Femtosecond X-ray Absorption Spectroscopy at a Hard X-ray Free Electron Laser: Application to Spin Crossover Dynamics

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• 作者：Henrik T. Lemke ; Christian Bressler ; Lin X. Chen ; David M. Fritz ; Kelly J. Gaffney ; Andreas Galler ; Wojciech Gawelda ; Kristoffer Haldrup ; Robert W. Hartsock ; Hyotcherl Ihee ; Jeongho Kim ; Kyung Hwan Kim ; Jae Hyuk Lee ; Martin M. Nielsen ; Andrew B. Stickrath ; Wenkai Zhang ; Diling Zhu ; Marco Cammarata
• 刊名：The Journal of Physical Chemistry A
• 出版年：2013
• 出版时间：January 31, 2013
• 年：2013
• 卷：117
• 期：4
• 页码：735-740
• 全文大小：293K
• 年卷期：v.117,no.4(January 31, 2013)
• ISSN：1520-5215

文摘

X-ray free electron lasers (XFELs) deliver short (<100 fs) and intense (10¹² 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鈥?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 160 fs.