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1. Structural pathways for ultrafast melting of optically excited thin polycrystalline Palladium films

Author

Antonowicz, Jerzy, Olczak, Adam, Sokolowski-Tinten, Klaus, Zalden, Peter, Milov, Igor, Dzięgielewski, Przemysław, Bressler, Christian, Chapman, Henry N., Chojnacki, Michał, Dłużewski, Piotr, Rodriguez-Fernandez, Angel, Fronc, Krzysztof, Gawełda, Wojciech, Georgarakis, Konstantinos, Greer, Alan L., Jacyna, Iwanna, van de Kruijs, Robbert W. E., Kamiński, Radosław, Khakhulin, Dmitry, Klinger, Dorota, Kosyl, Katarzyna M., Kubicek, Katharina, Migdal, Kirill P., Minikayev, Roman, Panagiotopoulos, Nikolaos T., Sikora, Marcin, Sun, Peihao, Yousef, Hazem, Zajkowska, Wiktoria, Zhakhovski, Vasily V., and Sobierajski, Ryszard

Subjects
Condensed Matter - Materials Science
Abstract

Due to its extremely short timescale, the non-equilibrium melting of metals is exceptionally difficult to probe experimentally. The knowledge of melting mechanisms is thus based mainly on the results of theoretical predictions. This work reports on the investigation of ultrafast melting of thin polycrystalline Pd films studied by optical laser pump - X-ray free-electron laser probe experiments and molecular-dynamics simulations. By acquiring X-ray diffraction snapshots with sub-picosecond resolution, we capture the sample's atomic structure during its transition from the crystalline to the liquid state. Bridging the timescales of experiments and simulations allows us to formulate a realistic microscopic picture of melting. We demonstrate that the existing models of strongly non-equilibrium melting, developed for systems with relatively weak electron-phonon coupling, remain valid even for ultrafast heating rates achieved in femtosecond laser-excited Pd. Furthermore, we highlight the role of pre-existing and transiently generated crystal defects in the transition to the liquid state., Comment: main manuscript 33 pages, 9 figures; supplemental material 19 pages, 13 figures - all in one file

Published
2023

3. Structural pathways for ultrafast melting of optically excited thin polycrystalline Palladium films

Author

Antonowicz, Jerzy, Olczak, Adam, Sokolowski-Tinten, Klaus, Zalden, Peter, Milov, Igor, Dzięgielewski, Przemysław, Bressler, Christian, Chapman, Henry N., Chojnacki, Michał, Dłużewski, Piotr, Rodriguez-Fernandez, Angel, Fronc, Krzysztof, Gawełda, Wojciech, Georgarakis, Konstantinos, Greer, Alan L., Jacyna, Iwanna, van de Kruijs, Robbert W.E., Kamiński, Radosław, Khakhulin, Dmitry, Klinger, Dorota, Kosyl, Katarzyna M., Kubicek, Katharina, Migdal, Kirill P., Minikayev, Roman, Panagiotopoulos, Nikolaos T., Sikora, Marcin, Sun, Peihao, Yousef, Hazem, Zajkowska-Pietrzak, Wiktoria, Zhakhovsky, Vasily V., and Sobierajski, Ryszard

Published
2024
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4. Spectroscopic Signatures of the Dynamical Hydrophobic Solvation Shell Formation

Author

Kirchberg, Henning, Nalbach, Peter, Bressler, Christian, and Thorwart, Michael

Subjects
Condensed Matter - Soft Condensed Matter
Abstract

When a hydrophilic solute in water is suddenly turned into a hydrophobic species, for instance, by photoionization, a layer of hydrated water molecules forms around the solute on a time scale of a few picoseconds. We study the dynamic build-up of the hydration shell around a hydrophobic solute on the basis of a time-dependent dielectric continuum model. Information about the solvent is spectroscopically extracted from the relaxation dynamics of a test dipole inside a static Onsager sphere in the nonequilibrium solvent. The growth process is described phenomenologically within two approaches. First, we consider a time-dependent thickness of the hydration layer which grows from zero to a finite value over a finite time. Second, we assume a time-dependent complex permittivity within a finite layer region around the Onsager sphere. The layer is modeled as a continuous dielectric with a much slower fluctuation dynamics. We find a time-dependent frequency shift down to the blue of the resonant absorption of the dipole, together with a dynamically decreasing line width, as compared to bulk water. The blue shift reflects the work performed against the hydrogen bonded network of the bulk solvent and is a directly measurable quantity. Our results are in agreement with an experiment on the hydrophobic solvation of iodine in water.

Published
2022
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6. A self-referenced in-situ arrival time monitor for X-ray free-electron lasers

Author

Diez, Michael, Galler, Andreas, Schulz, Sebastian, Boemer, Christina, Coffee, Ryan N., Hartmann, Nick, Heider, Rupert, Wagner, Martin S., Helml, Wolfram, Katayama, Tetsuo, Sato, Tokushi, Sato, Takahiro, Yabashi, Makina, and Bressler, Christian

Subjects
Physics - Optics, Physics - Instrumentation and Detectors
Abstract

We present a novel, highly versatile, and self-referenced arrival time monitor for measuring the femtosecond time delay between a hard X-ray pulse from a free-electron laser and an optical laser pulse, measured directly on the same sample used for pump-probe experiments. Two chirped and picosecond long optical supercontinuum pulses traverse the sample with a mutually fixed time delay of 970 fs, while a femtosecond X-ray pulse arrives at an instant in between both pulses. Behind the sample the supercontinuum pulses are temporally overlapped to yield near-perfect destructive interference in the absence of the X-ray pulse. Stimulation of the sample with an X-ray pulse delivers non-zero contributions at certain optical wavelengths, which serve as a measure of the relative arrival time of the X-ray pulse with an accuracy of better than 25 fs. We find an excellent agreement of our monitor with the existing timing diagnostics at the SACLA XFEL with a Pearson correlation value of 0.98. We demonstrate a high sensitivity to measure X-ray pulses with pulse energies as low as 30 $\mu$J. Using a free-flowing liquid jet as interaction sample ensures the full replacement of the sample volume for each X-ray/optical event, thus enabling its utility even at MHz repetition rate XFEL sources.

Published
2020
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7. Doming and spin cascade in Ferric Haems: Femtosecond X-ray Absorption and X-ray Emission Studies

Author

Bacellar, Camila, Kinschel, Dominik, Mancini, Giulia F., Ingle, Rebecca A., Rouxel, Jérémy, Cannelli, Oliviero, Cirelli, Claudio, Knopp, Gregor, Szlachetko, Jakub, Lima, Frederico A., Menzi, Samuel, Pamfilidis, Georgios, Kubicek, Katharina, Khakhulin, Dmitry, Gawelda, Wojciech, Rodriguez-Fernandez, Angel, Biednov, Mykola, Bressler, Christian, Arrell, Christopher A., Johnson, Philip J. M., Milne, Christopher, and Chergui, Majed

Subjects
Physics - Chemical Physics
Abstract

The structure-function relationship is at the heart of biology and major protein deformations are correlated to specific functions. In the case of heme proteins, doming is associated with the respiratory function in hemoglobin and myoglobin, while ruffling has been correlated with electron transfer processes, such as in the case of Cytochrome c (Cyt c). The latter has indeed evolved to become an important electron transfer protein in humans. In its ferrous form, it undergoes ligand release and doming upon photoexcitation, but its ferric form does not release the distal ligand, while the return to the ground state has been attributed to thermal relaxation. Here, by combining femtosecond Fe K-edge X-ray absorption near-edge structure (XANES) studies and femtosecond Fe Kalpha and Kbeta X-ray emission spectroscopy (XES), we demonstrate that the photocycle of ferric Cyt c is entirely due to a cascade among excited spin states of the Iron ion, causing the ferric heme to undergo doming, which we identify for the first time. We also argue that this pattern is common to all ferric haems, raising the question of the biological relevance of doming in such proteins.

Published
2020

8. Femtosecond X-ray emission study of the spin cross-over dynamics in haem proteins

Author

Kinschel, Dominik, Bacellar, Camila, Cannelli, Oliviero, Sorokin, Boris, Katayama, Tetsuo, Mancini, Giulia F., Rouxel, Jeremy R., Obara, Yuki, Nishitani, Junichi, Ito, Hironori, Ito, Terumasa, Kurahashi, Naoya, Higashimura, Chika, Kudo, Shotaro, Keane, Theo, Lima, Frederico A., Gawelda, Wojciech, Zalden, Peter, Schulz, Sebastian, Budarz, James, Khakhulin, Dmitry, Galler, Andreas, Bressler, Christian, Milne, Christopher J., Penfold, Thomas, Yabashi, Makina, Suzuki, Toshinori, Misawa, Kazuhiko, and Chergui, Majed

Subjects
Physics - Chemical Physics, Condensed Matter - Soft Condensed Matter, Physics - Biological Physics
Abstract

In haemoglobin (consisting of four globular myoglobin-like subunits), the change from the low-spin (LS) hexacoordinated haem to the high spin (HS) pentacoordinated domed form upon ligand detachment and the reverse process upon ligand binding, represent the transition states that ultimately drive the respiratory function. Visible-ultraviolet light has long been used to mimic the ligand release from the haem by photodissociation, while its recombination was monitored using time-resolved infrared to ultraviolet spectroscopic tools. However, these are neither element- nor spin-sensitive. Here we investigate the transition state in the case of Myoglobin-NO (MbNO) using femtosecond Fe Kalpha and Kbeta non-resonant X-ray emission spectroscopy (XES) at an X-ray free-electron laser upon photolysis of the Fe-NO bond. We find that the photoinduced change from the LS (S = 1/2) MbNO to the HS (S = 2) deoxy-myoglobin (deoxyMb) haem occurs in ca. 800 fs, and that it proceeds via an intermediate (S = 1) spin state. The XES observables also show that upon NO recombination to deoxyMb, the return to the planar MbNO ground state is an electronic relaxation from HS to LS taking place in ca. 30 ps. Thus, the entire ligand dissociation-recombination cycle in MbNO is a spin cross-over followed by a reverse spin cross-over process.

Published
2020
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9. X-ray parametric down-conversion: Challenging previous findings on the basis of improved experimental methods

Author

Boemer, Christina, Krebs, Dietrich, Diez, Michael, Rohringer, Nina, Galler, Andreas, and Bressler, Christian

Subjects
Physics - Optics
Abstract

X-ray parametric down-conversion is a fundamental nonlinear effect that promises a wide range of possible applications. Nevertheless, it has been scarcely investigated and unequivocal evidence of the effect is still missing for certain spectral regions. In particular, this is the case for down-conversion into pairs of x-ray and optical photons, which would open pathways to characterise and image valence electron-density fluctuations. In this work, we present a systematic approach to scan the parameter space, wherein we expect to identify the effect based on its characteristic signature. Within the resolution of the experimental setup we cannot establish any evidence for the nonlinear effect. Instead, we trace the measured signals back to elastic scattering contributions, thereby challenging the interpretation of previous studies on the effect of x-ray parametric down conversion producing photons in the visible spectral range. As a benchmark for future investigations of x-ray parametric down-conversion - both experimental and theoretical - we extract an upper bound for the effect's conversion efficiency of $10^{-11}$ within the resolution of our setup.

Published
2020

10. Site-selective and real-time observation of bimolecular electron transfer during photocatalytic water splitting

Author

Britz, Alexander, Bokarev, Sergey I., Assefa, Tadesse A., Bajnóczi, Éva G., Németh, Zoltán, Vankó, György, Rockstroh, Nils, Junge, Henrik, Beller, Matthias, Doumy, Gilles, March, Anne Marie, Southworth, Stephen H., Lochbrunner, Stefan, Kühn, Oliver, Bressler, Christian, and Gawelda, Wojciech

Subjects
Physics - Chemical Physics
Abstract

Time-resolved X-ray absorption spectroscopy has been utilized to monitor the bimolecular electron transfer in a photocatalytic water splitting system for the first time. This has been possible by uniting the local probe and element specific character of X-ray transitions with insights from high-level ab initio calculations. The specific target has been a heteroleptic [Ir$^{\rm III}$(ppy)$_2$(bpy)]$^+$ photosensitizer, in combination with triethylamine as a sacrificial reductant and Fe$_3$(CO)$_{12}$ as a water reduction catalyst. The relevant molecular transitions have been characterized via high-resolution Ir L-edge X-ray absorption spectroscopy on the picosecond time scale. The present findings enhance our understanding of functionally relevant bimolecular electron transfer reactions and thus will pave the road to rational optimization of photocatalytic performance., Comment: revised version

Published
2019

11. Ultrafast Two‐Color X‐Ray Emission Spectroscopy Reveals Excited State Landscape in a Base Metal Dyad.

Author

Nowakowski, Michal, Huber‐Gedert, Marina, Elgabarty, Hossam, Kalinko, Aleksandr, Kubicki, Jacek, Kertmen, Ahmet, Lindner, Natalia, Khakhulin, Dmitry, Lima, Frederico A., Choi, Tae‐Kyu, Biednov, Mykola, Schmitz, Lennart, Piergies, Natalia, Zalden, Peter, Kubicek, Katharina, Rodriguez‐Fernandez, Angel, Salem, Mohammad Alaraby, Canton, Sophie E., Bressler, Christian, and Kühne, Thomas D.

Subjects
CHARGE exchange, EMISSION spectroscopy, OPTICAL spectroscopy, EXCITED states, STRUCTURAL dynamics, CHARGE transfer, PROTON transfer reactions
Abstract

Effective photoinduced charge transfer makes molecular bimetallic assemblies attractive for applications as active light‐induced proton reduction systems. Developing competitive base metal dyads is mandatory for a more sustainable future. However, the electron transfer mechanisms from the photosensitizer to the proton reduction catalyst in base metal dyads remain so far unexplored. A Fe─Co dyad that exhibits photocatalytic H2 production activity is studied using femtosecond X‐ray emission spectroscopy, complemented by ultrafast optical spectroscopy and theoretical time‐dependent DFT calculations, to understand the electronic and structural dynamics after photoexcitation and during the subsequent charge transfer process from the FeII photosensitizer to the cobaloxime catalyst. This novel approach enables the simultaneous measurement of the transient X‐ray emission at the iron and cobalt K‐edges in a two‐color experiment. With this methodology, the excited state dynamics are correlated to the electron transfer processes, and evidence of the Fe→Co electron transfer as an initial step of proton reduction activity is unraveled. [ABSTRACT FROM AUTHOR]

Published
2024
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12. Nonadiabatic Charge Transfer within Photoexcited Nickel Porphyrins

Author

Naumova, Maria A., primary, Paveliuc, Gheorghe, additional, Biednov, Mykola, additional, Kubicek, Katharina, additional, Kalinko, Aleksandr, additional, Meng, Jie, additional, Liang, Mingli, additional, Rahaman, Ahibur, additional, Abdellah, Mohamed, additional, Checchia, Stefano, additional, Alves Lima, Frederico, additional, Zalden, Peter, additional, Gawelda, Wojciech, additional, Bressler, Christian, additional, Geng, Huifang, additional, Lin, Weihua, additional, Liu, Yan, additional, Zhao, Qian, additional, Pan, Qinying, additional, Akter, Marufa, additional, Kong, Qingyu, additional, Retegan, Marius, additional, Gosztola, David J., additional, Pápai, Mátyás, additional, Khakhulin, Dmitry, additional, Lawson Daku, Max, additional, Zheng, Kaibo, additional, and Canton, Sophie E., additional

Published
2024
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13. Spin cascade and doming in ferric hemes : Femtosecond X-ray absorption and X-ray emission studies

Author

Bacellar, Camila, Kinschel, Dominik, Mancini, Giulia F., Ingle, Rebecca A., Rouxel, Jérémy, Cannelli, Oliviero, Cirelli, Claudio, Knopp, Gregor, Szlachetko, Jakub, Lima, Frederico A., Menzi, Samuel, Pamfilidis, Georgios, Kubicek, Katharina, Khakhulin, Dmitry, Gawelda, Wojciech, Rodriguez-Fernandez, Angel, Biednov, Mykola, Bressler, Christian, Arrell, Christopher A., Johnson, Philip J. M., Milne, Christopher J., and Chergui, Majed

Published
2020

14. Femtosecond X-Ray Scattering Study of Ultrafast Photoinduced Structural Dynamics in Solvated [Co(terpy)2]2+

Author

Biasin, Elisa, van Driel, Tim Brandt, Kjær, Kasper S., Dohn, Asmus O., Christensen, Morten, Harlang, Tobias, Chabera, Pavel, Liu, Yizhu, Uhlig, Jens, Pápai, Mátyás, Németh, Zoltán, Hartsock, Robert, Liang, Winnie, Zhang, Jianxin, Alonso-Mori, Roberto, Chollet, Matthieu, Glownia, James M., Nelson, Silke, Sokaras, Dimosthenis, Assefa, Tadesse A., Britz, Alexander, Galler, Andreas, Gawelda, Wojciech, Bressler, Christian, Gaffney, Kelly J., Lemke, Henrik T., Møller, Klaus B., Nielsen, Martin M., Sundström, Villy, Vankó, György, Wärnmark, Kenneth, Canton, Sophie E., and Haldrup, Kristoffer

Subjects
Physics - Chemical Physics
Abstract

We study the structural dynamics of photoexcited [Co(terpy)2]2+ in an aqueous solution with ultrafast x-ray diffuse scattering experiments conducted at the Linac Coherent Light Source. Through direct comparisons with density functional theory calculations, our analysis shows that the photoexcitation event leads to elongation of the Co-N bonds, followed by coherent Co-N bond length oscillations arising from the impulsive excitation of a vibrational mode dominated by the symmetrical stretch of all six Co-N bonds. This mode has a period of 0.33 ps and decays on a subpicosecond time scale. We find that the equilibrium bond-elongated structure of the high spin state is established on a single-picosecond time scale and that this state has a lifetime of ~ 7 ps.

Published
2016
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15. Nonadiabatic Charge Transfer within Photoexcited Nickel Porphyrins

Author

Naumova, Maria A., Paveliuc, Gheorghe, Biednov, Mykola, Kubicek, Katharina, Kalinko, Aleksandr, Meng, Jie, Liang, Mingli, Rahaman, Ahibur, Abdellah, Mohamed, Checchia, Stefano, Alves Lima, Frederico, Zalden, Peter, Gawelda, Wojciech, Bressler, Christian, Geng, Huifang, Lin, Weihua, Liu, Yan, Zhao, Qian, Pan, Qinying, Akter, Marufa, Kong, Qingyu, Retegan, Marius, Gosztola, David J., Pápai, Mátyás, Khakhulin, Dmitry, Lawson Daku, Max, Zheng, Kaibo, Canton, Sophie E., Naumova, Maria A., Paveliuc, Gheorghe, Biednov, Mykola, Kubicek, Katharina, Kalinko, Aleksandr, Meng, Jie, Liang, Mingli, Rahaman, Ahibur, Abdellah, Mohamed, Checchia, Stefano, Alves Lima, Frederico, Zalden, Peter, Gawelda, Wojciech, Bressler, Christian, Geng, Huifang, Lin, Weihua, Liu, Yan, Zhao, Qian, Pan, Qinying, Akter, Marufa, Kong, Qingyu, Retegan, Marius, Gosztola, David J., Pápai, Mátyás, Khakhulin, Dmitry, Lawson Daku, Max, Zheng, Kaibo, and Canton, Sophie E.

Abstract

Metalloporphyrins with open d-shell ions can drive biochemical energy cycles. However, their utilization in photoconversion is hampered by rapid deactivation. Mapping the relaxation pathways is essential for elaborating strategies that can favorably alter the charge dynamics through chemical design and photoexcitation conditions. Here, we combine transient optical absorption spectroscopy and transient X-ray emission spectroscopy with femtosecond resolution to probe directly the coupled electronic and spin dynamics within a photoexcited nickel porphyrin in solution. Measurements and calculations reveal that a state with charge-transfer character mediates the formation of the thermalized excited state, thereby advancing the description of the photocycle for this important representative molecule. More generally, establishing that intramolecular charge-transfer steps play a role in the photoinduced dynamics of metalloporphyrins with open d-shell sets a conceptual ground for their development as building blocks capable of boosting nonadiabatic photoconversion in functional architectures through “hot” charge transfer down to the attosecond time scale.

Published
2024

19. Publisher’s Note: “Tracking structural solvent reorganization and recombination dynamics following e− photoabstraction from aqueous I− with femtosecond x-ray spectroscopy and scattering” [J. Chem. Phys. 157, 224201 (2022)]

Author

Vester, Peter, primary, Kubicek, Katharina, additional, Alonso-Mori, Roberto, additional, Assefa, Tadesse, additional, Biasin, Elisa, additional, Christensen, Morten, additional, Dohn, Asmus O., additional, van Driel, Tim B., additional, Galler, Andreas, additional, Gawelda, Wojciech, additional, Harlang, Tobias C. B., additional, Henriksen, Niels E., additional, Kjær, Kasper S., additional, Kuhlman, Thomas S., additional, Németh, Zoltán, additional, Nurekeyev, Zhangatay, additional, Pápai, Mátyás, additional, Rittman, Jochen, additional, Vankó, György, additional, Yavas, Hasan, additional, Zederkof, Diana B., additional, Bergmann, Uwe, additional, Nielsen, Martin M., additional, Møller, Klaus B., additional, Haldrup, Kristoffer, additional, and Bressler, Christian, additional

Published
2023
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20. Ultrafast Energy Transfer from Photoexcited Tryptophan to the Haem in Cytochrome c

Author

Bacellar, Camila, primary, Rouxel, Jérémy R., additional, Ingle, Rebecca A., additional, Mancini, Giulia F., additional, Kinschel, Dominik, additional, Cannelli, Oliviero, additional, Zhao, Yang, additional, Cirelli, Claudio, additional, Knopp, Gregor, additional, Szlachetko, Jakub, additional, Lima, Frederico A., additional, Menzi, Samuel, additional, Ozerov, Dmitry, additional, Pamfilidis, Georgios, additional, Kubicek, Katharina, additional, Khakhulin, Dmitry, additional, Gawelda, Wojciech, additional, Rodriguez-Fernandez, Angel, additional, Biednov, Mykola, additional, Bressler, Christian, additional, Arrell, Christopher A., additional, Johnson, Philip J. M., additional, Milne, Christopher J., additional, and Chergui, Majed, additional

Published
2023
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21. Tracking multiple components of a nuclear wavepacket in photoexcited Cu(I)-phenanthroline complex using ultrafast X-ray spectroscopy

Author

Katayama, Tetsuo, Northey, Thomas, Gawelda, Wojciech, Milne, Christopher J., Vankó, György, Lima, Frederico A., Bohinc, Rok, Németh, Zoltán, Nozawa, Shunsuke, Sato, Tokushi, Khakhulin, Dmitry, Szlachetko, Jakub, Togashi, Tadashi, Owada, Shigeki, Adachi, Shin-ichi, Bressler, Christian, Yabashi, Makina, and Penfold, Thomas J.

Published
2019
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23. Tracking structural solvent reorganization and recombination dynamics following e− photoabstraction from aqueous I− with femtosecond x-ray spectroscopy and scattering

Author

Vester, Peter, primary, Kubicek, Katharina, additional, Alonso-Mori, Roberto, additional, Assefa, Tadesse, additional, Biasin, Elisa, additional, Christensen, Morten, additional, Dohn, Asmus O., additional, van Driel, Tim B., additional, Galler, Andreas, additional, Gawelda, Wojciech, additional, Harlang, Tobias C. B., additional, Henriksen, Niels E., additional, Kjær, Kasper S., additional, Kuhlman, Thomas S., additional, Németh, Zoltán, additional, Nurekeyev, Zhangatay, additional, Pápai, Mátyás, additional, Rittman, Jochen, additional, Vankó, György, additional, Yavas, Hasan, additional, Zederkof, Diana B., additional, Bergmann, Uwe, additional, Nielsen, Martin M., additional, Møller, Klaus B., additional, Haldrup, Kristoffer, additional, and Bressler, Christian, additional

Published
2022
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25. A sensitive high repetition rate arrival time monitor for X-ray Free Electron Lasers

Author

Diez, Michael, primary, Kirchberg, Henning, additional, Galler, Andreas, additional, Schulz, Sebastian, additional, Bömer, Christina, additional, Biednov, Mykola, additional, Choi, Tae-Kyu, additional, Rodriguez-Fernandez, Angel, additional, Gawelda, Wojciech, additional, Khakhulin, Dmitri, additional, Kubicek, Katharina, additional, Lima, Frederico, additional, Otte, Florian, additional, Zalden, Peter, additional, Coffee, Ryan, additional, Thorwart, Michael, additional, and Bressler, Christian, additional

Published
2022
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27. Spin cascade and doming in Ferric Haems: Femtosecond X-ray Absorption and X-ray Emission Studies

Author

Bacellar, Camila, Kinschel, Dominik, Mancini, Giulia, Ingle, Rebecca, Rouxel, Jérémy, Cannelli, Oliviero, Cirelli, Claudio, Knopp, Gregor, Szlachetko, Jakub, Lima, Frederico, Menzi, Samuel, Pamfilidis, Georgios, Kubicek, Katharina, Khakhulin, Dmitry, Gawelda, Wojciech, Rodriguez-Fernandez, Angel, Biednov, Mykola, Bressler, Christian, Arrell, Christopher, Johnson, Philip, Milne, Christopher, and Chergui, Majed

Abstract

Processed XAS and XES data from the manuscript "Spin cascade and doming in Ferric Haems: Femtosecond X-ray Absorption and X-ray Emission Studies" and corresponding scripts used to analyse the data and produce the figures. Raw data generated at SwissFEL (PSI) and European XFEL

Published
2022
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28. Spin-state studies with XES and RIXS: From static to ultrafast

Author

Vankó, György, Bordage, Amélie, Glatzel, Pieter, Gallo, Erik, Rovezzi, Mauro, Gawelda, Wojciech, Galler, Andreas, Bressler, Christian, Doumy, Gilles, March, Anne Marie, Kanter, Elliot P., Young, Linda, Southworth, Stephen H., Canton, Sophie E., Uhlig, Jens, Smolentsev, Grigory, Sundström, Villy, Haldrup, Kristoffer, van Driel, Tim Brandt, Nielsen, Martin M., Kjaer, Kasper S., and Lemke, Henrik T.

Published
2013
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29. Tracking structural solvent reorganization and recombination dynamics following e− photoabstraction from aqueous I− with femtosecond x-ray spectroscopy and scattering

Author

Vester, Peter, Kubicek, Katharina, Alonso-Mori, Roberto, Assefa, Tadesse, Biasin, Elisa, Christensen, Morten, Dohn, Asmus O., van Driel, Tim B., Galler, Andreas, Gawelda, Wojciech, Harlang, Tobias C. B., Henriksen, Niels E., Kjær, Kasper S., Kuhlman, Thomas S., Németh, Zoltán, Nurekeyev, Zhangatay, Pápai, Mátyás, Rittman, Jochen, Vankó, György, Yavas, Hasan, Zederkof, Diana B., Bergmann, Uwe, Nielsen, Martin M., Møller, Klaus B., Haldrup, Kristoffer, Bressler, Christian, Vester, Peter, Kubicek, Katharina, Alonso-Mori, Roberto, Assefa, Tadesse, Biasin, Elisa, Christensen, Morten, Dohn, Asmus O., van Driel, Tim B., Galler, Andreas, Gawelda, Wojciech, Harlang, Tobias C. B., Henriksen, Niels E., Kjær, Kasper S., Kuhlman, Thomas S., Németh, Zoltán, Nurekeyev, Zhangatay, Pápai, Mátyás, Rittman, Jochen, Vankó, György, Yavas, Hasan, Zederkof, Diana B., Bergmann, Uwe, Nielsen, Martin M., Møller, Klaus B., Haldrup, Kristoffer, and Bressler, Christian

Abstract

We present a sub-picosecond resolved investigation of the structural solvent reorganization and geminate recombination dynamics following 400 nm two-photon excitation and photodetachment of a valence p electron from the aqueous atomic solute, I−(aq). The measurements utilized time-resolved X-ray Absorption Near Edge Structure (TR-XANES) spectroscopy and X-ray Solution Scattering (TR-XSS) at the Linac Coherent Light Source x-ray free electron laser in a laser pump/x-ray probe experiment. The XANES measurements around the L1-edge of the generated nascent iodine atoms (I0) yield an average electron ejection distance from the iodine parent of 7.4 ± 1.5 Å with an excitation yield of about 1/3 of the 0.1M NaI aqueous solution. The kinetic traces of the XANES measurement are in agreement with a purely diffusion-driven geminate iodine–electron recombination model without the need for a long-lived (I0:e−) contact pair. Nonequilibrium classical molecular dynamics simulations indicate a delayed response of the caging H2O solvent shell and this is supported by the structural analysis of the XSS data: We identify a two-step process exhibiting a 0.1 ps delayed solvent shell reorganization time within the tight H-bond network and a 0.3 ps time constant for the mean iodine–oxygen distance changes. The results indicate that most of the reorganization can be explained classically by a transition from a hydrophilic cavity with a well-ordered first solvation shell (hydrogens pointing toward I−) to an expanded cavity around I0 with a more random orientation of the H2O molecules in a broadened first solvation shell.

Published
2022

30. Tracking excited-state charge and spin dynamics in iron coordination complexes

Author

Zhang, Wenkai, Alonso-Mori, Roberto, Bergmann, Uwe, Bressler, Christian, Chollet, Matthieu, Galler, Andreas, Gawelda, Wojciech, Hadt, Ryan G., Hartsock, Robert W., Kroll, Thomas, Kjasr, Kasper S., Kubicek, Katharina, Lemke, Henrik T., Liang, Huiyang W., Meyer, Drew A., Nielsen, Martin M., Purser, Carola, Robinson, Joseph S., Solomon, Edward I., Sun, Zheng, Sokaras, Dimosthenis, van Driel, Tim B., Vanko, Gyorgy, Weng, Tsu-Chien, Zhu, Diling, and Gaffney, Kelly J.

Subjects
Electron spin -- Measurement, Coordination compounds -- Atomic properties, Excited state chemistry -- Research, Chemical research, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Crucial to many light-driven processes in transition metal complexes is the absorption and dissipation of energy by 3d electrons (1-4). But a detailed understanding of such non-equilibrium excited-state dynamics and [...]

Published
2014

31. Molecular Structural Dynamics Probed by Ultrafast X-Ray Absorption Spectroscopy

Author

Bressler, Christian and Chergui, Majed

Subjects
Chemistry
Abstract

Byline: Christian Bressler, Deutsches Elektronen-Synchrotron, 22607 Hamburg, Germany; email: Christian.bressler@xfel.eu; Majed Chergui, Ecole Polytechnique Federale de Lausanne, Laboratoire de Spectroscopie Ultrarapide, ISIC, Faculte des Sciences de Base, Station 6, CH-1015 Lausanne, Switzerland; email: Majed.chergui@epfl.ch Keywords: EXAFS, XANES, metal complexes, electron transfer, spin dynamics, solvation dynamics Abstract The ability to visualize molecular structure in the course of a chemical reaction or a biological function has been a dream of scientists for decades. X-ray absorption spectroscopy (XAS) is ideal in this respect because it is chemically selective and can be implemented in any type of medium. Furthermore, using X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) in laser pump/X-ray probe experiments allows the retrieval of not only the local geometric structure of the system under study, but also the underlying electronic structure changes that drive the structural dynamics. We review recent developments in picosecond and femtosecond XAS applied to molecular systems in solution. Examples on ultrafast photoinduced processes such as intramolecular electron transfer, low-to-high spin change, and bond formation are presented.

Published
2010

32. Site‐Selective Real‐Time Observation of Bimolecular Electron Transfer in a Photocatalytic System Using L‐Edge X‐Ray Absorption Spectroscopy**

Author

Britz, Alexander, primary, Bokarev, Sergey I., additional, Assefa, Tadesse A., additional, Bajnóczi, Èva G., additional, Németh, Zoltán, additional, Vankó, György, additional, Rockstroh, Nils, additional, Junge, Henrik, additional, Beller, Matthias, additional, Doumy, Gilles, additional, March, Anne Marie, additional, Southworth, Stephen H., additional, Lochbrunner, Stefan, additional, Kühn, Oliver, additional, Bressler, Christian, additional, and Gawelda, Wojciech, additional

Published
2021
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33. Ultrafast nonadiabatic dynamics of [[[Fe.sup.II][(bpy).sub.3]].sup.2+] in solution

Author

Gawelda, Wojciech, Cannizzo, Andrea, Pham, Van-Thai, Bressler, Christian, Van Mourik, Frank, and Chergui, Majed

Subjects
Pyridine -- Chemical properties, Pyridine -- Structure, Iron compounds -- Chemical properties, Iron compounds -- Structure, Relaxation phenomena -- Research, Chemistry
Abstract

Femtosecond fluorescence up-conversion and transient absorption (TA) studies are used for characterizing the ultrafast relaxation of aqueous iron(II)-tris(bipyridine) upon excitation into the singlet metal-to-ligand charge-transfer band (MLCT). A simple model of avoided crossings between singlet and triplet potential curves is proposed that is induced by the strong spin-orbit interaction.

Published
2007

34. Revealing Hot and Long-Lived Metastable Spin States in the Photoinduced Switching of Solvated Metallogrid Complexes with Femtosecond Optical and X-ray Spectroscopies

Author

Naumova, Maria A, Kalinko, Aleksandr, Wong, Joanne W L, Abdellah, Mohamed, Geng, Huifang, Domenichini, Edoardo, Meng, Jie, Gutierrez Alvarez, Sol Laura, Mante, Pierre-Adrien, Lin, Weihua, Zalden, Peter, Galler, Andreas, Lima, Frederico, Kubicek, Katharina, Biednov, Mykola, Britz, Alexander, Checchia, Stefano, Kabanova, Victoria, Wulff, Michael, Zimara, Jennifer, Schwarzer, Dirk, Demeshko, Serhiy, Murzin, Vadim, Gosztola, David, Jarenmark, Martin, Zhang, Jianxin, Bauer, Matthias, Lawson Daku, Max Latevi, Gawelda, Wojciech, Khakhulin, Dmitry, Bressler, Christian, Meyer, Franc, Zheng, Kaibo, Canton, Sophie E., Naumova, Maria A, Kalinko, Aleksandr, Wong, Joanne W L, Abdellah, Mohamed, Geng, Huifang, Domenichini, Edoardo, Meng, Jie, Gutierrez Alvarez, Sol Laura, Mante, Pierre-Adrien, Lin, Weihua, Zalden, Peter, Galler, Andreas, Lima, Frederico, Kubicek, Katharina, Biednov, Mykola, Britz, Alexander, Checchia, Stefano, Kabanova, Victoria, Wulff, Michael, Zimara, Jennifer, Schwarzer, Dirk, Demeshko, Serhiy, Murzin, Vadim, Gosztola, David, Jarenmark, Martin, Zhang, Jianxin, Bauer, Matthias, Lawson Daku, Max Latevi, Gawelda, Wojciech, Khakhulin, Dmitry, Bressler, Christian, Meyer, Franc, Zheng, Kaibo, and Canton, Sophie E.

Abstract

An atomistic understanding of the photoinduced spin-state switching (PSS) within polynuclear systems of d4-d7 transition metal ion complexes is required for their rational integration into light-driven reactions of chemical and biological interest. However, in contrast to mononuclear systems, the multidimensional dynamics of the PSS in solvated molecular arrays have not yet been elucidated due to the expected complications associated with the connectivity between the metal centers and the strong interactions with the surroundings. In this work, the PSS in a solvated triiron(II) metallogrid complex is characterized using transient optical absorption and X-ray emission spectroscopies on the femtosecond time scale. The complementary measurements reveal the photoinduced creation of energy-rich (hot) and long-lived quintet states, whose dynamics differ critically from their mononuclear congeners. This finding opens major prospects for developing novel schemes in solution-phase spin chemistry that are driven by the dynamic PSS process in compact oligometallic arrays.

Published
2020

35. Exploring the light-induced dynamics in solvated metallogrid complexes with femtosecond pulses across the electromagnetic spectrum

Author

Naumova, Maria A, Kalinko, Aleksandr, Wong, Joanne W L, Alvarez Gutierrez, Sol Laura, Meng, Jie, Liang, Mingli, Abdellah, Mohamed, Geng, Huifang, Lin, Weihua, Kubicek, Katharina, Biednov, Mykola, Lima, Frederico, Galler, Andreas, Zalden, Peter, Checchia, Stefano, Mante, Pierre-Adrien, Zimara, Jennifer, Schwarzer, Dirk, Demeshko, Serhiy, Murzin, Vadim, Gosztola, David, Jarenmark, Martin, Zhang, Jianxin, Bauer, Matthias, Lawson Daku, Max Latevi, Khakhulin, Dmitry, Gawelda, Wojciech, Bressler, Christian, Meyer, Franc, Zheng, Kaibo, Canton, Sophie E, Naumova, Maria A, Kalinko, Aleksandr, Wong, Joanne W L, Alvarez Gutierrez, Sol Laura, Meng, Jie, Liang, Mingli, Abdellah, Mohamed, Geng, Huifang, Lin, Weihua, Kubicek, Katharina, Biednov, Mykola, Lima, Frederico, Galler, Andreas, Zalden, Peter, Checchia, Stefano, Mante, Pierre-Adrien, Zimara, Jennifer, Schwarzer, Dirk, Demeshko, Serhiy, Murzin, Vadim, Gosztola, David, Jarenmark, Martin, Zhang, Jianxin, Bauer, Matthias, Lawson Daku, Max Latevi, Khakhulin, Dmitry, Gawelda, Wojciech, Bressler, Christian, Meyer, Franc, Zheng, Kaibo, and Canton, Sophie E

Abstract

Oligonuclear complexes of d4-d7 transition metal ion centers that undergo spin-switching have long been developed for their practical role in molecular electronics. Recently, they also have appeared as promising photochemical reactants demonstrating improved stability. However, the lack of knowledge about their photophysical properties in the solution phase compared to mononuclear complexes is currently hampering their inclusion into advanced light-driven reactions. In the present study, the ultrafast photoinduced dynamics in a solvated [2 × 2] iron(II) metallogrid complex are characterized by combining measurements with transient optical-infrared absorption and x-ray emission spectroscopy on the femtosecond time scale. The analysis is supported by density functional theory calculations. The photocycle can be described in terms of intra-site transitions, where the FeII centers in the low-spin state are independently photoexcited. The Franck-Condon state decays via the formation of a vibrationally hot high-spin (HS) state that displays coherent behavior within a few picoseconds and thermalizes within tens of picoseconds to yield a metastable HS state living for several hundreds of nanoseconds. Systematic comparison with the closely related mononuclear complex [Fe(terpy)2]2+ reveals that nuclearity has a profound impact on the photoinduced dynamics. More generally, this work provides guidelines for expanding the integration of oligonuclear complexes into new photoconversion schemes that may be triggered by ultrafast spin-switching.

Published
2020

36. Electronic and molecular structure of photoexcited [Ru(super II)(pby)3](super 2+) probed by picosecond X-ray absorption spectroscopy

Author

Gawelda, Wojciech, Johnson, Melanie, De Groot, Frank M.F., Abela, Rafael, Bressler, Christian, and Chergui, Majed

Subjects
Ruthenium -- Chemical properties, Molecular structure -- Analysis, Absorption spectra -- Analysis, Chemistry
Abstract

A detailed analysis of the electronic and molecular structure of the ground and excited states of [Ru(super II)(bpy)(sub 3)](super 2+) through static and picosecond-resolved X-ray absorption spectroscopy is presented. A Ru-N bond contraction by approximately 0.03 Angstrom in the excited-state complex, as compared to the ground-state compound is obtained which results from electrostatic and polarization contributions, limited by steric constraints on the bpy ligands.d

Published
2006

37. Ultrafast X-ray absorption spectroscopy

Author

Bressler, Christian and Chergui, Majed

Subjects
Absorption spectra -- Usage, Absorption spectra -- Research, Chemistry
Abstract

The high potential and current status of the research involving the use of ultrafast X-ray absorption spectroscopy (XAS), the boundary conditions of the technique and the implementation of XAS, is presented. XAS helps in providing the electronic and structural information on the system.

Published
2004

38. Femtosecond X-ray emission study of the spin cross-over dynamics in haem proteins

Author

Kinschel, Dominik, primary, Bacellar, Camila, additional, Cannelli, Oliviero, additional, Sorokin, Boris, additional, Katayama, Tetsuo, additional, Mancini, Giulia F., additional, Rouxel, Jérémy R., additional, Obara, Yuki, additional, Nishitani, Junichi, additional, Ito, Hironori, additional, Ito, Terumasa, additional, Kurahashi, Naoya, additional, Higashimura, Chika, additional, Kudo, Shotaro, additional, Keane, Theo, additional, Lima, Frederico A., additional, Gawelda, Wojciech, additional, Zalden, Peter, additional, Schulz, Sebastian, additional, Budarz, James M., additional, Khakhulin, Dmitry, additional, Galler, Andreas, additional, Bressler, Christian, additional, Milne, Christopher J., additional, Penfold, Thomas, additional, Yabashi, Makina, additional, Suzuki, Toshinori, additional, Misawa, Kazuhiko, additional, and Chergui, Majed, additional

Published
2020
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39. Exploring the light-induced dynamics in solvated metallogrid complexes with femtosecond pulses across the electromagnetic spectrum

Author

Naumova, Maria A., primary, Kalinko, Aleksandr, additional, Wong, Joanne W. L., additional, Alvarez Gutierrez, Sol, additional, Meng, Jie, additional, Liang, Mingli, additional, Abdellah, Mohamed, additional, Geng, Huifang, additional, Lin, Weihua, additional, Kubicek, Katharina, additional, Biednov, Mykola, additional, Lima, Frederico, additional, Galler, Andreas, additional, Zalden, Peter, additional, Checchia, Stefano, additional, Mante, Pierre-Adrien, additional, Zimara, Jennifer, additional, Schwarzer, Dirk, additional, Demeshko, Serhiy, additional, Murzin, Vadim, additional, Gosztola, David, additional, Jarenmark, Martin, additional, Zhang, Jianxin, additional, Bauer, Matthias, additional, Lawson Daku, Max Latevi, additional, Khakhulin, Dmitry, additional, Gawelda, Wojciech, additional, Bressler, Christian, additional, Meyer, Franc, additional, Zheng, Kaibo, additional, and Canton, Sophie E., additional

Published
2020
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40. Publisher’s Note: Femtosecond X-Ray Scattering Study of Ultrafast Photoinduced Structural Dynamics in Solvated [Co(terpy)2]2+ [Phys. Rev. Lett. 117 , 013002 (2016)]

Author

Biasin, Elisa, primary, van Driel, Tim Brandt, additional, Kjer, Kasper S., additional, Dohn, Asmus O., additional, Christensen, Morten, additional, Harlang, Tobias, additional, Vester, Peter, additional, Chabera, Pavel, additional, Liu, Yizhu, additional, Uhlig, Jens, additional, Papai, Matyas, additional, Nemeth, Zoltan, additional, Hartsock, Robert, additional, Liang, Winnie, additional, Zhang, Jianxin, additional, Alonso-Mori, Roberto, additional, Chollet, Matthieu, additional, Glownia, James M., additional, Nelson, Silke, additional, Sokaras, Dimosthenis, additional, Assefa, Tadesse A., additional, Britz, Alexander, additional, Galler, Andreas, additional, Gawelda, Wojciech, additional, Bressler, Christian, additional, Gaffney, Kelly J., additional, Lemke, Henrik T., additional, Moller, Klaus B., additional, Nielsen, Martin M., additional, Sundstrom, Villy, additional, Vanko, Gyorgy, additional, Warnmark, Kenneth, additional, Canton, Sophie E., additional, and Haldrup, Kristoffer, additional

Published
2020
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41. Revealing Hot and Long-Lived Metastable Spin States in the Photoinduced Switching of Solvated Metallogrid Complexes with Femtosecond Optical and X-ray Spectroscopies

Author

Naumova, Maria A., primary, Kalinko, Aleksandr, additional, Wong, Joanne W. L., additional, Abdellah, Mohamed, additional, Geng, Huifang, additional, Domenichini, Edoardo, additional, Meng, Jie, additional, Gutierrez, Sol Alvarez, additional, Mante, Pierre-Adrien, additional, Lin, Weihua, additional, Zalden, Peter, additional, Galler, Andreas, additional, Lima, Frederico, additional, Kubicek, Katharina, additional, Biednov, Mykola, additional, Britz, Alexander, additional, Checchia, Stefano, additional, Kabanova, Victoria, additional, Wulff, Michael, additional, Zimara, Jennifer, additional, Schwarzer, Dirk, additional, Demeshko, Serhiy, additional, Murzin, Vadim, additional, Gosztola, David, additional, Jarenmark, Martin, additional, Zhang, Jianxin, additional, Bauer, Matthias, additional, Lawson Daku, Max Latevi, additional, Gawelda, Wojciech, additional, Khakhulin, Dmitry, additional, Bressler, Christian, additional, Meyer, Franc, additional, Zheng, Kaibo, additional, and Canton, Sophie E., additional

Published
2020
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42. Ultrafast X-ray Photochemistry at European XFEL: Capabilities of the Femtosecond X-ray Experiments (FXE) Instrument

Author

Khakhulin, Dmitry, primary, Otte, Florian, additional, Biednov, Mykola, additional, Bömer, Christina, additional, Choi, Tae-Kyu, additional, Diez, Michael, additional, Galler, Andreas, additional, Jiang, Yifeng, additional, Kubicek, Katharina, additional, Lima, Frederico Alves, additional, Rodriguez-Fernandez, Angel, additional, Zalden, Peter, additional, Gawelda, Wojciech, additional, and Bressler, Christian, additional

Published
2020
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43. Heme Doming in Ferric Cytochrome c: Femtosecond X-ray Absorption and X-ray Emission Studies

Author

Bacellar, Camila, primary, Kinschel, Dominik, additional, Mancini, Giulia F., additional, Ingle, Rebecca A., additional, Rouxel, Jérémy, additional, Cannelli, Oliviero, additional, Cirelli, Claudio, additional, Knopp, Gregor, additional, Szlachetko, Jakub, additional, Lima, Frederico A., additional, Menzi, Samuel, additional, Pamfilidis, Georgios, additional, Kubicek, Katharina, additional, Khakhulin, Dmitry, additional, Gawelda, Wojciech, additional, Rodriguez-Fernandez, Angel, additional, Biednov, Mykola, additional, Bressler, Christian, additional, Arrell, Christopher A., additional, Johnson, Philip J. M., additional, Milne, Christopher, additional, and Chergui, Majed, additional

Published
2020
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44. Using Ultrafast X-ray Spectroscopy To Address Questions in Ligand-Field Theory: The Excited State Spin and Structure of [Fe(dcpp)2]2

Author

Britz, Alexander, Gawelda, Wojciech, Assefa, Tadesse A., Jamula, Lindsey L., Yarranton, Jonathan T., Galler, Andreas, Khakhulin, Dmitry, Diez, Michael, Harder, Manuel, Doumy, Gilles, March, Anne Marie, Bajnóczi, Éva, Németh, Zoltán, Pápai, Mátyás Imre, Rozsályi, Emese, Sárosiné Szemes, Dorottya, Cho, Hana, Mukherjee, Sriparna, Liu, Chang, Kim, Tae Kyu, Schoenlein, Robert W., Southworth, Stephen H., Young, Linda, Jakubikova, Elena, Huse, Nils, Vankó, György, Bressler, Christian, McCusker, James K., Britz, Alexander, Gawelda, Wojciech, Assefa, Tadesse A., Jamula, Lindsey L., Yarranton, Jonathan T., Galler, Andreas, Khakhulin, Dmitry, Diez, Michael, Harder, Manuel, Doumy, Gilles, March, Anne Marie, Bajnóczi, Éva, Németh, Zoltán, Pápai, Mátyás Imre, Rozsályi, Emese, Sárosiné Szemes, Dorottya, Cho, Hana, Mukherjee, Sriparna, Liu, Chang, Kim, Tae Kyu, Schoenlein, Robert W., Southworth, Stephen H., Young, Linda, Jakubikova, Elena, Huse, Nils, Vankó, György, Bressler, Christian, and McCusker, James K.

Abstract

We have employed a range of ultrafast X-ray spectroscopies in an effort to characterize the lowest energy excited state of [Fe(dcpp)2]2+ (where dcpp is 2,6-(dicarboxypyridyl)pyridine). This compound exhibits an unusually short excited-state lifetime for a low-spin Fe(II) polypyridyl complex of 270 ps in a room-temperature fluid solution, raising questions as to whether the ligand-field strength of dcpp had pushed this system beyond the 5T2/3T1 crossing point and stabilizing the latter as the lowest energy excited state. Kα and Kβ X-ray emission spectroscopies have been used to unambiguously determine the quintet spin multiplicity of the long-lived excited state, thereby establishing the 5T2 state as the lowest energy excited state of this compound. Geometric changes associated with the photoinduced ligand-field state conversion have also been monitored with extended X-ray absorption fine structure. The data show the typical average Fe-ligand bond length elongation of ∼0.18 Å for a 5T2 state and suggest a high anisotropy of the primary coordination sphere around the metal center in the excited 5T2 state, in stark contrast to the nearly perfect octahedral symmetry that characterizes the low-spin 1A1 ground state structure. This study illustrates how the application of time-resolved X-ray techniques can provide insights into the electronic structures of molecules-in particular, transition metal complexes-that are difficult if not impossible to obtain by other means.

Published
2019

45. Combining X-ray K beta(1,3), valence-to-core, and X-ray Raman spectroscopy for studying Earth materials at high pressure and temperature

Author

Weis, Christopher, Spiekermann, Georg (Dr. rer. nat.), Sternemann, Christian, Harder, Manuel, Vanko, Gyorgy, Cerantola, Valerio, Sahle, Christoph J., Forov, Yury, Sakrowski, Robin, Kupenko, Ilya, Petitgirard, Sylvain, Yavas, Hasan, Bressler, Christian, Gawelda, Wojciech, Tolan, Metin, and Wilke, Max (Prof. Dr.)

Subjects
ddc:550, Institut für Geowissenschaften
Abstract

X-ray emission and X-ray Raman scattering spectroscopy are powerful tools to investigate the local electronic and atomic structure of high and low Z elements in situ. Notably, these methods can be applied for in situ spectroscopy at high pressure and high temperature using resistively or laser-heated diamond anvil cells in order to achieve thermodynamic conditions which appear in the Earth's interior. We present a setup for combined X-ray emission and X-ray Raman scattering studies at beamline P01 of PETRA III using a portable wavelength-dispersive von Hamos spectrometer together with the permanently installed multiple-analyzer Johann-type spectrometer. The capabilities of this setup are exemplified by investigating the iron spin crossover of siderite FeCO3 up to 49.3 GPa by measuring the Fe M2,3-edge and the Fe Kβ1,3 emission line simultaneously. With this setup, the Fe valence-to-core emission can be detected together with the Kβ1,3 emission line providing complementary information on the sample's electronic structure. By implementing a laser-heating device, we demonstrate the strength of using a von Hamos type spectrometer for spin state mapping at extreme conditions. Finally, we give different examples of low Z elements' absorption edges relevant for application in geoscience that are accessible with the Johann-type XRS spectrometer. With this setup new insights into the spin transition and compression mechanisms of Earth's mantle materials can be obtained of importance for comprehension of the macroscopic physical and chemical properties of the Earth's interior.

Published
2018

46. Structural dynamics upon photoexcitation-induced charge transfer in a dicopper($\mathrm{_I}$)–disulfide complex

Author

Naumova, Maria, Khakhulin, Dmitry, Rebarz, Mateusz, Rohrmüller, Martin, Dicke, Benjamin, Biednov, Mykola, Britz, Alexander, Espinoza, Shirly, Grimm-Lebsanft, Benjamin, Kloz, Miroslav, Kretzschmar, Norman, Neuba, Adam, Ortmeyer, Jochen, Schoch, Roland, Andreasson, Jakob, Bauer, Matthias, Bressler, Christian, Gero Schmidt, Wolf, Henkel, Gerald, and Rübhausen, Michael

Subjects
ddc:540
Abstract

Physical chemistry, chemical physics 20(9), 6274 - 6286 (2018). doi:10.1039/C7CP04880G, The structural dynamics of charge-transfer states of nitrogen-ligated copper complexes has been extensively investigated in recent years following the development of pump–probe X-ray techniques. In this study we extend this approach towards copper complexes with sulfur coordination and investigate the influence of charge transfer states on the structure of a dicopper(I) complex with coordination by bridging disulfide ligands and additionally tetramethylguanidine units [Cu$^{I}$$_{2}$(NSSN)$_2$]$^{2+}$. In order to directly observe and refine the photoinduced structural changes in the solvated complex we applied picosecond pump–probe X-ray absorption spectroscopy (XAS) and wide-angle X-ray scattering (WAXS). Additionally, the ultrafast evolution of the electronic excited states was monitored by femtosecond transient absorption spectroscopy in the UV-Vis probe range. DFT calculations were used to predict molecular geometries and electronic structures of the ground and metal-to-ligand charge transfer states with singlet and triplet spin multiplicities, i.e. S$_0$, $^1$MLCT and $^3$MLCT, respectively. Combining these techniques we elucidate the electronic and structural dynamics of the solvated complex upon photoexcitation to the MLCT states. In particular, femtosecond optical transient spectroscopy reveals three distinct timescales of 650 fs, 10 ps and >100 ps, which were assigned as internal conversion to the ground state (S$_n$ → S$_0$), intersystem crossing $^1$MLCT → $^3$MLCT, and subsequent relaxation of the triplet to the ground state, respectively. Experimental data collected using both X-ray techniques are in agreement with the DFT-predicted structure for the triplet state, where coordination bond lengths change and one of the S–S bridges is cleaved, causing the movement of two halves of the molecule relative to each other. Extended X-ray absorption fine structure spectroscopy resolves changes in Cu–ligand bond lengths with precision on the order of 0.01 Å, whereas WAXS is sensitive to changes in the global shape related to relative movement of parts of the molecule. The results presented herein widen the knowledge on the electronic and structural dynamics of photoexcited copper–sulfur complexes and demonstrate the potential of combining the pump–probe X-ray absorption and scattering for studies on photoinduced structural dynamics in copper-based coordination complexes., Published by RSC Publ., Cambridge

Published
2018
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48. Scientific instrument Femtosecond X-ray Experiments (FXE): instrumentation and baseline experimental capabilities

Author

Galler, Andreas, primary, Gawelda, Wojciech, additional, Biednov, Mykola, additional, Bomer, Christina, additional, Britz, Alexander, additional, Brockhauser, Sandor, additional, Choi, Tae-Kyu, additional, Diez, Michael, additional, Frankenberger, Paul, additional, French, Marcus, additional, Görries, Dennis, additional, Hart, Matthiew, additional, Hauf, Steffen, additional, Khakhulin, Dmitry, additional, Knoll, Martin, additional, Korsch, Timo, additional, Kubicek, Katharina, additional, Kuster, Markus, additional, Lang, Philipp, additional, Alves Lima, Frederico, additional, Otte, Florian, additional, Schulz, Sebastian, additional, Zalden, Peter, additional, and Bressler, Christian, additional

Published
2019
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49. Using Ultrafast X-ray Spectroscopy To Address Questions in Ligand-Field Theory: The Excited State Spin and Structure of [Fe(dcpp)2]2+

Author

Britz, Alexander, primary, Gawelda, Wojciech, additional, Assefa, Tadesse A., additional, Jamula, Lindsey L., additional, Yarranton, Jonathan T., additional, Galler, Andreas, additional, Khakhulin, Dmitry, additional, Diez, Michael, additional, Harder, Manuel, additional, Doumy, Gilles, additional, March, Anne Marie, additional, Bajnóczi, Éva, additional, Németh, Zoltán, additional, Pápai, Mátyás, additional, Rozsályi, Emese, additional, Sárosiné Szemes, Dorottya, additional, Cho, Hana, additional, Mukherjee, Sriparna, additional, Liu, Chang, additional, Kim, Tae Kyu, additional, Schoenlein, Robert W., additional, Southworth, Stephen H., additional, Young, Linda, additional, Jakubikova, Elena, additional, Huse, Nils, additional, Vankó, György, additional, Bressler, Christian, additional, and McCusker, James K., additional

Published
2019
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