title: Nanoplasma Formation by High Intensity Hard X-rays.
abstract: Using electron spectroscopy, we have investigated nanoplasma formation from noble gas clusters exposed to high-intensity hard-x-ray pulses at ~5 keV. Our experiment was carried out at the SPring-8 Angstrom Compact free electron LAser (SACLA) facility in Japan. Dedicated theoretical simulations were performed with the molecular dynamics tool XMDYN. We found that in this unprecedented wavelength regime nanoplasma formation is a highly indirect process. In the argon clusters investigated, nanoplasma is mainly formed through secondary electron cascading initiated by slow Auger electrons. Energy is distributed within the sample entirely through Auger processes and secondary electron cascading following photoabsorption, as in the hard x-ray regime there is no direct energy transfer from the field to the plasma. This plasma formation mechanism is specific to the hard-x-ray regime and may, thus, also be important for XFEL-based molecular imaging studies. In xenon clusters, photo- and Auger electrons contribute more significantly to the nanoplasma formation. Good agreement between experiment and simulations validates our modelling approach. This has wide-ranging implications for our ability to quantitatively predict the behavior of complex molecular systems irradiated by high-intensity hard x-rays.
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Tachibana
authors.affiliation: 1] Center for Free-Electron Laser Science (CFEL), DESY, 22607 Hamburg, Germany [2] The Hamburg Centre for Ultrafast Imaging, 22761 Hamburg, Germany.
authors.forename: Z
authors.initials: Z
authors.lastname: Jurek
authors.affiliation: 1] Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan [2] RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Fukuzawa
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Motomura
authors.affiliation: 1] RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan [2] Department of Physics, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nagaya
authors.affiliation: 1] RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan [2] Department of Physical Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Wada
authors.affiliation: Department of Physics, Lund University, P.O. Box 118, 22100 Lund, Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Johnsson
authors.affiliation: Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom.
authors.forename: M
authors.initials: M
authors.lastname: Siano
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Mondal
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Ito
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kimura
authors.affiliation: Department of Physics, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Sakai
authors.affiliation: Department of Physics, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Matsunami
authors.affiliation: Department of Physical Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Hayashita
authors.affiliation: Department of Physical Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Kajikawa
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, FR-91192 Gif-sur-Yvette Cedex, France.
authors.forename: X-J
authors.initials: XJ
authors.lastname: Liu
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, FR-91192 Gif-sur-Yvette Cedex, France.
authors.forename: E
authors.initials: E
authors.lastname: Robert
authors.affiliation: 1] Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, FR-91192 Gif-sur-Yvette Cedex, France [2] Extreme Light Infrastructure - Nuclear Physics (ELI-NP), "Horia Hulubei" National Institute for Physics and Nuclear Engineering, 30 Reactorului Street, RO-077125 Măgurele, Jud. Ilfov, Romania.
authors.forename: C
authors.initials: C
authors.lastname: Miron
authors.affiliation: 1] Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala, Sweden [2] Department of Physics, University of Gothenburg, SE-412 96 Gothenburg, Sweden.
authors.forename: R
authors.initials: R
authors.lastname: Feifel
authors.affiliation: Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom.
authors.forename: J P
authors.initials: JP
authors.lastname: Marangos
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI), Sayo, Hyogo 679-5198, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tono
authors.affiliation: RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Inubushi
authors.affiliation: RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yabashi
authors.affiliation: 1] Center for Free-Electron Laser Science (CFEL), DESY, 22607 Hamburg, Germany [2] The Hamburg Centre for Ultrafast Imaging, 22761 Hamburg, Germany.
authors.forename: S-K
authors.initials: SK
authors.lastname: Son
authors.affiliation: 1] Center for Free-Electron Laser Science (CFEL), DESY, 22607 Hamburg, Germany [2] The Hamburg Centre for Ultrafast Imaging, 22761 Hamburg, Germany [3] Institute of Nuclear Physics, PAS, Radzikowskiego 152, 31-342, Krakow, Poland.
authors.forename: B
authors.initials: B
authors.lastname: Ziaja
authors.affiliation: Department of Physics, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yao
authors.affiliation: 1] Center for Free-Electron Laser Science (CFEL), DESY, 22607 Hamburg, Germany [2] The Hamburg Centre for Ultrafast Imaging, 22761 Hamburg, Germany [3] Department of Physics, University of Hamburg, 20355 Hamburg, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Santra
authors.affiliation: 1] Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan [2] RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ueda