Crossover between hydrodynamic and kinetic modes in binary liquid alloys
arXiv:0803.0493 · doi:10.1103/PhysRevB.77.094204
Abstract
Inelastic x-ray scattering (IXS) measurements of the dynamic structure factor in liquid Na57K43, sensitive to the atomic-scale coarse graining, reveal a sound velocity value exceeding the long wavelength, continuum value and indicate the coexistence of two phonon-like modes. Applying Generalized Collective Mode (GCM) analysis scheme, we show that the positive dispersion of the sound velocity occurs in a wavelength region below the crossover from hydrodynamic to atom-type excitations and, therefore, it can not be explained as sound propagation over the light specie (Na) network. The present result experimentally proves the existence of positive dispersion in a binary mixture due to a relaxation process, as opposed to fast sound phenomena.
7 pages, 8 figures, to appear in "Physical Review B"
References in corpus (6)
- Microscopic dynamics in liquid metals: the experimental point of view
- Relaxation processes in harmonic glasses?
- Structural and Microscopic Relaxation Processes in Liquid Hydrogen Fluoride
- Evidence of short time dynamical correlations in simple liquids
- Viscoelastic model for the dynamic structure of binary systems
- Dynamic structure of He-Ne mixtures by MD simulation: from hydrodynamic to fast and slow sound modes