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Articles you may be interested inRole of distortion in the hcp vs fcc competition in rare-gas solids Low Temp. Phys. 37, 435 (2011); 10.1063/1.3606459 Broadband rotational resonance in solid state NMR spectroscopy Comment on the stability of fcc and hcp hardsphere solids J. Chem. Phys. 82, 5760 (1985); 10.1063/1.448567 NMR relaxation rate and the libron energy of solid hydrogenTransitions between the rotational states J = 1 and J =0 and the densities of phonon and libron states are investigated by incoherent inelastic neutron scattering at 4.2 and at 1.15°K for several concentrations e of the ortho component. By extrapolation of the observed c-dependent energy of the J = 1 state to c=O and c= 1 the effective quadrupole-quadrupole coupling constant is determined. The observations on the densities of phonon and libron states are compared to theoretical predictions.

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Inelastic coherent neutron scattering is called Brillouin scattering, if the momentum transferred to the scattering system is entirely taken up by collective particle motions. With this scattering, single excited states of such motions can be observed in polycrystals and in liquids in a similar way as in single crystals, provided the measurements are not too much contaminated by multiple scattering processes combining Bragg and inelastic scattering. Liquid and solid lead are investigated in this way. The comparison of the measured dispersion laws shows that at 340°C, for frequencies between 6-4 x 1011 and 2.3 x 1012 sec-1 and wavelengths between 7 and 21 A, sound waves propagate in the liquid by the same mechanism as in the solid. The contaminating double scattering is predominantly determined by maxima in the distribution of frequencies of collective motions. The observed positions of such maxima indicate that transverse modes exist also in the liquid.