TY - JOUR A1 - Kubin, Markus A1 - Kern, Jan A1 - Gul, Sheraz A1 - Kroll, Thomas A1 - Chatterjee, Ruchira A1 - Loechel, Heike A1 - Fuller, Franklin D. A1 - Sierra, Raymond G. A1 - Quevedo, Wilson A1 - Weniger, Christian A1 - Rehanek, Jens A1 - Firsov, Anatoly A1 - Laksmono, Hartawan A1 - Weninger, Clemens A1 - Alonso-Mori, Roberto A1 - Nordlund, Dennis L. A1 - Lassalle-Kaiser, Benedikt A1 - Glownia, James M. A1 - Krzywinski, Jacek A1 - Moeller, Stefan A1 - Turner, Joshua J. A1 - Minitti, Michael P. A1 - Dakovski, Georgi L. A1 - Koroidov, Sergey A1 - Kawde, Anurag A1 - Kanady, Jacob S. A1 - Tsui, Emily Y. A1 - Suseno, Sandy A1 - Han, Zhiji A1 - Hill, Ethan A1 - Taguchi, Taketo A1 - Borovik, Andrew S. A1 - Agapie, Theodor A1 - Messinger, Johannes A1 - Erko, Alexei A1 - Föhlisch, Alexander A1 - Bergmann, Uwe A1 - Mitzner, Rolf A1 - Yachandra, Vittal K. A1 - Yano, Junko A1 - Wernet, Philippe T1 - Soft x-ray absorption spectroscopy of metalloproteins and high-valent metal-complexes at room temperature using free-electron lasers JF - Structural dynamics N2 - X-ray absorption spectroscopy at the L-edge of 3d transition metals provides unique information on the local metal charge and spin states by directly probing 3d-derived molecular orbitals through 2p-3d transitions. However, this soft x-ray technique has been rarely used at synchrotron facilities for mechanistic studies of metalloenzymes due to the difficulties of x-ray-induced sample damage and strong background signals from light elements that can dominate the low metal signal. Here, we combine femtosecond soft x-ray pulses from a free-electron laser with a novel x-ray fluorescence-yield spectrometer to overcome these difficulties. We present L-edge absorption spectra of inorganic high-valent Mn complexes (Mn similar to 6-15 mmol/l) with no visible effects of radiation damage. We also present the first L-edge absorption spectra of the oxygen evolving complex (Mn4CaO5) in Photosystem II (Mn < 1 mmol/l) at room temperature, measured under similar conditions. Our approach opens new ways to study metalloenzymes under functional conditions. (C) 2017 Author(s). Y1 - 2017 U6 - https://doi.org/10.1063/1.4986627 SN - 2329-7778 VL - 4 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Kunnus, Kristjan A1 - Josefsson, Ida A1 - Rajkovic, Ivan A1 - Schreck, Simon A1 - Quevedo, Wilson A1 - Beye, Martin A1 - Grübel, Sebastian A1 - Scholz, Mirko A1 - Nordlund, Dennis A1 - Zhang, Wenkai A1 - Hartsock, Robert W. A1 - Gaffney, Kelly J. A1 - Schlotter, William F. A1 - Turner, Joshua J. A1 - Kennedy, Brian A1 - Hennies, Franz A1 - Techert, Simone A1 - Wernet, Philippe A1 - Odelius, Michael A1 - Föhlisch, Alexander T1 - Anti-Stokes resonant x-ray Raman scattering for atom specific and excited state selective dynamics JF - NEW JOURNAL OF PHYSICS N2 - 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. KW - ultrafast photochemistry KW - excited state selectivity KW - anti-Stokes resonant x-ray raman scattering KW - free electron lasers KW - resonant inelastic x-ray scattering Y1 - 2016 U6 - https://doi.org/10.1088/1367-2630/18/10/103011 SN - 1367-2630 VL - 18 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Kroll, Thomas A1 - Kern, Jan A1 - Kubin, Markus A1 - Ratner, Daniel A1 - Gul, Sheraz A1 - Fuller, Franklin D. A1 - Löchel, Heike A1 - Krzywinski, Jacek A1 - Lutman, Alberto A1 - Ding, Yuantao A1 - Dakovski, Georgi L. A1 - Moeller, Stefan A1 - Turner, Joshua J. A1 - Alonso-Mori, Roberto A1 - Nordlund, Dennis L. A1 - Rehanek, Jens A1 - Weniger, Christian A1 - Firsov, Alexander A1 - Brzhezinskaya, Maria A1 - Chatterjee, Ruchira A1 - Lassalle-Kaiser, Benedikt A1 - Sierra, Raymond G. A1 - Laksmono, Hartawan A1 - Hill, Ethan A1 - Borovik, Andrew S. A1 - Erko, Alexei A1 - Föhlisch, Alexander A1 - Mitzner, Rolf A1 - Yachandra, Vittal K. A1 - Yano, Junko A1 - Wernet, Philippe A1 - Bergmann, Uwe T1 - X-ray absorption spectroscopy using a self-seeded soft X-ray free-electron laser JF - Optics express : the international electronic journal of optics N2 - X-ray free electron lasers (XFELs) enable unprecedented new ways to study the electronic structure and dynamics of transition metal systems. L-edge absorption spectroscopy is a powerful technique for such studies and the feasibility of this method at XFELs for solutions and solids has been demonstrated. However, the required x-ray bandwidth is an order of magnitude narrower than that of self-amplified spontaneous emission (SASE), and additional monochromatization is needed. Here we compare L-edge x-ray absorption spectroscopy (XAS) of a prototypical transition metal system based on monochromatizing the SASE radiation of the linac coherent light source (LCLS) with a new technique based on self-seeding of LCLS. We demonstrate how L-edge XAS can be performed using the self-seeding scheme without the need of an additional beam line monochromator. We show how the spectral shape and pulse energy depend on the undulator setup and how this affects the x-ray spectroscopy measurements. (C) 2016 Optical Society of America Y1 - 2016 U6 - https://doi.org/10.1364/OE.24.022469 SN - 1094-4087 VL - 24 SP - 22469 EP - 22480 PB - Optical Society of America CY - Washington ER - TY - JOUR A1 - Wernet, Philippe A1 - Kunnus, Kristjan A1 - Josefsson, Ida A1 - Rajkovic, Ivan A1 - Quevedo, Wilson A1 - Beye, Martin A1 - Schreck, Simon A1 - Gruebel, S. A1 - Scholz, Mirko A1 - Nordlund, Dennis A1 - Zhang, Wenkai A1 - Hartsock, Robert W. A1 - Schlotter, William F. A1 - Turner, Joshua J. A1 - Kennedy, Brian A1 - Hennies, Franz A1 - de Groot, Frank M. F. A1 - Gaffney, Kelly J. A1 - Techert, Simone A1 - Odelius, Michael A1 - Föhlisch, Alexander T1 - Orbital-specific mapping of the ligand exchange dynamics of Fe(CO)(5) in solution JF - Nature : the international weekly journal of science N2 - Transition-metal complexes have long attracted interest for fundamental chemical reactivity studies and possible use in solar energy conversion(1,2). Electronic excitation, ligand loss from the metal centre, or a combination of both, creates changes in charge and spin density at the metal site(3-11) that need to be controlled to optimize complexes for photocatalytic hydrogen production(8) and selective carbon-hydrogen bond activation(9-11). An understanding at the molecular level of how transition-metal complexes catalyse reactions, and in particular of the role of the short-lived and reactive intermediate states involved, will be critical for such optimization. However, suitable methods for detailed characterization of electronic excited states have been lacking. Here we show, with the use of X-ray laser-based femtosecond-resolution spectroscopy and advanced quantum chemical theory to probe the reaction dynamics of the benchmark transition-metal complex Fe(CO)(5) in solution, that the photo-induced removal of CO generates the 16-electron Fe(CO)(4) species, a homogeneous catalyst(12,13) with an electron deficiency at the Fe centre(14,15), in a hitherto unreported excited singlet state that either converts to the triplet ground state or combines with a CO or solvent molecule to regenerate a penta-coordinated Fe species on a sub-picosecond timescale. This finding, which resolves the debate about the relative importance of different spin channels in the photochemistry of Fe(CO)(5) (refs 4, 16-20), was made possible by the ability of femtosecond X-ray spectroscopy to probe frontier-orbital interactions with atom specificity. We expect the method to be broadly applicable in the chemical sciences, and to complement approaches that probe structural dynamics in ultrafast processes. Y1 - 2015 U6 - https://doi.org/10.1038/nature14296 SN - 0028-0836 SN - 1476-4687 VL - 520 IS - 7545 SP - 78 EP - 81 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Oberg, H. A1 - Gladh, Jörgen A1 - Anniyev, Toyli A1 - Beye, Martin A1 - Coffee, Ryan A1 - Föhlisch, Alexander A1 - Katayama, T. A1 - Kaya, Sarp A1 - LaRue, Jerry A1 - Mogelhoj, Andreas A1 - Nordlund, Dennis A1 - Ogasawara, Hirohito A1 - Schlotter, William F. A1 - Sellberg, Jonas A. A1 - Sorgenfrei, Florian A1 - Turner, Joshua J. A1 - Wolf, Martin A1 - Wurth, W. A1 - Ostrom, Henrik A1 - Nilsson, Anders A1 - Norskov, Jens K. A1 - Pettersson, Lars G. M. T1 - Optical laser-induced CO desorption from Ru(0001) monitored with a free-electron X-ray laser: DFT prediction and X-ray confirmation of a precursor state JF - Surface science N2 - We present density functional theory modeling of time-resolved optical pump/X-ray spectroscopic probe data of CO desorption from Ru(0001). The BEEF van der Waals functional predicts a weakly bound state as a precursor to desorption. The optical pump leads to a near-instantaneous (<100 fs) increase of the electronic temperature to nearly 7000 K. The temperature evolution and energy transfer between electrons, substrate phonons and adsorbate is described by the two-temperature model and found to equilibrate on a timescale of a few picoseconds to an elevated local temperature of similar to 2000K. Estimating the free energy based on the computed potential of mean force along the desorption path, we find an entropic barrier to desorption (and by time-reversal also to adsorption). This entropic barrier separates the chemisorbed and precursor states, and becomes significant at the elevated temperature of the experiment (similar to 1.4 eV at 2000 K). Experimental pump-probe X-ray absorption/X-ray emission spectroscopy indicates population of a precursor state to desorption upon laser-excitation of the system (Dell'Angela et al., 2013). Computing spectra along the desorption path confirms the picture of a weakly bound transient state arising from ultrafast heating of the metal substrate. (C) 2015 Elsevier B.V. All rights reserved. KW - CO desorption KW - Potential of mean force KW - Two-temperature model KW - Pump-probe KW - X-ray spectroscopy KW - Density functional theory Y1 - 2015 U6 - https://doi.org/10.1016/j.susc.2015.03.011 SN - 0039-6028 SN - 1879-2758 VL - 640 SP - 80 EP - 88 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Dell'Angela, Martina A1 - Anniyev, Toyli A1 - Beye, Martin A1 - Coffee, Ryan A1 - Föhlisch, Alexander A1 - Gladh, Jörgen A1 - Kaya, Sarp A1 - Katayama, Tetsuo A1 - Krupin, Oleg A1 - Nilsson, Anders A1 - Nordlund, Dennis A1 - Schlotter, William F. A1 - Sellberg, Jonas A. A1 - Sorgenfrei, Florian A1 - Turner, Joshua J. A1 - ÖstrÖm, Henrik A1 - Ogasawara, Hirohito A1 - Wolf, Martin A1 - Wurth, Wilfried T1 - Vacuum space charge effects in sub-picosecond soft X-ray photoemission on a molecular adsorbate layer JF - Structural dynamics N2 - Vacuum space charge induced kinetic energy shifts of O 1s and Ru 3d core levels in femtosecond soft X-ray photoemission spectra (PES) have been studied at a free electron laser (FEL) for an oxygen layer on Ru(0001). We fully reproduced the measurements by simulating the in-vacuum expansion of the photoelectrons and demonstrate the space charge contribution of the high-order harmonics in the FEL beam. Employing the same analysis for 400 nm pump-X-ray probe PES, we can disentangle the delay dependent Ru 3d energy shifts into effects induced by space charge and by lattice heating from the femtosecond pump pulse. (C) 2015 Author(s). Y1 - 2015 U6 - https://doi.org/10.1063/1.4914892 SN - 2329-7778 VL - 2 IS - 2 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Eckert, Sebastian A1 - Beye, Martin A1 - Pietzsch, Annette A1 - Quevedo, Wilson A1 - Hantschmann, Markus A1 - Ochmann, Miguel A1 - Ross, Matthew A1 - Minitti, Michael P. A1 - Turner, Joshua J. A1 - Moeller, Stefan P. A1 - Schlotter, William F. A1 - Dakovski, Georgi L. A1 - Khalil, Munira A1 - Huse, Nils A1 - Föhlisch, Alexander T1 - Principles of femtosecond X-ray/optical cross-correlation with X-ray induced transient optical reflectivity in solids JF - Applied physics letters N2 - The discovery of ultrafast X-ray induced optical reflectivity changes enabled the development of X-ray/optical cross correlation techniques at X-ray free electron lasers worldwide. We have now linked through experiment and theory the fundamental excitation and relaxation steps with the transient optical properties in finite solid samples. Therefore, we gain a thorough interpretation and an optimized detection scheme of X-ray induced changes to the refractive index and the X-ray/optical cross correlation response. (C) 2015 AIP Publishing LLC. Y1 - 2015 U6 - https://doi.org/10.1063/1.4907949 SN - 0003-6951 SN - 1077-3118 VL - 106 IS - 6 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Mitzner, Rolf A1 - Rehanek, Jens A1 - Kern, Jan A1 - Gul, Sheraz A1 - Hattne, Johan A1 - Taguchi, Taketo A1 - Alonso-Mori, Roberto A1 - Tran, Rosalie A1 - Weniger, Christian A1 - Schröder, Henning A1 - Quevedo, Wilson A1 - Laksmono, Hartawan A1 - Sierra, Raymond G. A1 - Han, Guangye A1 - Lassalle-Kaiser, Benedikt A1 - Koroidov, Sergey A1 - Kubicek, Katharina A1 - Schreck, Simon A1 - Kunnus, Kristjan A1 - Brzhezinskaya, Maria A1 - Firsov, Alexander A1 - Minitti, Michael P. A1 - Turner, Joshua J. A1 - Möller, Stefan A1 - Sauter, Nicholas K. A1 - Bogan, Michael J. A1 - Nordlund, Dennis A1 - Schlotter, William F. A1 - Messinger, Johannes A1 - Borovik, Andrew S. A1 - Techert, Simone A1 - de Groot, Frank M. F. A1 - Föhlisch, Alexander A1 - Erko, Alexei A1 - Bergmann, Uwe A1 - Yachandra, Vittal K. A1 - Wernet, Philippe A1 - Yano, Junko T1 - L-edge x-ray absorption spectroscopy of dilute systems relevant to metalloproteins using an X-ray free-electron laser JF - The journal of physical chemistry letters N2 - L-edge spectroscopy of 3d transition metals provides important electronic structure information and has been used in many fields. However, the use of this method for studying dilute aqueous systems, such as metalloenzymes, has not been prevalent because of severe radiation damage and the lack of suitable detection systems. Here we present spectra from a dilute Mn aqueous solution using a high-transmission zone-plate spectrometer at the Linac Coherent Light Source (LCLS). The spectrometer has been optimized for discriminating the Mn L-edge signal from the overwhelming 0 K-edge background that arises from water and protein itself, and the ultrashort LCLS X-ray pulses can outrun X-ray induced damage. We show that the deviations of the partial-fluorescence yield-detected spectra from the true absorption can be well modeled using the state-dependence of the fluorescence yield, and discuss implications for the application of our concept to biological samples. Y1 - 2013 U6 - https://doi.org/10.1021/jz401837f SN - 1948-7185 VL - 4 IS - 21 SP - 3641 EP - 3647 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Kunnus, Kristjan A1 - Rajkovic, Ivan A1 - Schreck, Simon A1 - Quevedo, Wilson A1 - Eckert, Sebastian A1 - Beye, Martin A1 - Suljoti, Edlira A1 - Weniger, Christian A1 - Kalus, Christian A1 - Gruebel, Sebastian A1 - Scholz, Mirko A1 - Nordlund, Dennis A1 - Zhang, Wenkai A1 - Hartsock, Robert W. A1 - Gaffney, Kelly J. A1 - Schlotter, William F. A1 - Turner, Joshua J. A1 - Kennedy, Brian A1 - Hennies, Franz A1 - Techert, Simone A1 - Wernet, Philippe A1 - Föhlisch, Alexander T1 - A setup for resonant inelastic soft x-ray scattering on liquids at free electron laser light sources JF - Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques N2 - 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. Y1 - 2012 U6 - https://doi.org/10.1063/1.4772685 SN - 0034-6748 VL - 83 IS - 12 PB - American Institute of Physics CY - Melville ER -