Inelastic neutron scattering metal vibrational mode

P.C.H. Mitchell, A.J. Ramirez-Cuesta, S.F. Parker, J. Tomkinson D. Thompsett (2003). J. Phys. Chem. B, 107, 6838-6845. Hydrogen spillover on carbon-supported metal catalysts studied by inelastic neutron scattering. Surface vibrational states and hydrogen riding modes. 

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. 

As we have described, a great deal of experimental data on the q 0 vibrational energy levels in the metal azides have been obtained in the last few years. A consistent picture of the internal and external modes in different azide lattices has emerged from these studies. The question of the degree of lattice ionicity in different azide lattices has been raised as a consequence of the available data, but needs detailed theoretical analysis. Particularly noteworthy has been the recent measurement by coherent neutron inelastic scattering of vibrational modes in different directions of the Brillouin zone in a metal azide crystal—KNa- More sophisticated analyses of diffraction data have now yielded precise inter- and intraionic bond lengths, thermal amplitudes of azide ion motions and, most recently, the valence electron density about N3 in KN3, all of which provide important additional input for the characterization of interatomic forces in azides. 

---