@article{282106ed2b894bef9fe5e812afc91486,
title = "X-ray Emission Spectroscopy at X-ray Free Electron Lasers: Limits to Observation of the Classical Spectroscopic Response for Electronic Structure Analysis",
abstract = " X-ray free electron lasers (XFELs) provide ultrashort intense X-ray pulses suitable to probe electron dynamics but can also induce a multitude of nonlinear excitation processes. These affect spectroscopic measurements and interpretation, particularly for upcoming brighter XFELs. Here we identify and discuss the limits to observing classical spectroscopy, where only one photon is absorbed per atom for a Mn 2+ in a light element (O, C, H) environment. X-ray emission spectroscopy (XES) with different incident photon energies, pulse intensities, and pulse durations is presented. A rate equation model based on sequential ionization and relaxation events is used to calculate populations of multiply ionized states during a single pulse and to explain the observed X-ray induced spectral lines shifts. This model provides easy estimation of spectral shifts, which is essential for experimental designs at XFELs and illustrates that shorter X-ray pulses will not overcome sequential ionization but can reduce electron cascade effects.",
author = "Jensen, {Scott C.} and Brendan Sullivan and Hartzler, {Daniel A.} and Aguilar, {Jose Meza} and Salah Awel and Sa{\v s}a Bajt and Shibom Basu and Richard Bean and Chapman, {Henry N.} and Chelsie Conrad and Matthias Frank and Raimund Fromme and Martin-Garcia, {Jose M.} and Grant, {Thomas D.} and Michael Heymann and Hunter, {Mark S.} and Gihan Ketawala and Kirian, {Richard A.} and Juraj Knoska and Christopher Kupitz and Xuanxuan Li and Mengning Liang and Stella Lisova and Valerio Mariani and Victoria Mazalova and Marc Messerschmidt and Michael Moran and Garrett Nelson and Dominik Oberth{\"u}r and Alex Schaffer and Sierra, {Raymond G.} and Natalie Vaughn and Uwe Weierstall and Wiedorn, {Max O.} and Xavier, {P. Lourdu} and Yang, {Jay How} and Oleksandr Yefanov and Zatsepin, {Nadia A.} and Andrew Aquila and Petra Fromme and S{\'e}bastien Boutet and Seidler, {Gerald T.} and Yulia Pushkar",
note = "Funding Information: We acknowledge Marius Schmidt, Abbas Ourmazd, Ahmad Hosseinizadeh, and Peter Schwander for help in data collection during the two beamtimes. The experiments were carried out during beamtimes LJ49 and LL23 (PI Petra Fromme) at beamline CXI at the Linac Coherent Light Source, a national user facility operated by Stanford University on behalf of the US Department of Energy (DOE), Office of Basic Energy Sciences (OBES). Use of the Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. Parts of the sample delivery system used at LCLS for this research was funded by the NIH grant P41GM103393, formerly P41RR001209. This work was supported by the following agencies: the National Science Foundation, Division of Chemistry CHE-1350909 (Y.P.) the National Institutes of Health (award 1R01GM095583) (P.F.). This work was supported by the National Science Foundation (NSF)-Science and Technology Center (STC) “BioXFEL” through award STC-1231306, by funds from the National Institutes of Health grant R01 GM095583 as well as funds from the Biodesign Center for Applied Structural Discovery at Arizona State University. This work is also supported by the AXSIS project funded by the European Research Council under the European Union Seventh Framework Program (FP/2007-2013)/ERC Grant Agreement no. 609920. G.T.S. acknowledges support by the Joint Plasma Physics Program of the National Science Foundation and the Department of Energy under Grant No. DESC0016251. This work was performed, in part, under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. M.F. was supported by the NIH grant 1R01GM117342-01. Publisher Copyright: Copyright {\textcopyright} 2018 American Chemical Society.",
year = "2019",
month = feb,
day = "7",
doi = "10.1021/acs.jpclett.8b03595",
language = "English (US)",
volume = "10",
pages = "441--446",
journal = "Journal of Physical Chemistry Letters",
issn = "1948-7185",
publisher = "American Chemical Society",
number = "3",
}