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 - 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 -