@article{LeverMayerMetjeetal.2021,
  author    = {Lever, Fabiano and Mayer, Dennis and Metje, Jan and Alisauskas, Skirmantas and Calegari, Francesca and D{\"u}sterer, Stefan and Feifel, Raimund and Niebuhr, Mario and Manschwetus, Bastian and Kuhlmann, Marion and Mazza, Tommaso and Robinson, Matthew Scott and Squibb, Richard J. and Trabattoni, Andrea and Wallner, M{\aa}ns and Wolf, Thomas J. A. and G{\"u}hr, Markus},
  title     = {Core-level spectroscopy of 2-thiouracil at the sulfur L1 and L2,3 edges utilizing a SASE free-electron-laser},
  series = {Molecules},
  volume    = {26},
  journal   = {Molecules},
  number    = {21},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1420-3049},
  pages     = {11},
  year      = {2021},
  abstract  = {In this paper, we report X-ray absorption and core-level electron spectra of the nucleobase derivative 2-thiouracil at the sulfur L1- and L2,3-edges. We used soft X-rays from the free-electron laser FLASH2 for the excitation of isolated molecules and dispersed the outgoing electrons with a magnetic bottle spectrometer. We identified photoelectrons from the 2p core orbital, accompanied by an electron correlation satellite, as well as resonant and non-resonant Coster-Kronig and Auger-Meitner emission at the L1- and L2,3-edges, respectively. We used the electron yield to construct X-ray absorption spectra at the two edges. The experimental data obtained are put in the context of the literature currently available on sulfur core-level and 2-thiouracil spectroscopy.},
  language  = {en}
}
@article{MayerLeverGuehr2022,
  author    = {Mayer, Dennis and Lever, Fabiano and G{\"u}hr, Markus},
  title     = {Data analysis procedures for time-resolved x-ray photoelectron spectroscopy at a SASE free-electron-laser},
  series = {Journal of physics : B, Atomic, molecular and optical physics},
  volume    = {55},
  journal   = {Journal of physics : B, Atomic, molecular and optical physics},
  number    = {5},
  publisher = {IOP Publ.},
  address   = {Bristol},
  issn      = {0953-4075},
  doi       = {10.1088/1361-6455/ac3c91},
  pages     = {9},
  year      = {2022},
  abstract  = {The random nature of self-amplified spontaneous emission (SASE) is a well-known challenge for x-ray core level spectroscopy at SASE free-electron lasers (FELs). Especially in time-resolved experiments that require a combination of good temporal and spectral resolution the jitter and drifts in the spectral characteristics, relative arrival time as well as power fluctuations can smear out spectral-temporal features. We present a combination of methods for the analysis of time-resolved photoelectron spectra based on power and time corrections as well as self-referencing of a strong photoelectron line. Based on sulfur 2p photoelectron spectra of 2-thiouracil taken at the SASE FEL FLASH2, we show that it is possible to correct for some of the photon energy drift and jitter even when reliable shot-to-shot photon energy data is not available. The quality of pump-probe difference spectra improves as random jumps in energy between delay points reduce significantly. The data analysis allows to identify coherent oscillations of 1 eV shift on the mean photoelectron line of 4 eV width with an error of less than 0.1 eV.},
  language  = {en}
}