@article{HantschmannFoehlisch2022,
  author    = {Hantschmann, Markus and F{\"o}hlisch, Alexander},
  title     = {A rate model approach for FEL pulse induced transmissions changes, saturable absorption, X-ray transparency and stimulated emission},
  series = {Journal of electron spectroscopy and related phenomena : the international journal on theoretical and experimental aspects of electron spectroscopy},
  volume    = {256},
  journal   = {Journal of electron spectroscopy and related phenomena : the international journal on theoretical and experimental aspects of electron spectroscopy},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0368-2048},
  doi       = {10.1016/j.elspec.2021.147139},
  pages     = {9},
  year      = {2022},
  abstract  = {As the use of free electron laser (FEL) sources increases, so do the findings mentioning non-linear phenomena occurring at these experiments, such as saturable absorption, induced transparency and scattering breakdowns. These are well known among the laser community, but are still rarely understood and expected among the X-ray community and to date lack tools and theories to accurately predict the respective experimental parameters and results. We present a simple theoretical framework to access short X-ray pulse induced light- matter interactions which occur at intense short X-ray pulses as available at FEL sources. Our approach allows to investigate effects such as saturable absorption, induced transparency and scattering suppression, stimulated emission, and transmission spectra, while including the density of state influence relevant to soft X-ray spectroscopy in, for example, transition metal complexes or functional materials. This computationally efficient rate model based approach is intuitively adaptable to most solid state sample systems in the soft X-ray spectrum with the potential to be extended for liquid and gas sample systems as well. The feasibility of the model to estimate the named effects and the influence of the density of state is demonstrated using the example of CoPd transition metal systems at the Co edge. We believe this work is an important contribution for the preparation, performance, and understanding of FEL based high intensity and short pulse experiments, especially on functional materials in the soft X-ray spectrum.},
  language  = {en}
}
@article{KunnusRajkovicSchrecketal.2012,
  author    = {Kunnus, Kristjan and Rajkovic, Ivan and Schreck, Simon and Quevedo, Wilson and Eckert, Sebastian and Beye, Martin and Suljoti, Edlira and Weniger, Christian and Kalus, Christian and Gruebel, Sebastian and Scholz, Mirko and Nordlund, Dennis and Zhang, Wenkai and Hartsock, Robert W. and Gaffney, Kelly J. and Schlotter, William F. and Turner, Joshua J. and Kennedy, Brian and Hennies, Franz and Techert, Simone and Wernet, Philippe and F{\"o}hlisch, Alexander},
  title     = {A setup for resonant inelastic soft x-ray scattering on liquids at free electron laser light sources},
  series = {Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques},
  volume    = {83},
  journal   = {Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques},
  number    = {12},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {0034-6748},
  doi       = {10.1063/1.4772685},
  pages     = {8},
  year      = {2012},
  abstract  = {We present a flexible and compact experimental setup that combines an in vacuum liquid jet with an x-ray emission spectrometer to enable static and femtosecond time-resolved resonant inelastic soft x-ray scattering (RIXS) measurements from liquids at free electron laser (FEL) light sources. We demonstrate the feasibility of this type of experiments with the measurements performed at the Linac Coherent Light Source FEL facility. At the FEL we observed changes in the RIXS spectra at high peak fluences which currently sets a limit to maximum attainable count rate at FELs. The setup presented here opens up new possibilities to study the structure and dynamics in liquids.},
  language  = {en}
}
@article{BeyeFoehlisch2011,
  author    = {Beye, Martin and F{\"o}hlisch, Alexander},
  title     = {A soft X-ray approach to electron-phonon interactions beyond the Born-Oppenheimer approximation},
  series = {Journal of electron spectroscopy and related phenomena : the international journal on theoretical and experimental aspects of electron spectroscopy},
  volume    = {184},
  journal   = {Journal of electron spectroscopy and related phenomena : the international journal on theoretical and experimental aspects of electron spectroscopy},
  number    = {3-6},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0368-2048},
  doi       = {10.1016/j.elspec.2010.12.032},
  pages     = {313 -- 317},
  year      = {2011},
  abstract  = {With modern soft X-ray methods, the whole field of electron-phonon interactions becomes accessible directly in the ultrafast time domain with ultrashort pulsed X-ray sources, as well as in the energy domain through modern highly resolving spectrometers. The well-known core-hole clock approach plays an intermediate role, resolving energetic and temporal features at the same time. In this perspective paper, we review several experiments to illustrate the modern advances in the selective study of electron-phonon interactions as fundamentally determining ingredients for materials properties. We present the different complementary approaches that can be taken with soft X-ray methods to conquer this field beyond the Born-Oppenheimer approximation.},
  language  = {en}
}
@article{VazdaCruzErtanCoutoetal.2017,
  author    = {Vaz da Cruz, Vinicius and Ertan, Emelie and Couto, Rafael C. and Eckert, Sebastian and Fondell, Mattis and Dantz, Marcus and Kennedy, Brian and Schmitt, Thorsten and Pietzsch, Annette and Guimaraes, Freddy F. and {\AA}gren, Hans and Odelius, Michael and F{\"o}hlisch, Alexander and Kimberg, Victor},
  title     = {A study of the water molecule using frequency control over nuclear dynamics in resonant X-ray scattering},
  series = {Physical chemistry, chemical physics : a journal of European Chemical Societies},
  volume    = {19},
  journal   = {Physical chemistry, chemical physics : a journal of European Chemical Societies},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1463-9076},
  doi       = {10.1039/c7cp01215b},
  pages     = {19573 -- 19589},
  year      = {2017},
  abstract  = {In this combined theoretical and experimental study we report a full analysis of the resonant inelastic X-ray scattering (RIXS) spectra of H2O, D2O and HDO. We demonstrate that electronically-elastic RIXS has an inherent capability to map the potential energy surface and to perform vibrational analysis of the electronic ground state in multimode systems. We show that the control and selection of vibrational excitation can be performed by tuning the X-ray frequency across core-excited molecular bands and that this is clearly reflected in the RIXS spectra. Using high level ab initio electronic structure and quantum nuclear wave packet calculations together with high resolution RIXS measurements, we discuss in detail the mode coupling, mode localization and anharmonicity in the studied systems.},
  language  = {en}
}
@misc{VazdaCruzErtanCoutoetal.2017,
  author    = {Vaz da Cruz, Vinicius and Ertan, Emelie and Couto, Rafael C. and Eckert, Sebastian and Fondell, Mattis and Dantz, Marcus and Kennedy, Brian and Schmitt, Thorsten and Pietzsch, Annette and Guimar{\~a}es, Freddy F. and {\AA}gren, Hans and Gel'mukhanov, Faris and Odelius, Michael and F{\"o}hlisch, Alexander and Kimberg, Victor},
  title     = {A study of the water molecule using frequency control over nuclear dynamics in resonant X-ray scattering},
  series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  number    = {781},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-43690},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-436901},
  pages     = {19573 -- 19589},
  year      = {2017},
  abstract  = {In this combined theoretical and experimental study we report a full analysis of the resonant inelastic X-ray scattering (RIXS) spectra of H2O, D2O and HDO. We demonstrate that electronically-elastic RIXS has an inherent capability to map the potential energy surface and to perform vibrational analysis of the electronic ground state in multimode systems. We show that the control and selection of vibrational excitation can be performed by tuning the X-ray frequency across core-excited molecular bands and that this is clearly reflected in the RIXS spectra. Using high level ab initio electronic structure and quantum nuclear wave packet calculations together with high resolution RIXS measurements, we discuss in detail the mode coupling, mode localization and anharmonicity in the studied systems.},
  language  = {en}
}
@article{ThielemannKuehnHoffmannFoehlisch2012,
  author    = {Thielemann-K{\"u}hn, Nele and Hoffmann, P. and F{\"o}hlisch, Alexander},
  title     = {A versatile detector for total fluorescence and electron yield experiments},
  series = {Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques},
  volume    = {83},
  journal   = {Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques},
  number    = {9},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {0034-6748},
  doi       = {10.1063/1.4754126},
  pages     = {3},
  year      = {2012},
  abstract  = {The combination of a non-coated silicon photodiode with electron repelling meshes makes a versatile detector for total fluorescence yield and electron yield techniques highly suitable for x-ray absorption spectroscopy. In particular, a copper mesh with a bias voltage allows to suppress or transmit the electron yield signal. The performance of this detection scheme has been characterized by near edge x-ray absorption fine structure studies of thermal oxidized silicon and sapphire. The results show that the new detector probes both electron yield and for a bias voltage exceeding the maximum photon energy the total fluorescence yield.},
  language  = {en}
}
@article{NorellEckertVanKuikenetal.2019,
  author    = {Norell, Jesper and Eckert, Sebastian and Van Kuiken, Benjamin E. and F{\"o}hlisch, Alexander and Odelius, Michael},
  title     = {Ab initio simulations of complementary K-edges and solvatization effects for detection of proton transfer in aqueous 2-thiopyridone},
  series = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr},
  volume    = {151},
  journal   = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr},
  number    = {11},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {0021-9606},
  doi       = {10.1063/1.5109840},
  pages     = {12},
  year      = {2019},
  abstract  = {The nitrogen and sulfur K-edge X-ray absorption spectra of aqueous 2-thiopyridone, a model system for excited-state proton transfer in several recent time-resolved measurements, have been simulated from ab initio molecular dynamics. Spectral signatures of the local intra- and inter-molecular structure are identified and rationalized, which facilitates experimental interpretation and optimization. In particular, comparison of aqueous and gas phase spectrum simulations assesses the previously unquantified solvatization effects, where hydrogen bonding is found to yield solvatochromatic shifts up to nearly 1 eV of the main peak positions. Thereby, while each K-edge can still decisively determine the local protonation of its core-excited site, only their combined, complementary fingerprints allow separating all of the three relevant molecular forms, giving a complete picture of the proton transfer.},
  language  = {en}
}
@article{SchickLeGuyaderPontiusetal.2016,
  author    = {Schick, Daniel and Le Guyader, Loic and Pontius, Niko and Radu, Ilie and Kachel, Torsten and Mitzner, Rolf and Zeschke, Thomas and Schuessler-Langeheine, Christian and F{\"o}hlisch, Alexander and Holldack, Karsten},
  title     = {Analysis of the halo background in femtosecond slicing experiments},
  series = {Journal of synchrotron radiation},
  volume    = {23},
  journal   = {Journal of synchrotron radiation},
  publisher = {International Union of Crystallography},
  address   = {Chester},
  issn      = {1600-5775},
  doi       = {10.1107/S160057751600401X},
  pages     = {700 -- 711},
  year      = {2016},
  abstract  = {The slicing facility FemtoSpeX at BESSY II offers unique opportunities to study photo-induced dynamics on femtosecond time scales by means of X-ray magnetic circular dichroism, resonant and non-resonant X-ray diffraction, and X-ray absorption spectroscopy experiments in the soft X-ray regime. Besides femtosecond X-ray pulses, slicing sources inherently also produce a so-called `halo' background with a different time structure, polarization and pointing. Here a detailed experimental characterization of the halo radiation is presented, and a method is demonstrated for its correct and unambiguous removal from femtosecond time-resolved data using a special laser triggering scheme as well as analytical models. Examples are given for time-resolved measurements with corresponding halo correction, and errors of the relevant physical quantities caused by either neglecting or by applying a simplified model to describe this background are estimated.},
  language  = {en}
}
@article{KunnusJosefssonRajkovicetal.2016,
  author    = {Kunnus, Kristjan and Josefsson, Ida and Rajkovic, Ivan and Schreck, Simon and Quevedo, Wilson and Beye, Martin and Gr{\"u}bel, Sebastian and Scholz, Mirko and Nordlund, Dennis and Zhang, Wenkai and Hartsock, Robert W. and Gaffney, Kelly J. and Schlotter, William F. and Turner, Joshua J. and Kennedy, Brian and Hennies, Franz and Techert, Simone and Wernet, Philippe and Odelius, Michael and F{\"o}hlisch, Alexander},
  title     = {Anti-Stokes resonant x-ray Raman scattering for atom specific and excited state selective dynamics},
  series = {NEW JOURNAL OF PHYSICS},
  volume    = {18},
  journal   = {NEW JOURNAL OF PHYSICS},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {1367-2630},
  doi       = {10.1088/1367-2630/18/10/103011},
  pages     = {9},
  year      = {2016},
  abstract  = {Ultrafast electronic and structural dynamics of matter govern rate and selectivity of chemical reactions, as well as phase transitions and efficient switching in functional materials. Since x-rays determine electronic and structural properties with elemental, chemical, orbital and magnetic selectivity, short pulse x-ray sources have become central enablers of ultrafast science. Despite of these strengths, ultrafast x-rays have been poor at picking up excited state moieties from the unexcited ones. With time-resolved anti-Stokes resonant x-ray Raman scattering (AS-RXRS) performed at the LCLS, and ab initio theory we establish background free excited state selectivity in addition to the elemental, chemical, orbital and magnetic selectivity of x-rays. This unparalleled selectivity extracts low concentration excited state species along the pathway of photo induced ligand exchange of Fe(CO)(5) in ethanol. Conceptually a full theoretical treatment of all accessible insights to excited state dynamics with AS-RXRS with transform-limited x-ray pulses is given-which will be covered experimentally by upcoming transform-limited x-ray sources.},
  language  = {en}
}
@article{JohanssonLeitnerBidermaneetal.2022,
  author    = {Johansson, Fredrik O. L. and Leitner, Torsten and Bidermane, Ieva and Born, Artur and F{\"o}hlisch, Alexander and Svensson, Svante and M{\aa}rtensson, Nils and Lindblad, Andreas},
  title     = {Auger- and photoelectron coincidences of molecular O2 adsorbed on Ag(111)},
  series = {Journal of electron spectroscopy and related phenomena : the international journal on theoretical and experimental aspects of electron spectroscopy},
  volume    = {256},
  journal   = {Journal of electron spectroscopy and related phenomena : the international journal on theoretical and experimental aspects of electron spectroscopy},
  publisher = {Elsevier},
  address   = {New York, NY [u.a.]},
  issn      = {0368-2048},
  doi       = {10.1016/j.elspec.2022.147174},
  pages     = {6},
  year      = {2022},
  abstract  = {The oxygen on Ag(111) system has been investigated with Auger electron-photoelectron coincidence spectroscopy (APECS). The coincidence spectra between O 1s core level photoelectrons and O KLL Auger electrons have been studied together with Ag(3)d/AgM4,5NN coincidences. We also describe the electron-electron coincidence spectrometer setup, CoESCA, consisting of two angle resolved time-of-flight spectrometers at a synchrotron light source. Contributions from molecular oxygen and chemisorbed oxygen are assigned using the coincidence data, conclusions are drawn primarily from the O 1s/O KLL data. The data acquisition and treatment procedure are also outlined. The chemisorbed oxygen species observed are relevant for the catalytic ethylene oxidation.},
  language  = {en}
}
@article{EckertVazdaCruzOchmannetal.2021,
  author    = {Eckert, Sebastian and Vaz da Cruz, Vin{\´i}cius and Ochmann, Miguel and Ahnen, Inga von and F{\"o}hlisch, Alexander and Huse, Nils},
  title     = {Breaking the symmetry of pyrimidine},
  series = {The journal of physical chemistry letters},
  volume    = {12},
  journal   = {The journal of physical chemistry letters},
  number    = {35},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1948-7185},
  doi       = {10.1021/acs.jpclett.1c01865},
  pages     = {8637 -- 8643},
  year      = {2021},
  abstract  = {Symmetry and its breaking crucially define the chemical properties of molecules and their functionality. Resonant inelastic X-ray scattering is a local electronic structure probe reporting on molecular symmetry and its dynamical breaking within the femtosecond scattering duration. Here, we study pyrimidine, a system from the C-2v point group, in an aqueous solution environment, using scattering though its 2a(2) resonance. Despite the absence of clean parity selection rules for decay transitions from in-plane orbitals, scattering channels including decay from the 7b(2) and 11a(1) orbitals with nitrogen lone pair character are a direct probe for molecular symmetry. Computed spectra of explicitly solvated molecules sampled from a molecular dynamics simulation are combined with the results of a quantum dynamical description of the X-ray scattering process. We observe dominant signatures of core-excited Jahn-Teller induced symmetry breaking for resonant excitation. Solvent contributions are separable by shortening of the effective scattering duration through excitation energy detuning.},
  language  = {en}
}
@article{KuehnSorgenfreiGiangrisostomietal.2018,
  author    = {K{\"u}hn, Danilo and Sorgenfrei, Nomi and Giangrisostomi, Erika and Jay, Raphael and Musazay, Abdurrahman and Ovsyannikov, Ruslan and Strahlman, Christian and Svensson, Svante and M{\aa}rtensson, Nils and F{\"o}hlisch, Alexander},
  title     = {Capabilities of angle resolved time of flight electron spectroscopy with the 60 degrees wide angle acceptance lens},
  series = {Journal of electron spectroscopy and related phenomena : the international journal on theoretical and experimental aspects of electron spectroscopy},
  volume    = {224},
  journal   = {Journal of electron spectroscopy and related phenomena : the international journal on theoretical and experimental aspects of electron spectroscopy},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0368-2048},
  doi       = {10.1016/j.elspec.2017.06.008},
  pages     = {45 -- 50},
  year      = {2018},
  abstract  = {The simultaneous detection of energy, momentum and temporal information in electron spectroscopy is the key aspect to enhance the detection efficiency in order to broaden the range of scientific applications. Employing a novel 60 degrees wide angle acceptance lens system, based on an additional accelerating electron optical element, leads to a significant enhancement in transmission over the previously employed 30 degrees electron lenses. Due to the performance gain, optimized capabilities for time resolved electron spectroscopy and other high transmission applications with pulsed ionizing radiation have been obtained. The energy resolution and transmission have been determined experimentally utilizing BESSY II as a photon source. Four different and complementary lens modes have been characterized. (C) 2017 The Authors. Published by Elsevier B.V.},
  language  = {en}
}
@misc{KuehnSorgenfreiGiangrisostomietal.2018,
  author    = {K{\"u}hn, Danilo and Sorgenfrei, Nomi and Giangrisostomi, Erika and Jay, Raphael Martin and Musazayb, Abdurrahman and Ovsyannikov, Ruslan and Str{\aa}hlman, Christian and Svensson, Svante and M{\aa}rtensson, Nils and F{\"o}hlisch, Alexander},
  title     = {Capabilities of angle resolved time of flight electron spectroscopy with the 60 degrees wide angle acceptance lens},
  series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  number    = {782},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-43662},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-436629},
  pages     = {45 -- 50},
  year      = {2018},
  abstract  = {The simultaneous detection of energy, momentum and temporal information in electron spectroscopy is the key aspect to enhance the detection efficiency in order to broaden the range of scientific applications. Employing a novel 60 degrees wide angle acceptance lens system, based on an additional accelerating electron optical element, leads to a significant enhancement in transmission over the previously employed 30 degrees electron lenses. Due to the performance gain, optimized capabilities for time resolved electron spectroscopy and other high transmission applications with pulsed ionizing radiation have been obtained. The energy resolution and transmission have been determined experimentally utilizing BESSY II as a photon source. Four different and complementary lens modes have been characterized. (C) 2017 The Authors. Published by Elsevier B.V.},
  language  = {en}
}
@article{YinInhesterVeeduetal.2017,
  author    = {Yin, Zhong and Inhester, Ludger and Veedu, Sreevidya Thekku and Quevedo, Wilson and Pietzsch, Annette and Wernet, Philippe and Groenhof, Gerrit and F{\"o}hlisch, Alexander and Grubmueller, Helmut and Techert, Simone},
  title     = {Cationic and Anionic Impact on the Electronic Structure of Liquid Water},
  series = {The journal of physical chemistry letters},
  volume    = {8},
  journal   = {The journal of physical chemistry letters},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1948-7185},
  doi       = {10.1021/acs.jpclett.7b01392},
  pages     = {3759 -- 3764},
  year      = {2017},
  abstract  = {Hydration shells around ions are crucial for many fundamental biological and chemical processes. Their local physicochemical properties are quite different from those of bulk water and hard to probe experimentally. We address this problem by combining soft X-ray spectroscopy using a liquid jet and molecular dynamics (MD) simulations together with ab initio electronic structure calculations to elucidate the water ion interaction in a MgCl2 solution at the molecular level. Our results reveal that salt ions mainly affect the electronic properties of water molecules in close vicinity and that the oxygen K-edge X-ray emission spectrum of water molecules in the first solvation shell differs significantly from that of bulk water. Ion-specific effects are identified by fingerprint features in the water X-ray emission spectra. While Mg2+ ions cause a bathochromic shift of the water lone pair orbital, the 3p orbital of the Cl- ions causes an additional peak in the water emission spectrum at around 528 eV.},
  language  = {en}
}
@article{BeyeOebergXinetal.2016,
  author    = {Beye, Martin and {\"O}berg, Henrik and Xin, Hongliang and Dakovski, Georgi L. and F{\"o}hlisch, Alexander and Gladh, Jorgen and Hantschmann, Markus and Hieke, Florian and Kaya, Sarp and K{\"u}hn, Danilo and LaRue, Jerry and Mercurio, Giuseppe and Minitti, Michael P. and Mitra, Ankush and Moeller, Stefan P. and Ng, May Ling and Nilsson, Anders and Nordlund, Dennis and Norskov, Jens and {\"O}str{\"o}m, Henrik and Ogasawara, Hirohito and Persson, Mats and Schlotter, William F. and Sellberg, Jonas A. and Wolf, Martin and Abild-Pedersen, Frank and Pettersson, Lars G. M. and Wurth, Wilfried},
  title     = {Chemical Bond Activation Observed with an X-ray Laser},
  series = {The journal of physical chemistry letters},
  volume    = {7},
  journal   = {The journal of physical chemistry letters},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1948-7185},
  doi       = {10.1021/acs.jpclett.6b01543},
  pages     = {3647 -- 3651},
  year      = {2016},
  abstract  = {The concept of bonding and antibonding orbitals is fundamental in chemistry. The population of those orbitals and the energetic difference between the two reflect the strength of the bonding interaction. Weakening the bond is expected to reduce this energetic splitting, but the transient character of bond-activation has so far prohibited direct experimental access. Here we apply time-resolved soft X-ray spectroscopy at a free electron laser to directly observe the decreased bonding antibonding splitting following bond-activation using an ultrashort optical laser pulse.},
  language  = {en}
}
@unpublished{FoehlischdeGrootOdeliusetal.2014,
  author    = {F{\"o}hlisch, Alexander and de Groot, F. M. F. and Odelius, Michael and Techert, Simone and Wernet, P.},
  title     = {Comment on "state-dependent electron delocalization dynamics at the solute-solvent interface: soft-x-ray absorption spectroscopy and lambda b initio calculations"},
  series = {Physical review letters},
  volume    = {112},
  journal   = {Physical review letters},
  number    = {12},
  publisher = {American Physical Society},
  address   = {College Park},
  issn      = {0031-9007},
  doi       = {10.1103/PhysRevLett.112.129302},
  pages     = {2},
  year      = {2014},
  language  = {en}
}
@article{WernetLeitnerJosefssonetal.2017,
  author    = {Wernet, Philippe and Leitner, T. and Josefsson, Ida and Mazza, T. and Miedema, P. S. and Schroder, H. and Beye, Martin and Kunnus, K. and Schreck, S. and Radcliffe, P. and Dusterer, S. and Meyer, M. and Odelius, Michael and Fohlisch, Alexander},
  title     = {Communication: Direct evidence for sequential dissociation of gas-phase Fe(CO)(5) via a singlet pathway upon excitation at 266 nm},
  series = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr},
  volume    = {146},
  journal   = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {0021-9606},
  doi       = {10.1063/1.4984774},
  pages     = {5},
  year      = {2017},
  abstract  = {We prove the hitherto hypothesized sequential dissociation of Fe(CO)(5) in the gas phase upon photoexcitation at 266 nm via a singlet pathway with time-resolved valence and core-level photoelectron spectroscopy with an x-ray free-electron laser. Valence photoelectron spectra are used to identify free CO molecules and to determine the time constants of stepwise dissociation to Fe(CO)(4) within the temporal resolution of the experiment and further to Fe(CO)(3) within 3 ps. Fe 3p core-level photoelectron spectra directly reflect the singlet spin state of the Fe center in Fe(CO)(5), Fe(CO)(4), and Fe(CO)(3) showing that the dissociation exclusively occurs along a singlet pathway without triplet-state contribution. Our results are important for assessing intra- and intermolecular relaxation processes in the photodissociation dynamics of the prototypical Fe(CO)(5) complex in the gas phase and in solution, and they establish time-resolved core-level photoelectron spectroscopy as a powerful tool for determining the multiplicity of transition metals in photochemical reactions of coordination complexes. Published by AIP Publishing.},
  language  = {en}
}
@article{NiskanenFondellSahleetal.2019,
  author    = {Niskanen, Johannes and Fondell, Mattis and Sahle, Christoph J. and Eckert, Sebastian and Jay, Raphael Martin and Gilmore, Keith and Pietzsch, Annette and Dantz, Marcus and Lu, Xingye and McNally, Daniel E. and Schmitt, Thorsten and Vaz da Cruz, Vinicius and Kimberg, Victor and F{\"o}hlisch, Alexander and Gel'mukhanov, Faris},
  title     = {Compatibility of quantitative X-ray spectroscopy with continuous distribution models of water at ambient conditions},
  series = {Proceedings of the National Academy of Sciences of the United States of America},
  volume    = {116},
  journal   = {Proceedings of the National Academy of Sciences of the United States of America},
  number    = {10},
  publisher = {National Acad. of Sciences},
  address   = {Washington},
  issn      = {0027-8424},
  doi       = {10.1073/pnas.1815701116},
  pages     = {4058 -- 4063},
  year      = {2019},
  abstract  = {The phase diagram of water harbors controversial views on underlying structural properties of its constituting molecular moieties, its fluctuating hydrogen-bonding network, as well as pair-correlation functions. In this work, long energy-range detection of the X-ray absorption allows us to unambiguously calibrate the spectra for water gas, liquid, and ice by the experimental atomic ionization cross-section. In liquid water, we extract the mean value of 1.74 +/- 2.1\% donated and accepted hydrogen bonds per molecule, pointing to a continuous-distribution model. In addition, resonant inelastic X-ray scattering with unprecedented energy resolution also supports continuous distribution of molecular neighborhoods within liquid water, as do X-ray emission spectra once the femtosecond scattering duration and proton dynamics in resonant X-ray-matter interaction are taken into account. Thus, X-ray spectra of liquid water in ambient conditions can be understood without a two-structure model, whereas the occurrence of nanoscale-length correlations within the continuous distribution remains open.},
  language  = {en}
}
@article{JayEckertVazdaCruzetal.2019,
  author    = {Jay, Raphael Martin and Eckert, Sebastian and Vaz da Cruz, Vinicius and Fondell, Mattis and Mitzner, Rolf and F{\"o}hlisch, Alexander},
  title     = {Covalency-driven preservation of local charge densities in a metal-to-ligand charge-transfer excited iron photosensitizer},
  series = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition},
  volume    = {58},
  journal   = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition},
  number    = {31},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1433-7851},
  doi       = {10.1002/anie.201904761},
  pages     = {10742 -- 10746},
  year      = {2019},
  abstract  = {Charge-density rearrangements after metal-to-ligand charge-transfer excitation in an iron photosensitizer are investigated by R. M Jay, A. Fohlisch et al. in their Communication (DOI: 10.1002/anie.201904761). By using time-resolved X-ray absorption spectroscopy, surprising covalency-effects are revealed that inhibit charge-separation at the intra-molecular level. Furthermore, the underlying mechanism is proposed to be generally in effect for all commonly used photosensitizers in light-harvesting applications, which challenges the common perception of electronic charge-transfer.},
  language  = {en}
}
@article{PietzschNiskanenVazdaCruzetal.2022,
  author    = {Pietzsch, Annette and Niskanen, Johannes and Vaz da Cruz, Vinicius and B{\"u}chner, Robby and Eckert, Sebastian and Fondell, Mattis and Jay, Raphael Martin and Lu, Xingye and McNally, Daniel and Schmitt, Thorsten and F{\"o}hlisch, Alexander},
  title     = {Cuts through the manifold of molecular H2O potential energy surfaces in liquid water at ambient conditions},
  series = {Proceedings of the National Academy of Sciences of the United States of America},
  volume    = {119},
  journal   = {Proceedings of the National Academy of Sciences of the United States of America},
  number    = {28},
  publisher = {National Acad. of Sciences},
  address   = {Washington, DC},
  issn      = {1091-6490},
  doi       = {10.1073/pnas.2118101119},
  pages     = {6},
  year      = {2022},
  abstract  = {The fluctuating hydrogen bridge bonded network of liquid water at ambient conditions entails a varied ensemble of the underlying constituting H2O molecular moieties. This is mirrored in a manifold of the H2O molecular potentials. Subnatural line width resonant inelastic X-ray scattering allowed us to quantify the manifold of molecular potential energy surfaces along the H2O symmetric normal mode and the local asymmetric O-H bond coordinate up to 1 and 1.5 angstrom, respectively. The comparison of the single H2O molecular potentials and spectroscopic signatures with the ambient conditions liquid phase H2O molecular potentials is done on various levels. In the gas phase, first principles, Morse potentials, and stepwise harmonic potential reconstruction have been employed and benchmarked. In the liquid phase the determination of the potential energy manifold along the local asymmetric O-H bond coordinate from resonant inelastic X-ray scattering via the bound state oxygen ls to 4a(1) resonance is treated within these frameworks. The potential energy surface manifold along the symmetric stretch from resonant inelastic X-ray scattering via the oxygen 1 s to 2b(2) resonance is based on stepwise harmonic reconstruction. We find in liquid water at ambient conditions H2O molecular potentials ranging from the weak interaction limit to strongly distorted potentials which are put into perspective to established parameters, i.e., intermolecular O-H, H-H, and O-O correlation lengths from neutron scattering.},
  language  = {en}
}