Studies of collective dynamics in liquid Ge over a wide temperature range using inelastic X-ray scattering technique

Our results for the dynamic structure factors S(Q, omega) of liquid Ge at 980degreesC and 1500degreesC obtained from inelastic X-ray scattering experiments, show distinct excitations resulting from propagating modes. The phonon dispersion matches the hydrodynamic sound velocity in the low Q range, i.e., no positive dispersion can be detected, which is consistent with generalized hydrodynamic theory. The similarity of our experimental results in S(Q, omega)s between 980degreesC and 1500degreesC and the absence of additional peaks besides the acoustic mode indicate no hint for internal vibrations in stable covalent clusters. (C) 2002 Elsevier Science B.V. All rights reserved.