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@ARTICLE{Engel:449355,
      author       = {Engel, Robin and Miedema, Piter S. and Turenne, Diego and
                      Vaskivskyi, Igor and Brenner, Günter and Dziarzhytski,
                      Siarhei and Kuhlmann, Marion and Schunck, Jan O. and
                      Döring, Florian and Styervoyedov, Andriy and Parkin, Stuart
                      S. P. and David, Christian and Schuessler-Langeheine,
                      Christian and Duerr, Hermann and Beye, Martin},
      title        = {{P}arallel {B}roadband {F}emtosecond {R}eflection
                      {S}pectroscopy at a {S}oft {X}-{R}ay {F}ree-{E}lectron
                      {L}aser},
      journal      = {Applied Sciences},
      volume       = {10},
      number       = {19},
      issn         = {2076-3417},
      address      = {Basel},
      publisher    = {MDPI},
      reportid     = {PUBDB-2020-03739},
      pages        = {6947},
      year         = {2020},
      abstract     = {X-ray absorption spectroscopy (XAS) and the directly linked
                      X-ray reflectivity near absorption edges yield a wealth of
                      specific information on the electronic structure around the
                      resonantly addressed element. Observing the dynamic response
                      of complex materials to optical excitations in pump–probe
                      experiments requires high sensitivity to small changes in
                      the spectra which in turn necessitates the brilliance of
                      free electron laser (FEL) pulses. However, due to the
                      fluctuating spectral content of pulses generated by
                      self-amplified spontaneous emission (SASE), FEL experiments
                      often struggle to reach the full sensitivity and
                      time-resolution that FELs can in principle enable. Here, we
                      implement a setup which solves two common challenges in this
                      type of spectroscopy using FELs: First, we achieve a high
                      spectral resolution by using a spectrometer downstream of
                      the sample instead of a monochromator upstream of the
                      sample. Thus, the full FEL bandwidth contributes to the
                      measurement at the same time, and the FEL pulse duration is
                      not elongated by a monochromator. Second, the FEL beam is
                      divided into identical copies by a transmission grating beam
                      splitter so that two spectra from separate spots on the
                      sample (or from the sample and known reference) can be
                      recorded in-parallel with the same spectrometer, enabling a
                      spectrally resolved intensity normalization of pulse
                      fluctuations in pump–probe scenarios. We analyze the
                      capabilities of this setup around the oxygen K- and nickel
                      L-edges recorded with third harmonic radiation of the free
                      electron laser in Hamburg (FLASH), demonstrating the
                      capability for pump–probe measurements with sensitivity to
                      reflectivity changes on the per mill level.},
      cin          = {FS-FLASH / DOOR ; HAS-User / FS-FLASH-B / FS-FLASH-O},
      ddc          = {600},
      cid          = {I:(DE-H253)FS-FLASH-20140814 / I:(DE-H253)HAS-User-20120731
                      / I:(DE-H253)FS-FLASH-B-20160930 /
                      I:(DE-H253)FS-FLASH-O-20160930},
      pnm          = {6211 - Extreme States of Matter: From Cold Ions to Hot
                      Plasmas (POF3-621) / 6G2 - FLASH (POF3-622) / FS-Proposal:
                      F-20180568 (F-20180568) / VH-NG-1105 - Novel soft X-ray
                      spectroscopies for materials science
                      $(2016_IVF-VH-NG-1105)$},
      pid          = {G:(DE-HGF)POF3-6211 / G:(DE-HGF)POF3-6G2 /
                      G:(DE-H253)F-20180568 / $G:(DE-HGF)2016_IVF-VH-NG-1105$},
      experiment   = {EXP:(DE-H253)F-FL24-20150901},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000587186100001},
      doi          = {10.3390/app10196947},
      url          = {https://bib-pubdb1.desy.de/record/449355},
}