Structural Dynamics (Mar 2015)

Vacuum space charge effects in sub-picosecond soft X-ray photoemission on a molecular adsorbate layer

  • M. Dell'Angela,
  • T. Anniyev,
  • M. Beye,
  • R. Coffee,
  • A. Föhlisch,
  • J. Gladh,
  • S. Kaya,
  • T. Katayama,
  • O. Krupin,
  • A. Nilsson,
  • D. Nordlund,
  • W. F. Schlotter,
  • J. A. Sellberg,
  • F. Sorgenfrei,
  • J. J. Turner,
  • H. Öström,
  • H. Ogasawara,
  • M. Wolf,
  • W. Wurth

DOI
https://doi.org/10.1063/1.4914892
Journal volume & issue
Vol. 2, no. 2
pp. 025101 – 025101-10

Abstract

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Vacuum space charge induced kinetic energy shifts of O 1s and Ru 3d core levels in femtosecond soft X-ray photoemission spectra (PES) have been studied at a free electron laser (FEL) for an oxygen layer on Ru(0001). We fully reproduced the measurements by simulating the in-vacuum expansion of the photoelectrons and demonstrate the space charge contribution of the high-order harmonics in the FEL beam. Employing the same analysis for 400 nm pump-X-ray probe PES, we can disentangle the delay dependent Ru 3d energy shifts into effects induced by space charge and by lattice heating from the femtosecond pump pulse.