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