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Joint Inorganic-Electrochemistry Seminar/Chemical Physics Seminar

Monday, May 13, 2019
4:00pm to 5:00pm
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Noyes 147 (J. Holmes Sturdivant Lecture Hall)
What did the metal know, and when did she know it? Ultrafast XUV spectroscopy reveals short-lived states in transition metal complexes and organohalide perovskites
Josh Vura-Weis, Assistant Professor of Chemistry, Chemistry, University of Illinois Urbana-Champaign,

X-ray absorption near edge spectroscopy (XANES or NEXAFS) is a powerful technique for electronic structure determination. However, widespread use of XANES is limited by the need for synchrotron light sources with tunable x-ray energy. Recent developments in extreme ultraviolet (XUV) light sources using the laser-based technique of high-harmonic generation have enabled core-level spectroscopy to be performed on femtosecond to attosecond timescales. We have extended the scope of tabletop XUV spectroscopy and demonstrated that M2,3-edge XANES, corresponding to 3p→3d transitions, can reliably measure the electronic structure of first-row transition metal coordination complexes with femtosecond time resolution. We use this ability to track the excited-state relaxation pathways of photocatalysts and spin crossover complexes. In semiconductors such as CH3NH3PbI3, distinct signals are observed for photoinduced electrons and holes, allowing the dynamics of each carrier to be tracked independently. This work establishes extreme ultraviolet spectroscopy as a useful tool for mainstream research in inorganic, organometallic, and materials chemistry.

Please Note: The "2,3" in M2,3-edge is subscripted; the "3" in CH3NH3Pbl3 is subscripted.

For more information, please contact Patricia Anderson by phone at 626-395-6022 or by email at pea@caltech.edu.