Liquid Structure of Shock-Compressed Hydrocarbons at Megabar Pressures

N. J. Hartley, J. Vorberger, T. Döppner, T. Cowan, R. W. Falcone, L. B. Fletcher, S. Frydrych, E. Galtier, E. J. Gamboa, D. O. Gericke, S. H. Glenzer, E. Granados, M. J. MacDonald, A. J. MacKinnon, E. E. McBride, I. Nam, P. Neumayer, A. Pak, K. Rohatsch, A. M. Saunders, A. K. Schuster, P. Sun, T. van Driel, and D. Kraus

Phys. Rev. Lett. 121, 245501 – Published 14 December 2018

Abstract

We present results for the ionic structure in hydrocarbons (polystyrene, polyethylene) that were shock compressed to pressures of up to 190 GPa, inducing rapid melting of the samples. The structure of the resulting liquid is then probed using in situ diffraction by an x-ray free electron laser beam, demonstrating the capability to obtain reliable diffraction data in a single shot, even for low- $Z$ samples without long range order. The data agree well with ab initio simulations, validating the ability of such approaches to model mixed samples in states where complex interparticle bonds remain, and showing that simpler models are not necessarily valid. While the results clearly exclude the possibility of complete carbon-hydrogen demixing at the conditions probed, they also, in contrast to previous predictions, indicate that diffraction is not always a sufficient diagnostic for this phenomenon.

Received 4 May 2018
Revised 15 October 2018

DOI:https://doi.org/10.1103/PhysRevLett.121.245501

Physics Subject Headings (PhySH)

High-energy-density plasmas Plasma production & heating by shock waves & compression Shock waves

Carbon-based materials Liquids

Density functional theory X-ray diffraction

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

N. J. Hartley^1,2,*, J. Vorberger¹, T. Döppner³, T. Cowan^1,4, R. W. Falcone⁵, L. B. Fletcher⁶, S. Frydrych^7,3, E. Galtier⁶, E. J. Gamboa⁶, D. O. Gericke⁸, S. H. Glenzer⁶, E. Granados⁶, M. J. MacDonald^6,9, A. J. MacKinnon⁶, E. E. McBride^6,10, I. Nam⁶, P. Neumayer¹¹, A. Pak³, K. Rohatsch^1,4, A. M. Saunders⁵, A. K. Schuster^1,4, P. Sun⁶, T. van Driel⁶, and D. Kraus^1,4

¹Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany
²Open and Transdisciplinary Research Institute, Osaka University, Suita, Osaka 565-0871, Japan
³Lawrence Livermore National Laboratory, Livermore, California 94550, USA
⁴Technische Universität Dresden, 01062 Dresden, Germany
⁵Department of Physics, University of California, Berkeley, California 94720, USA
⁶SLAC National Accelerator Laboratory, Menlo Park, California 94309, USA
⁷Technische Universität Darmstadt, Schlossgartenstraße 9, 64289 Darmstadt, Germany
⁸Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
⁹University of Michigan, Ann Arbor, Michigan 48109, USA
¹⁰European XFEL GmbH, Holzkoppel 4, 22869 Schenefeld, Germany
¹¹GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt, Germany