Solidification and Phase Transition of Simple Molecule under Rapidly Modulating Pressure

Understanding the structural evolution and kinetics of phase transitions under dynamic compression has been an active area of research for many decades. Primarily, these studies have used either gas guns or lasers to drive the sample at high strain rates. Relatively recent development of piezo-electric-actuator driven dynamic- diamond anvil cells (d-DAC) can bridge the strain rate gap between traditional static DAC and shock compression studies. Coupling with the 3G(synchrotron) and 4G(XFEL) X-rays and time-resolved (TR) optical and spectroscopic probes, d-DAC is now capable to probe the time-evolution of crystal structure and chemical bonding under dynamic loadings to 10³/sec. The study in this intermediate strain rate regime is important, not only to complement conventional static (<10^-1/s) and shock wave (>10⁵/s) experiments along nearly isothermal compression pathways, but also because the diffusion process in dense fluid and solid occurs in this time scale (µs to ms). In this talk, following a brief description of recent technology development amid d-DAC and various TR probes, we will describe our recent efforts of d-DAC to investigate (1) crystallization and growth of H₂, D₂, and H₂O and (2) phase transitions of N₂ under rapidly modulating pressures. 

 

* A part of this work has been performed in collaboration with Z. Jenei, E. O’bannon, W. Evans at LLNL; B. Sturevent, D. Dattelbaum at LANL; and Z. Husband, H. P. Liermann at DESY. The work at WSU has been supported by the NSF(DMR 2112653) and DOE-NNSA(DE-NA0003918).