학술논문
Speed of sound in methane under conditions of planetary interiors
Document Type
Working Paper
Author
White, Thomas G.; Poole, Hannah; McBride, Emma E.; Oliver, Matthew; Descamps, Adrien; Fletcher, Luke B.; Angermeier, W. Alex; Allen, Cameron H.; Appel, Karen; Condamine, Florian P.; Curry, Chandra B.; Dallari, Francesco; Funk, Stefan; Galtier, Eric; Gamboa, Eliseo J.; Gauthier, Maxence; Graham, Peter; Goede, Sebastian; Haden, Daniel; Kim, Jongjin B.; Lee, Hae Ja; Ofori-Okai, Benjamin K.; Richardson, Scott; Rigby, Alex; Schoenwaelder, Christopher; Sun, Peihao; Witte, Bastian L.; Tschentscher, Thomas; Zastrau, Ulf; Nagler, Bob; Hastings, J. B.; Monaco, Giulio; Gericke, Dirk O.; Glenzer, Siegfried H.; Gregori, Gianluca
Source
Physical Review Research 6 (2024) L022029
Subject
Language
Abstract
We present direct observations of acoustic waves in warm dense matter. We analyze wave-number- and energy-resolved x-ray spectra taken from warm dense methane created by laser heating a cryogenic liquid jet. X-ray diffraction and inelastic free-electron scattering yield sample conditions of 0.3$\pm$0.1 eV and 0.8$\pm$0.1 g/cm$^3$, corresponding to a pressure of $\sim$13 GPa. Inelastic x-ray scattering was used to observe the collective oscillations of the ions. With a highly improved energy resolution of $\sim$50 meV, we could clearly distinguish the Brillouin peaks from the quasielastic Rayleigh feature. Data at different wave numbers were utilized to derive a sound speed of 5.9$\pm$0.5 km/s, marking a high-temperature data point for methane and demonstrating consistency with Birch's law in this parameter regime.
Comment: 7 pages, 4 figures
Comment: 7 pages, 4 figures