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  • 1.
    Ablyasova, Olesya S.
    et al.
    Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany;Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
    Guo, Meiyuan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. SSRL, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
    Zamudio-Bayer, Vicente
    Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
    Kubin, Markus
    Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
    Gitzinger, Tim
    Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany;Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
    da Silva Santos, Mayara
    Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany;Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
    Flach, Max
    Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany;Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
    Timm, Martin
    Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
    Lundberg, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Lau, J. Tobias
    Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany;Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
    Hirsch, Konstantin
    Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
    Electronic Structure of the Complete Series of Gas-Phase Manganese Acetylacetonates by X-ray Absorption Spectroscopy2023In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 127, no 34, p. 7121-7131Article in journal (Refereed)
    Abstract [en]

    Metal centers in transition metal–ligand complexes occur in a variety of oxidation states causing their redox activity and therefore making them relevant for applications in physics and chemistry. The electronic state of these complexes can be studied by X-ray absorption spectroscopy, which is, however, due to the complex spectral signature not always straightforward. Here, we study the electronic structure of gas-phase cationic manganese acetylacetonate complexes Mn(acac)1–3+ using X-ray absorption spectroscopy at the metal center and ligand constituents. The spectra are well reproduced by multiconfigurational wave function theory, time-dependent density functional theory as well as parameterized crystal field and charge transfer multiplet simulations. This enables us to get detailed insights into the electronic structure of ground-state Mn(acac)1–3+ and extract empirical parameters such as crystal field strength and exchange coupling from X-ray excitation at both the metal and ligand sites. By comparison to X-ray absorption spectra of neutral, solvated Mn(acac)2,3 complexes, we also show that the effect of coordination on the L3 excitation energy, routinely used to identify oxidation states, can contribute about 40–50% to the observed shift, which for the current study is 1.9 eV per oxidation state.

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  • 2.
    Couto, Rafael C.
    et al.
    Royal Inst Technol, Sch Chem Biotechnol & Hlth, Dept Theoret Chem & Biol, SE-10691 Stockholm, Sweden.;Stockholm Univ, Albanova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden..
    Hua, Weijie
    Nanjing Univ Sci & Technol, Sch Sci, Dept Appl Phys, MIIT Key Lab Semicond Microstruct & Quantum Sensi, Nanjing 210094, Peoples R China..
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Lund Univ, Dept Phys, Box 118, S-22100 Lund, Sweden.;Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindliche Rontgenspektroskopie, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Kjellsson, Ludvig
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. European XFEL GmbH, Holzkoppel 4, D-22869 Schenefeld, Germany..
    Sorensen, Stacey L.
    Lund Univ, Dept Phys, Box 118, S-22100 Lund, Sweden..
    Kubin, Markus
    Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindliche Rontgenspektroskopie, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Bülow, Christine
    Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindliche Rontgenspektroskopie, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Timm, Martin
    Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindliche Rontgenspektroskopie, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Zamudio-Bayer, Vicente
    Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindliche Rontgenspektroskopie, Albert Einstein Str 15, D-12489 Berlin, Germany..
    von Issendorff, Bernd
    Albert Ludwigs Univ Freiburg, Phys Inst, Hermann Herder Str 3, D-79104 Freiburg, Germany..
    Söderström, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Lau, J. Tobias
    Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindliche Rontgenspektroskopie, Albert Einstein Str 15, D-12489 Berlin, Germany.;Albert Ludwigs Univ Freiburg, Phys Inst, Hermann Herder Str 3, D-79104 Freiburg, Germany..
    Rubensson, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Ågren, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Tomsk State Univ, 36 Lenin Ave, Tomsk, Russia..
    Carravetta, Vincenzo
    CNR, IPCF, Via Moruzzi 1, I-56124 Pisa, Italy..
    Breaking inversion symmetry by protonation: experimental and theoretical NEXAFS study of the diazynium ion, N2H+2021In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 23, no 32, p. 17166-17176Article in journal (Refereed)
    Abstract [en]

    As an example of symmetry breaking in NEXAFS spectra of protonated species we present a high resolution NEXAFS spectrum of protonated dinitrogen, the diazynium ion N2H+. By ab initio calculations we show that the spectrum consists of a superposition of two nitrogen 1s absorption spectra, each including a pi* band, and a nitrogen 1s to H+ charge transfer band followed by a weak irregular progression of high energy excitations. Calculations also show that, as an effect of symmetry breaking by protonation, the pi* transitions are separated by 0.23 eV, only slightly exceeding the difference in the corresponding dark (symmetry forbidden) and bright (symmetry allowed) core excitations of neutral N-2. By DFT and calculations and vibrational analysis, the complex pi* excitation band of N2H+ is understood as due to the superposition of the significantly different vibrational progressions of excitations from terminal and central nitrogen atoms, both leading to bent final state geometries. We also show computationally that the electronic structure of the charge transfer excitation smoothly depends on the nitrogen-proton distance and that there is a clear extension of the spectra going from infinity to close nitrogen-proton distance where fine structures show some, although not fully detailed, similarities. An interesting feature of partial localization of the nitrogen core orbitals, with a strong, non-monotonous, variation with nitrogen-proton distance could be highlighted. Specific effects could be unraveled when comparing molecular cation NEXAFS spectra, as represented by recently recorded spectra of N-2(+) and CO+, and spectra of protonated molecules as represented here by the N2H+ ion. Both types containing rich physical effects not represented in NEXAFS of neutral molecules because of the positive charge, whereas protonation also breaks the symmetry. The effect of the protonation on dinitrogen can be separated in charge, which extends the high-energy part of the spectrum, and symmetry-breaking, which is most clearly seen in the low-energy pi* transition.

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  • 3.
    Delcey, Mickaël G.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Lund Univ, Dept Phys, Box 118, SE-22100 Lund, Sweden; Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindl Rontgenspektroskopie, Albert Einstein Str 15, D-12489 Berlin, Germany.
    Timm, Martin
    Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindl Rontgenspektroskopie, Albert Einstein Str 15, D-12489 Berlin, Germany.;Tech Univ Berlin, Inst Opt & Atomare Phys, Hardenbergstr 36, D-10623 Berlin, Germany..
    Bülow, Christine
    Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindl Rontgenspektroskopie, Albert Einstein Str 15, D-12489 Berlin, Germany.;Albert Ludwigs Univ Freiburg, Phys Inst, Hermann Herder Str 3, D-79104 Freiburg, Germany..
    Zamudio-Bayer, Vicente
    Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindl Rontgenspektroskopie, Albert Einstein Str 15, D-12489 Berlin, Germany..
    von Issendorff, Bernd
    Albert Ludwigs Univ Freiburg, Phys Inst, Hermann Herder Str 3, D-79104 Freiburg, Germany..
    Lau, J. Tobias
    Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindl Rontgenspektroskopie, Albert Einstein Str 15, D-12489 Berlin, Germany.;Albert Ludwigs Univ Freiburg, Phys Inst, Hermann Herder Str 3, D-79104 Freiburg, Germany..
    Lundberg, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Soft X-ray signatures of cationic manganese-oxo systems, including a high-spin manganese(v) complex2022In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 24, no 6, p. 3598-3610Article in journal (Refereed)
    Abstract [en]

    Manganese–oxo species catalyze key reactions, including C–H bond activation or dioxygen formation in natural photosynthesis. To better understand relevant reaction intermediates, we characterize electronic states and geometric structures of [MnOn]+ manganese–oxo complexes that represent a wide range of manganese oxidation states. To this end, we apply soft X-ray spectroscopy in a cryogenic ion trap, combined with multiconfigurational wavefunction calculations. We identify [MnO2]+ as a rare high-spin manganese(V) oxo complex with key similarities to six-coordinated manganese(V) oxo systems that are proposed as reaction intermediates in catalytic dioxygen bond formation.

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  • 4.
    Leroux, Juliette
    et al.
    Univ Caen Normandie, CIMAP, CEA, CNRS,ENSICAEN, F-14050 Caen, France.;Deutsch Elektronen Synchrotron DESY, Hamburg, Germany..
    Kotobi, Amir
    Deutsch Elektronen Synchrotron DESY, Hamburg, Germany.;Helmholtz Zentrum Hereon, Inst Surface Sci, D-21502 Geesthacht, Germany..
    Hirsch, Konstantin
    Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindliche Rontgenspekt, D-12489 Berlin, Germany..
    Lau, Tobias
    Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindliche Rontgenspekt, D-12489 Berlin, Germany..
    Ortiz-Mahecha, Carlos
    Hamburg Univ Technol, Inst Polymers & Composites, D-21073 Hamburg, Germany..
    Maksimov, Dmitrii
    Max Planck Inst Struct & Dynam Matter, D-22761 Hamburg, Germany..
    Meissner, Robert
    Helmholtz Zentrum Hereon, Inst Surface Sci, D-21502 Geesthacht, Germany.;Hamburg Univ Technol, Inst Polymers & Composites, D-21073 Hamburg, Germany..
    Oostenrijk, Bart
    Hamburg Ctr Ultrafast Imaging, Hamburg, Germany..
    Rossi, Mariana
    Max Planck Inst Struct & Dynam Matter, D-22761 Hamburg, Germany..
    Schubert, Kaja
    Deutsch Elektronen Synchrotron DESY, Hamburg, Germany..
    Timm, Martin
    Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindliche Rontgenspekt, D-12489 Berlin, Germany..
    Trinter, Florian
    Goethe Univ Frankfurt Main, Inst Kernphys, D-60438 Frankfurt, Germany.;Max Planck Gesell, Fritz Haber Inst, Mol Phys, D-14195 Berlin, Germany..
    Unger, Isaak
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Zamudio-Bayer, Vicente
    Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindliche Rontgenspekt, D-12489 Berlin, Germany..
    Schwob, Lucas
    Deutsch Elektronen Synchrotron DESY, Hamburg, Germany..
    Bari, Sadia
    Deutsch Elektronen Synchrotron DESY, Hamburg, Germany.;Hamburg Ctr Ultrafast Imaging, Hamburg, Germany.;Univ Groningen, Zernike Inst Adv Mat, NL-9747 AG Groningen, Netherlands..
    Mapping the electronic transitions of protonation sites in peptides using soft X-ray action spectroscopy2023In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 25, no 37, p. 25603-25618Article in journal (Refereed)
    Abstract [en]

    Near-edge X-ray absorption mass spectrometry (NEXAMS) around the nitrogen and oxygen K-edges was employed on gas-phase peptides to probe the electronic transitions related to their protonation sites, namely at basic side chains, the N-terminus and the amide oxygen. The experimental results are supported by replica exchange molecular dynamics and density-functional theory and restricted open-shell configuration with single calculations to attribute the transitions responsible for the experimentally observed resonances. We studied five tailor-made glycine-based pentapeptides, where we identified the signature of the protonation site of N-terminal proline, histidine, lysine and arginine, at 406 eV, corresponding to N 1s & RARR; & sigma;*(NHx+) (x = 2 or 3) transitions, depending on the peptides. We compared the spectra of pentaglycine and triglycine to evaluate the sensitivity of NEXAMS to protomers. Separate resonances have been identified to distinguish two protomers in triglycine, the protonation site at the N-terminus at 406 eV and the protonation site at the amide oxygen characterized by a transition at 403.1 eV.

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  • 5.
    Lindblad, Rebecka
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Lund Univ, Dept Phys, Box 118, S-22100 Lund, Sweden.;Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindl Rontgenspektroskopie, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Kjellsson, Ludvig
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics. European XFEL GmbH, Holzkoppel 4, 22869 Schenefeld, Germany..
    De Santis, Emiliano
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Zamudio-Bayer, Vicente
    von Issendorff, Bernd
    Sorensen, Stacey L.
    Lau, J. Tobias
    Hua, Weijie
    Carravetta, Vincenzo
    Rubensson, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Ågren, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Couto, Rafael Carvalho
    Experimental and theoretical near-edge x-ray-absorption fine-structure studies of NO+2022In: Physical Review A: covering atomic, molecular, and optical physics and quantum information, ISSN 2469-9926, E-ISSN 2469-9934, Vol. 106, no 4, article id 042814Article in journal (Refereed)
    Abstract [en]

    Experimental near-edge x-ray-absorption fine-structure (NEXAFS) spectra of the nitrosonium NO+ ion are presented and theoretically analyzed. While neutral NO has an open shell, the cation is a closed-shell species, which for NEXAFS leads to the simplicity of a closed-shell spectrum. Compared to neutral NO, the electrons in the cation experience a stronger Coulomb potential, which introduces a shift of the ionization potential towards higher energies, a depletion of intensity in a large interval above the pi* resonance, and a shift of the sigma* resonance from the continuum to below the ionization threshold. NEXAFS features at the nitrogen and oxygen K edges of NO+ are compared, as well as NEXAFS features at the nitrogen edges of the isoelectronic closed-shell species NO+, N2, and N2H+.

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  • 6.
    Svensson, Pamela
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Schwob, Lucas
    Deutsch Elektronen Synchrotron DESY, Notke str 85, D-22607 Hamburg, Germany..
    Grånäs, Oscar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Unger, Isaak
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Timneanu, Nicusor
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Vieli, Anna-Lydia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Zamudio-Bayer, Vicente
    Helmholtz Zent Berlin Materialien & Energie, Abt Hochempfindl Rontgenspektroskopie, D-12489 Berlin, Germany..
    Timm, Martin
    Helmholtz Zent Berlin Materialien & Energie, Abt Hochempfindl Rontgenspektroskopie, D-12489 Berlin, Germany..
    Hirsch, Konstantin
    Helmholtz Zent Berlin Materialien & Energie, Abt Hochempfindl Rontgenspektroskopie, D-12489 Berlin, Germany..
    Caleman, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics. DESY, Ctr Free Electron Laser Sci, D-22607 Hamburg, Germany..
    Berholts, Marta
    Univ Tartu, Inst Phys, W Ostwald 1, EE-50411 Tartu, Estonia..
    Heavy element incorporation in nitroimidazole radiosensitizers: molecular-level insights into fragmentation dynamics2024In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 26, no 2, p. 770-779Article in journal (Refereed)
    Abstract [en]

    The present study investigates the photofragmentation behavior of iodine-enhanced nitroimidazole-based radiosensitizer model compounds in their protonated form using near-edge X-ray absorption mass spectrometry and quantum mechanical calculations. These molecules possess dual functionality: improved photoabsorption capabilities and the ability to generate species that are relevant to cancer sensitization upon photofragmentation. Four samples were investigated by scanning the generated fragments in the energy regions around C 1s, N 1s, O 1s, and I 3d-edges with a particular focus on NO2+ production. The experimental summed ion yield spectra are explained using the theoretical near-edge X-ray absorption fine structure spectrum based on density functional theory. Born-Oppenheimer-based molecular dynamics simulations were performed to investigate the fragmentation processes.

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