Speaker
Dr
Joanna Hoszowska
(Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland)
Description
We report on multiphoton processes involving inner-shell electrons of solid Fe with very intense and ultra-short hard x-ray free-electron laser (XFEL) pulses. The experiment was carried out at the CXI end-station of the Linac Coherent Light Source by means of the high energy resolution x-ray emission technique. The XFEL beam of ~10^12 photons/pulse and pulse energy in the range of 1-4 mJ was focused on the solid Fe sample. The ultra-focused x-ray beam provided an extreme fluence (~10^4-10^5 photons/Å^2). Moving the sample out of the focus along the beam allowed varying the fluence. For the K x-ray emission spectra measurements the bent crystal von Hamos x-ray spectrometer of PSI [1] installed at CXI and equipped with the CSPAD detector developed at SLAC was employed.
To explore the nonlinear interaction of Fe atoms with high-fluence XFEL radiation the photon beam energies were chosen below the Fe K-shell single- and double-ionization thresholds. The K x-ray emission spectra comprising the Kα (K^{-1}-->L^{-1}) diagram lines and the rich satellite structures due to the multiphoton induced multiple ionization, as well as the Kα^h hypersatellite (K^{-2}-->K^{-1}L^{-1}) transitions, were measured as a function of the XFEL fluence. The obtained results evince the nonlinear two-photon processes leading to K-shell ionization, and the K-shell hollow atom formation following sequential two-photon absorption.
[1] J. Szlachetko et al., Rev. Sci. Instrum. 83, 2012, 103105.
Primary author
Dr
Joanna Hoszowska
(Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland)
Co-authors
Prof.
Bruce Patterson
(Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland)
Dr
Christian David
(Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland)
Dr
Christopher Milne
(Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland)
Prof.
Christopher. T. Chantler
(School of Physics, University of Melbourne, Parkville, Victoria 3010, Australia)
Dr
Garth Williams
(Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, 94025 California, USA)
Dr
Grigory Smolentsev
(Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland)
Dr
Jacinto De Paiva Sa
(Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland)
Dr
Jakub Szlachetko
(Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland)
Prof.
Jean-Claude Dousse
(Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland)
Dr
Maarten Nachtegaal
(Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland)
Dr
Marc Messerschmidt
(Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, 94025 California, USA)
Prof.
Marek Pajek
(Institute of Physics, Jan Kochanowski University, 25-406 Kielce, Poland)
Dr
Rafael Abela
(Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland)
Dr
Sébastien Boutet
(Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, 94025 California, USA)
Mr
Wojciech Blachucki
(Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland)
Dr
Yves Kayser
(Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland)
