Coherent excitations in liquid deuterium

The coherent dynamical response of liquid deuterium 0.5 K above the melting temperature has been studied by means of triple-axis inelastic scattering and time-of-flight techniques. A model scattering law to represent the single-particle and low-energy collective dynamics has been tested by analysing the time-of-flight spectra. On the other hand, well defined collective excitations up to a momentum transfer of 3.8 A-1 have been found in the triple-axis experiments. The derived dispersion curve shows a well defined minimum at 2.08 A-1 with a gap of 30 K. (orig.)