Details

Autor(en) / Beteiligte

• Ranieri, Umbertoluca
• Klotz, Stefan
• Gaal, Richard
• Koza, Michael Marek
• Bove, Livia E.

Titel

Diffusion in dense supercritical methane from quasi-elastic neutron scattering measurements

Ist Teil von

• Nature communications, 2021-03, Vol.12 (1), p.1958-1958, Article 1958

Ort / Verlag

London: Nature Publishing Group UK

Erscheinungsjahr

2021

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Methane, the principal component of natural gas, is an important energy source and raw material for chemical reactions. It also plays a significant role in planetary physics, being one of the major constituents of giant planets. Here, we report measurements of the molecular self-diffusion coefficient of dense supercritical CH 4 reaching the freezing pressure. We find that the high-pressure behaviour of the self-diffusion coefficient measured by quasi-elastic neutron scattering at 300 K departs from that expected for a dense fluid of hard spheres and suggests a density-dependent molecular diameter. Breakdown of the Stokes–Einstein–Sutherland relation is observed and the experimental results suggest the existence of another scaling between self-diffusion coefficient D and shear viscosity η , in such a way that D η / ρ =constant at constant temperature, with ρ the density. These findings underpin the lack of a simple model for dense fluids including the pressure dependence of their transport properties. Methane is abundant in the Universe, is an important energy carrier and a model system for fundamental studies. Here, the authors measure the self-diffusion coefficient of supercritical methane at ambient temperature up to the freezing pressure, and find a different behavior than expected based on previous models.