Issue
EPL
Volume 79, Number 1, July 2007
Article Number 16002
Number of page(s) 5
Section Condensed Matter: Structural, Mechanical and Thermal Properties
DOI http://dx.doi.org/10.1209/0295-5075/79/16002
Published online 07 June 2007
EPL, 79 (2007) 16002
DOI: 10.1209/0295-5075/79/16002

Evidence for the coexistence of two density fluctuation modes in molten Li30Bi70 as probed by neutron scattering

L. E. Bove1, F. Formisano2, E. Guarini3, 4, A. Ivanov5, C. Petrillo4, 6 and F. Sacchetti4, 6

1  Département Physique des Milieux Denses CNRS-IMPMC, Université Paris 6 F-75015 Paris, France
2  CNR-INFM CRS-Soft, c/o Institut Laue-Langevin - BP 156, F-38042 Grenoble, France
3  Dipartimento di Fisica, Università di Firenze - I-50019 Sesto Fiorentino, Italy
4  CNR-INFM CRS-Soft, Roma, Italy
5  Institut Laue Langevin - BP 156, F-38042 Grenoble, France
6  Dipartimento di Fisica, Università di Perugia - I-06123 Perugia, Italy


received 7 November 2006; accepted in final form 21 May 2007; published July 2007
published online 7 June 2007

Abstract
We report on a novel simultaneous observation of two inelastic doublets in the dynamic structure factor of the liquid alloy Li30Bi70. This result establishes the coexistence of two density fluctuation modes in a liquid binary system with disparate mass components. The measurements of the dynamic structure factor of the alloy have been performed on the hot neutron three-axis spectrometer IN1 of the Institut Laue-Langevin with an unprecedented energy resolution in the small wave vector domain. Analysis of the dynamical parameters characterizing the two excitations reveals the acoustic nature of the low-frequency mode and suggests an optic-like nature for the high-frequency mode. A comparison with recent neutron scattering results on pure liquid Bi suggests that the low-frequency mode in the alloy is closely related to the heavier component dynamics.

PACS
61.12.Ex - Neutron scattering (including small-angle scattering).
63.50.+x - Vibrational states in disordered systems.
78.35.+c - Brillouin and Rayleigh scattering; other light scattering.

© Europhysics Letters Association 2007