscopy is a very useful technique for studying organic molecules as it is extremely sensitive to the vibrations of hydrogen atoms. INS spectroscopy has been used to analyze the molecular dynamics of the energetic compound ANTA 5 <2005CPL(403)329>. 

The usefulness of potential energy hypersurfaces in describing reaction dynamics and chemical reactivity is well illustrated by Levine and Bernstein [84] and Shaik et al. [85] books. See also the fundamental paper of Hase [86]. This success does not assure that the coordinate representation of quantum system is necessarily truthful. It goes without saying, the coordinate representation is an extremely useful mathematical model. However, from recent inelastic neutron scattering experiments on hydrogen bonded system, the idea that the BO approximation may be inadequate has been advanced by Kearley and coworkers[87]. 

Parker, S.F., Taylor, J.W., Albers, R, Lopez, M., Sextl, G., Lennon, D., Mclnroy, A.R., Sutherland, I.W. 2004. Inelastic neutron scattering studies of hydrogen on fuel cell catalysts. Vibration Spectrosc 35 179-182. 

Palladium black is another transition metal subsTrate on which hydrogen chemisorption has been studied by inelastic neutron scattering (33). Two bands were observed at 916 cm-1 and 823 cm"1 which were assigned to vibrations of the hydrogen parallel and perpendicular to the surface, respectively. A bridge site was inferred based on the number of modes observed without making any assumptions about the expected excitation frequencies for the different site geometries. 

Adsorbed hydrogen on metal surfaces is of particular interest from both theoretical and experimental points of view. Vibrational spectroscopy data on hydrogen adsorbed from the gas phase have been obtained from IR reflection-absorption experiments as well as from electron energy loss spectroscopy and inelastic neutron scattering techniques [39-41]. In UHV, absorption bands for the M-H bond have been reported in the mid- and far-infrared regions [41, 42],... 

Inelastic neutron scattering studies have shown [7-11] that many hydrogen-bonded crystals [potassium carbonate (i.e., KHCO3), various polyanilines, Ca(OH)2, and others] are characterized by the proton dynamics that is very decoupled from the backbone lattice. 

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