title: X-ray scattering measurements of dissociation-induced metallization of dynamically compressed deuterium.
abstract: Hydrogen, the simplest element in the universe, has a surprisingly complex phase diagram. Because of applications to planetary science, inertial confinement fusion and fundamental physics, its high-pressure properties have been the subject of intense study over the past two decades. While sophisticated static experiments have probed hydrogen's structure at ever higher pressures, studies examining the higher-temperature regime using dynamic compression have mostly been limited to optical measurement techniques. Here we present spectrally resolved x-ray scattering measurements from plasmons in dynamically compressed deuterium. Combined with Compton scattering, and velocity interferometry to determine shock pressure and mass density, this allows us to extract ionization state as a function of compression. The onset of ionization occurs close in pressure to where density functional theory-molecular dynamics (DFT-MD) simulations show molecular dissociation, suggesting hydrogen transitions from a molecular and insulating fluid to a conducting state without passing through an intermediate atomic phase.
authors.affiliation: University of California, Berkeley, California 94720, USA.|Lawrence Livermore National Laboratory, PO Box 808, Livermore, California 94551, USA.
authors.forename: P
authors.initials: P
authors.lastname: Davis
authors.affiliation: Lawrence Livermore National Laboratory, PO Box 808, Livermore, California 94551, USA.
authors.forename: T
authors.initials: T
authors.lastname: Döppner
authors.affiliation: Lawrence Livermore National Laboratory, PO Box 808, Livermore, California 94551, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Rygg
authors.affiliation: Lawrence Livermore National Laboratory, PO Box 808, Livermore, California 94551, USA.|University of California, Los Angeles, California 90095, USA.
authors.forename: C
authors.initials: C
authors.lastname: Fortmann
authors.affiliation: Lawrence Livermore National Laboratory, PO Box 808, Livermore, California 94551, USA.
authors.forename: L
authors.initials: L
authors.lastname: Divol
authors.affiliation: Lawrence Livermore National Laboratory, PO Box 808, Livermore, California 94551, USA.
authors.forename: A
authors.initials: A
authors.lastname: Pak
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: L
authors.initials: L
authors.lastname: Fletcher
authors.affiliation: Institut für Physik, Universität Rostock, D-18051 Rostock, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Becker
authors.affiliation: Institut für Physik, Universität Rostock, D-18051 Rostock, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Holst
authors.affiliation: Institut für Physik, Universität Rostock, D-18051 Rostock, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Sperling
authors.affiliation: Institut für Physik, Universität Rostock, D-18051 Rostock, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Redmer
authors.affiliation: Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
authors.forename: M P
authors.initials: MP
authors.lastname: Desjarlais
authors.affiliation: Lawrence Livermore National Laboratory, PO Box 808, Livermore, California 94551, USA.
authors.forename: P
authors.initials: P
authors.lastname: Celliers
authors.affiliation: Lawrence Livermore National Laboratory, PO Box 808, Livermore, California 94551, USA.
authors.forename: G W
authors.initials: GW
authors.lastname: Collins
authors.affiliation: Lawrence Livermore National Laboratory, PO Box 808, Livermore, California 94551, USA.
authors.forename: O L
authors.initials: OL
authors.lastname: Landen
authors.affiliation: University of California, Berkeley, California 94720, USA.
authors.forename: R W
authors.initials: RW
authors.lastname: Falcone
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: S H
authors.initials: SH
authors.lastname: Glenzer