Observation of propagating collective excitations in liquid SO2

摘要

The spectrum of collective excitations in liquid sulphur dioxide at two thermodynamic states has been measured by neutron triplehyphen;axis spectroscopy for momentum transfer ranges of 0.35le;Qle;2.0 Aring;minus;1. Wellhyphen;resolved inelastic peaks indicating the presence of propagating modes are found forQvalues below 0.5 Aring;minus;1atT=266 K and below 0.7 Aring;minus;1atT=210 K. A precise value for the hydrodynamic limit has been found in both cases and the measured lsquo;lsquo;dispersion relationsrsquo;rsquo; are discussed in relation to predictions made by recent theoretical approaches.