The measurement of self-diffusion coefficients in liquid germanium using quasielastic neutron scattering
Henning Weis, Tobias Unruh and Andreas Meyer
We measured dynamic structure factors using quasielastic neutron scattering for two liquid germanium samples, one in natural isotope abundance, and a second one with a nat /73Ge isotope mixture which exhibits an order of magnitude larger ratio of incoherent to coherent neutron scattering cross section. In an intermediate q range corresponding spectra exhibit similar quasielastic broadening. We show that the measured quasielastic line originates from incoherent scattering. Coherent contributions appear as an almost energy independent background. From the incoherent quasielastic neutron scattering signal self-diffusion coefficients can therefore accurately be derived..
Keywords: Liquid germanium, atomic self diffusion, thermal diffusion, phonon dispersion, neutron scattering, X-ray scattering, coherent and incoherent scattering, Rayleigh line, Brillouin lines.