High-pressure behavior of the D₂/H₂-CO₂ system

Investigating the D₂/H₂-CO₂ system is essential for constraining the intermolecular interactions, pressure-induced chemistry, and phase behavior of one of the most fundamental mixtures in earth and planetary science. Recent high-pressure experiments on different compositions of D₂/H₂-CO₂ were analyzed using the diamond anvil cell to constrain the initial pressure-density state for precompressed dynamic compression experiments. The ρ-P acoustic velocities were measured with Brillouin spectroscopy, which revealed interesting phase behavior. The system's phase behavior and chemical changes were further explored using Raman and infrared spectroscopies and compared with first-principles calculations. These results demonstrate the richness of the little-studied H₂-CO₂ system and help establish a physical and chemical picture for future high P-T shock-ramp compression experiments.