X-ray free electron laser heating of water and gold at high static pressure

Rachel J Husband,Malcolm I Mcmahon,Jinhyuk Choi,Sang-Heon Shim,Orianna B Ball,Vitali B Prakapenka,Hyunchae Cynn,Sae Hwan Chun,Amy L Coleman,Hanns-Peter Liermann,Sangsoo Kim,Edward J Pace,Gil Chan Hwang,Taehyun Kim,Yongjae Lee,Sven Toleikis,R Stewart Mcwilliams,Daewoong Nam,Huijeong Hwang

doi:10.1038/s43246-021-00158-7

Abstract

Probing of reactive materials such as H2O ices and fluids at the high pressures and temperatures of planetary interiors is limited by unwanted chemical reactions and confinement failure. Faster experiments can mitigate such issues, but the common approach of adiabatic compression limits the conditions achieved. This study demonstrates a fast experimental strategy for the creation and probing of selected extreme states using static compression coupled with ultrafast X-ray laser heating. Indirect X-ray heating of H2O through the use of a gold absorber is evidenced by sample melting inferred from textural changes in the H2O diffraction lines and inter-dispersion of gold and H2O melts. Coupled with numerical analysis of femtosecond energy absorption, thermal equilibration, and heat transfer, all evidence indicates that temperatures in excess of an electron volt have been reached in the H2O at high pressure. Even after repeated heating, samples stayed chemically unchanged from the starting material.

Highlights

Probing of reactive materials such as H2O ices and fluids at the high pressures and temperatures of planetary interiors is limited by unwanted chemical reactions and confinement failure
We report the results of XFEL irradiation and X-ray diffraction experiments of statically compressed H2O samples performed at the Pohang Accelerator Laboratory XFEL (PALXFEL), South Korea, using an Au foil loaded along with the sample to absorb the XFEL beam
During the first PAL-XFEL experiment, data were collected on two samples of H2O and Au using an X-ray energy of 12 keV

Summary

Introduction

Probing of reactive materials such as H2O ices and fluids at the high pressures and temperatures of planetary interiors is limited by unwanted chemical reactions and confinement failure. A major challenge when studying the phase relations and physical properties of such compounds at simultaneous high P and T relates to their highly reactive nature at these conditions, especially in the molten state This is challenging for studies performed using diamond-anvil cells (DACs), where reactions between H2O with the gasket material (typically Re) introduces the possibility of cross-contamination of the sample material. These challenges have limited the conditions accessible to static-compression studies. Optical laser techniques (typically performed in the near-IR) are susceptible to unpredictable or limited heating, controlled by sample optical properties and restrictions on deliverable energy (e.g., through the anvils). This raises the prospect of utilizing pulsed X-ray laser heating from X-

Methods

Results

Conclusion