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DOE OSTI · 3364823

Two-component dynamics in supercritical $\text {CO}_2$ from inelastic X-ray scattering

Abstract

Supercritical fluids are characterized by unique thermodynamic properties. One of these properties is the existence of two-component dynamics that is associated with distinct low-frequency and high-frequency vibrational responses of the fluid. However, the origin of this behavior remains unknown. By combining inelastic X-ray scattering and molecular dynamics simulations, we show that this behavior can be connected to density heterogeneities arising from molecular clusters. Analyses of measurements and molecular trajectories suggest that the two-component dynamics emerges due to distinct momentum fluctuations of clustered and unbound molecules. This connection between clusters and two-component dynamics highlights the importance of molecular-structural heterogeneities in supercritical fluids, colloids, and condensed-matter systems.

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BibTeXRIS

Majumdar, Arijit [Stanford Univ., CA (United States)], Sun, Peihao [Univ. degli Studi di Padova (Italy)], Singleton, Madison [Stanford Univ., CA (United States)], Paolasini, Luigi [European Synchrotron Radiation Facility (ESRF), Grenoble (France)], Bosak, Alexey [European Synchrotron Radiation Facility (ESRF), Grenoble (France)], Baron, Alfred Q. R. [RIKEN SPring-8 Center, Sayo (Japan)], Hastings, Jerome [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)], Ihme, Matthias [Stanford Univ., CA (United States); SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)]. 2026-02-11. Two-component dynamics in supercritical $\text {CO}_2$ from inelastic X-ray scattering. https://doi.org/10.1038/s41598-026-38697-z

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biophysics↗