Lemke, Henrik T.3; Bressler, Christian4; Chen, Lin X.9; Fritz, David M.3; Gaffney, Kelly J.3; Galler, Andreas4; Gawelda, Wojciech4; Haldrup, Martin Kristoffer1; Hartsock, Robert W.3; Ihee, Hyotcherl10; Kim, Jeongho11; Kim, Kyung Hwan10; Lee, Jae Hyuk8; Nielsen, Martin Meedom1; Stickrath, Andrew B.9; Zhang, Wenkai3; Zhu, Diling3; Cammarata, Marco3
1 Department of Physics, Technical University of Denmark2 Neutrons and X-rays for Materials Physics, Department of Physics, Technical University of Denmark3 SLAC National Accelerator Laboratory4 European XFEL5 Argonne National Laboratory6 Korea Basic Science Institute7 Inha University8 Korea Advanced Institute of Science & Technology9 Argonne National Laboratory10 Korea Basic Science Institute11 Inha University
Application to Spin Crossover Dynamics
X-ray free electron lasers (XFELs) deliver short (<100 fs) and intense (similar to 10(12) photons) pulses of hard X-rays, making them excellent sources for time-resolved studies. Here we show that, despite the inherent instabilities of current (SASE based) XFELs, they can be used for measuring high-quality X-ray absorption data and we report femtosecond time-resolved X-ray absorption near-edge spectroscopy (XANES) measurements of a spin-crossover system, iron(II) tris(2,2'-bipyridine) in water. The data indicate that the low-spin to high-spin transition can be modeled by single-exponential kinetics convoluted with the overall time resolution. The resulting time constant is similar to 160 fs.
Journal of Physical Chemistry a, 2013, Vol 117, Issue 4, p. 735-740