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Science-related travel has slowed, and in some cases stopped in the US and many other countries. The slowing of research and research collaborations has a negative effect on our progress, but perhaps especially on our students. In this zoom-based journal club, our speakers will talk for about 25 minutes about some topic of their choice, and will provide some appropriate reading that the students and other participants should read ahead of time and have available. We'll try to record these zoom sessions and distribute without restriction. Hence, anyone who participates should expect that they are doing so in a public, recorded forum
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Past lectures are now on the YouTube Channel: tinyurl.com/XASvideos
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Next seminar: Thursday Jan 28 (9am Seattle)
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please email seidler@uw.edu to be added to the mailing list for the zoom links.
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Thursday January 28 20219am SeattleDugan HayesInvestigating irreversible photochemical reaction mechanisms using X-ray transient absorption spectroscopyWhile X-ray transient absorption spectroscopy (XTA) has been used to investigate homogeneous photophysical dynamics for over two decades [1], using this technique to study irreversible photochemical reactions introduces additional practical challenges [2]. I will present our recent XTA work on two photochemical systems and discuss how we were able to overcome those challenges for both cases. First, we have used XTA at the copper K-edge to study the Cu(I)-catalyzed intermolecular [2 + 2] photocycloaddition reaction [3] and have found it to proceed through an initial metal-to-ligand charge transfer (MLCT) state rather than the previously favored photocupration mechanism. We have also demonstrated that the subsequent steps in this reaction and the corresponding stereoselectivity strongly depend on the nature of the substrate(s) involved. By combining these results with optical transient absorption data, we have pieced together a picture of the entire mechanism following initial population of the MLCT state, including reverse electron transfer, C-C bond formation, and product dissociation. Next, we have used XTA at the iron K-edge to elucidate the mechanism of the photoinduced reduction of the ferrate ion in aqueous solution [4]. We have successfully identified the timescales, intermediates, and branching ratios for both the photophysical and photochemical pathways in ferrate following near-ultraviolet excitation and are currently extending this work to the investigation of downstream diffusion-limited intermolecular redox kinetics.[1] L. X. Chen and X. Zhang. “Photochemical Processes Revealed by X-ray Transient Absorption Spectroscopy.” J. Phys. Chem. Lett., 4, 4000-4013 (2013). DOI: 10.1021/jz401750g

[2] D. Moonshiram et al. “Tracking the Structural and Electronic Configurations of a Cobalt Proton Reduction Catalyst in Water.” J. Am. Chem. Soc., 138, 10586-10596 (2016).

[3] S. Poplata, A. Tröster, Y.-Q. Zou, and T. Bach. “Recent Advances in the Synthesis of Cyclobutanes by Olefin [2 + 2] Photocycloaddition Reactions.” Chem. Rev., 116, 9748-9815 (2016). DOI: 10.1021/acs.chemrev.5b00723

[4] V. K. Sharma. “Ferrate(VI) and ferrate(V) oxidation of organic compounds: Kinetics and mechanism.” Coord. Chem. Rev., 257, 495-510 (2013). DOI: 10.1016/j.ccr.2012.04.014
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FUTURE SEMINARS
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DateSpeakerTitleAbstractDOI's or links for paper(s)
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Thursday February 4 20219am SeattleKristina Kvashnina
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Thursday February 11 20219am Seattle
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Thursday February 18 20219am SeattleLuisa Whittaker-Brooks
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Thursday February 25 20219am SeattleRaffaella Torchio
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Thursday March 4 20219am SeattleWanli Yang
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Thursday March 11 20219am SeattleEdmund Welter
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Thursday March 18 20219am SeattleRafaella Georgiou
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Thursday March 25 20219am SeattleUwe BergmannXRF imaging
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Thursday April 1 20219am SeattleLiane Moreauactinide
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Thursday April 8 20219am SeattleMatjaz KavcicS XES
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Thursday April 15 20219am SeattleRoman Chernikovbeamline
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Thursday April 22 20219am SeattleJanis TimoshenkoML
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Thursday April 29 20219am SeattleDavid Shuhactinides
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Thursday May 6 20219am SeattleChi ChenML
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Thursday May 13 20219am SeattleKelly Chacon
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Thursday May 20 20219am Seattlecancelled
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Thursday May 27 20219am SeattleGabriel Man
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Thursday June 3 20219am SeattleMary UptonRIXS and ID-27
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Thursday June 10 20219am SeattleDaniel HaskelMagnetism at High Pressures: Search for Quantum Spin Liquids in 5d Oxides”
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Thursday June 17 20219am Seattle
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Thursday June 24 20219am Seattle(cancelled)
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Thursday July 1 20219am SeattleAlex FranoRIXs iridates, or similar
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Thursday July 8 20219am Seattle Gianluigi Botton
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Thursday July 15 20219am SeattleAditi Bjattercherjee
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Thursday July 22 20219am SeattleYang Ha
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Thursday July 29 20219am Seattle
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Thursday August 5 20219am Seattle
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Thursday August 12 20219am Seattle
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Thursday August 19 20219am SeattleElisa Biasin
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Thursday August 26 20219am SeattleMichael Mara
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Thursday September 2 20219am Seattle
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Thursday September 9 20219am SeattleJohn Rehr
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Thursday September 16 20219am SeattleSam WebbFrom Optics and Spectrometers to Adaptive Scanning – The Latest from the SSRL Spectroscopic Imaging Beamlines
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Thursday September 23 20219am SeattlePaula AbdalaCombined XAS-XRD studies to probe the structure and dynamics of heterogeneous catalysts across different length scales
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Thursday September 30 20219am SeattleNiri GovindX-ray Spectroscopy Studies of Molecules and Materials with TDDFT-Based Approaches: Recent Applications and Developments
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Thursday October 7 20219am SeattleSoham MukhergeeA 'local' structure perspective on the concept of Vegard's Law and chemical pressure in solids
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Thursday October 14 20219am SeattleKelly SummersX-Ray Absorption Spectroscopy in Understanding and Treating Alzheimer’s Disease
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Thursday October 21 20219am SeattleCarolyn PearceUnraveling the Spectroscopic Signatures of Nuclear Waste
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Thursday October 28 20219am SeattleHudson CarvalhoXAS in plant science: challenges to move from ex situ to in vivo conditions
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Thursday November 4 20219am SeattleMichael BakerX-ray absorption, XMCD and RIXS of transition metal single-ion magnets: an analysis of 3d-4s mixing and spin-orbit coupling
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Thursday November 11 20219am SeattleRiti SarangiCombining X-ray Spectroscopy and DFT Methods to Connect Spectral Features to Electronic Structure of Bioinorganic Systems
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Thursday November 18 20219am Seattle
Christian Wittee Lopes
Tracking metallic species in molecular sieves by XAS