Eur. Phys. J. Special Topics 196, 85-93 (2011)
https://doi.org/10.1140/epjst/e2011-01420-5

Regular Article

Transverse excitations in liquid Ga

¹ Center for Materials Research Using Third-Generation Synchrotron Radiation Facilities, Hiroshima Institute of Technology, Hiroshima 731-5193, Japan
² Physikalische Chemie, Fachbereich Chemie, Philipps Universiät Marburg, 35032 Marburg, Germany
³ Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521, Japan
⁴ Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
⁵ Department of Materials Science and Engineering, Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan
⁶ European XFEL GmbH, 22607 Hamburg, Germany
⁷ Departamento de Física Teórica, Universidad de Valladolid, 47011 Valladolid, Spain
⁸ SPring-8/JASRI, Hyogo 679-5198, Japan
⁹ RIKEN SPring-8 Center, Hyogo 679-5148, Japan

^a e-mail: hosokawa@cc.it-hiroshima.ac.jp

Received: 1 December 2010
Revised: 13 April 2011
Published online: 30 May 2011

Abstract

The transverse acoustic excitation modes were detected by inelastic x-ray scattering in liquid Ga in the Q range above 9 nm⁻¹ although liquid Ga is mostly described by a hard-sphere liquid. An ab initio molecular dynamics simulation clearly supports this finding. From the detailed analysis for the S(Q,ω) spectra with a good statistic quality, the lifetime of 0.5 ps and the propagating length of 0.4–0.5 nm can be estimated for the transverse acoustic phonon modes, which may correspond the lifetime and size of cages formed instantaneously in liquid Ga. The microscopic Poisson’s ratio estimated from the dynamic velocities of sound is 0.42, indicating a rubber-like soft elastic property of the cages.