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X-WR-CALNAME:IXAS: The International X-ray Absorption Society
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X-WR-CALDESC:Events for IXAS: The International X-ray Absorption Society
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BEGIN:VEVENT
DTSTART;TZID=America/Los_Angeles:20200423T090000
DTEND;TZID=America/Los_Angeles:20200423T100000
DTSTAMP:20260416T071138
CREATED:20200512T033410Z
LAST-MODIFIED:20200512T035931Z
UID:327-1587632400-1587636000@xrayabsorption.org
SUMMARY:Joe Fowler: X-ray Fluorescence Line Metrology for the 21st Century
DESCRIPTION:Databases of x-ray fluorescence line energies such as those of Deslattes (2003) and Bearden (1967) are critical to the calibration of any analytical tools that identify elemental compositions by their x-ray “fingerprints.” To be useful\, such tables have to favor completeness over accuracy. Unfortunately\, a full 75% of the lines in the current NIST database (SRD-128) rely on measurements at least 50 years old\, coming from an age when the SI meter and the x-ray wavelength had never been tied together. Worse\, SRD-128 lacks all information about line shapes or any M lines whatsoever. At NIST\, we have begun a program to measure as many lines as possible with transition-edge sensor (TES) microcalorimeters\, starting with the hard x-ray L lines of certain lanthanide metals. As Kelsey Morgan described on March 30\, a TES combines advantages of solid-state detectors and diffractometers: it measures an enormous spectral region at once with resolving power of 1000 or higher. In tandem\, we have also rejuvenated the SI-traceable diffractometer of Deslattes’ team\, in order to expand the limited set of lines available for calibration of the TES spectrometer. \nhttps://arxiv.org/abs/1702.00507 and https://arxiv.org/abs/1511.03950
URL:https://xrayabsorption.org/events/journalclub-joe-fowler/
CATEGORIES:XAFS Journal Club
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/Los_Angeles:20200420T090000
DTEND;TZID=America/Los_Angeles:20200420T100000
DTSTAMP:20260416T071138
CREATED:20200512T033612Z
LAST-MODIFIED:20200512T035931Z
UID:329-1587373200-1587376800@xrayabsorption.org
SUMMARY:Rene Bes: Nuclear fuel study using XAS: benefits of HERFD for U valence states evaluation
DESCRIPTION:The safe use and disposal of UO2 based nuclear fuels relies on the stability of their material properties\, under extreme conditions of temperature and irradiation\, and with constantly evolving chemical composition. Among them\, the uranium valence state’s behavior is at the heart of safety assessment during the entire fuel lifecycle. First\, the oxidation from UO2 to UO3 induces for example considerable reorganization of the crystal structure and results in a volume expansion of about 36% when reaching the U3O8 intermediate state\, eventually leading to fuel cladding failure. Secondly\, the uranium valence state U6+ and to a lesser extent U5+ are known to have solubility several orders of magnitude higher than U4+\, which is a critical parameter during fuel final disposal\, the UO2 matrix very slow dissolution acting as the ultimate barrier of radioactivity release into the environment. X-ray absorption spectroscopy (XAS) is a key technique to assess U valence states in nuclear fuels thanks to its elemental sensitivity. However\, XAS applied to nuclear fuels suffers from the presence of almost all the periodic table in spent fuel\, from the high radioactive background limiting the number of available beamlines\, from the fact that transmission mode is often impossible to perform\, and from the large core-hole broadening effects. I will discuss how High Energy Resolution Fluorescence Detected XAS (HERFD-XAS) can help overcoming those drawbacks through a selection of a few recent examples\, and I will describe the main benefits of HERFD for U valence state evaluation. \nReferences:\nK. O. Kvashnina\, S. M. Butorin\, P. Martin\, and P. Glatzel\, Phys. Rev. Lett. 111 (2013) 253002 http://dx.doi.org/10.1103/PhysRevLett.111.253002 ;\nR. Bès\, M. Rivenet\, P.-L. Solari\, K. O. Kvashnina\, A. C. Scheinost\, and P. M. Martin\, Inorg. Chem. 55 (2016) 4260-4270 http://dx.doi.org/10.1021/acs.inorgchem.6b00014 ;\nG. Leinders\, R. Bès\, J. Pakarinen\, K. Kvashnina\, and M. Verwerft\, Inorg. Chem. 56 (2017) 6784−6787 http://dx.doi.org/10.1021/acs.inorgchem.7b01001;\nG. Leinders\, R. Bès\, K. Kvashnina\, and M. Verwerft\, Inorg. Chem. 59 (2020) 4576−4587 https://dx.doi.org/10.1021/acs.inorgchem.9b03702
URL:https://xrayabsorption.org/events/journalclub-rene-bes/
CATEGORIES:XAFS Journal Club
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/Los_Angeles:20200416T090000
DTEND;TZID=America/Los_Angeles:20200416T100000
DTSTAMP:20260416T071138
CREATED:20200512T033955Z
LAST-MODIFIED:20200512T035931Z
UID:332-1587027600-1587031200@xrayabsorption.org
SUMMARY:Yulia Pushkar:	X-ray Emission Spectroscopy at X-ray Free Electron Lasers: Limits to Observation of Unperturbed Electronic Structures
DESCRIPTION:Modern free electron lasers provide intense X-ray pulses with 10^12 photons within ~10-100 femtoseconds. Such pulses enable new experimental techniques and provide unique opportunities for investigation of electronic and nuclear dynamics on their intrinsic time-scales. Interaction of ultra-bright\, ultra-short X-ray pulses with matter can induce a multitude of nonlinear excitation processes which must be carefully considered when planning spectroscopic measurements and interpreting data recorded at XFELs. In most cases correct interpretation of the spectroscopic response and analysis of the electronic structure hinges on the assumption of single photon excitations. Here we attempted to answer the fundamental question on the limits to probing the ground (or native) electronic structure of a 3d transition metal ion at XEFL sources. Ions of the 3d transition metal\, e.g.\, Mn(II)\, in a lighter element (O\, C\, H) environment were used as a model system. X-ray emission spectroscopy recorded from Mn2+ at different pulse conditions demonstrate spectral changes as a function of increased pulse intensity and pulse duration. To explain these changes\, we develop a rate equation based on sequential ionization and relaxation events forming multiply ionized states during a single pulse which agree with observed spectroscopic trends. The percentage of Mn Kbeta emission recorded after the 1st\, 2nd and 3rd 1s ionization events is calculated from the developed rate equation model and validated by experimental measurements. A method for estimating shifts in atomic X-ray emission lines from sequential ionization during a single XFEL pulse is given. From our data we infer that\, in addition to multiple ionization\, the impact of electron cascades is more significant for longer pulses. We note that while use of shorter X-ray pulses will help to counteract additional effects of electron cascades it will not help to overcome the spectral shifts due to sequential ionization. Presented data and associated analysis will help with experimental designs at current and upcoming XFELs where even higher intensities and shorter pulses are expected. 3d elements have a variety of important applications such as in bio-inorganic catalysis\, chemical catalysis and energy storage / conversion making robust protocols for their XFEL analysis of general importance. \nhttp://dx.doi.org/10.1021/acs.jpclett.8b03595
URL:https://xrayabsorption.org/events/journalclub-yulia-pushkar/
CATEGORIES:XAFS Journal Club
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/Los_Angeles:20200413T090000
DTEND;TZID=America/Los_Angeles:20200413T100000
DTSTAMP:20260416T071138
CREATED:20200512T034144Z
LAST-MODIFIED:20200512T035931Z
UID:334-1586768400-1586772000@xrayabsorption.org
SUMMARY:Jacinto Sa:	Solving chemical mechanisms with X-ray spectroscopy
DESCRIPTION:As a scientist have been always fascinated with how chemical systems react and interact with the natural world. Spectroscopy is a great tool to look at systems in real-time and operation conditions. Hard X-ray photon-in photon-out spectroscopy offers great possibilities due to its chemical sensitivity and speciation as well as high penetration. In this webinar\, I will talk about two chemical processes and the developments in X-ray spectroscopy that made the studies possible. My studies have been made possible with the development of the dispersive von Hamos-type spectrometer (1)\, which enabled us to perform high-resolution studies on real systems due to its simple and versatile geometry. The first case study is called atomic telemetry\, a method that enables us to follow chemotherapy drugs action mechanism under physiological conditions. The methodology was validated with a known drug (cisplatin) but in this webinar\, I will present the findings from a drug (Pt-103) with an unknown action mechanism (2). The second case relates to the understanding of plasmonic materials hot carrier formation\, and their importance to solar applications. Using synchrotron radiation and HR-XAS we were able to demonstrate for the first time the formation of hot electrons (3). However\, to address their dynamics one needed to develop a way to perform RIXS measurements at the XFEL with the shortest and most intense X-ray pulses. I will show how we can do that (4) and what we plan to do with this methodology. \nReferences: (1 ) J. Szlachetko et al. Rev. Scie. Instrum. 2012\, 83\, 103105 https://doi.org/10.1063/1.4756691  (2 ) J. Czapla-Masztafiak et al. J. Phys. Chem. Lett. 2017\, 8\, 805-811 https://doi.org/10.1021/acs.jpclett.7b00070 (3) J. Sá\, et al. Energy Scie. Technol. 2013\, 6\, 3584-3588 https://doi.org/10.1039/C3EE42731E (4) Y. Kayser et al. Nat. Commun. 2019\, 10\, 4761 https://doi.org/10.1038/s41467-019-12717-1
URL:https://xrayabsorption.org/events/jacinto-sasolving-chemical-mechanisms-with-x-ray-spectroscopy/
CATEGORIES:XAFS Journal Club
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/Los_Angeles:20200409T090000
DTEND;TZID=America/Los_Angeles:20200409T100000
DTSTAMP:20260416T071138
CREATED:20200512T034432Z
LAST-MODIFIED:20200512T035932Z
UID:337-1586422800-1586426400@xrayabsorption.org
SUMMARY:Neil Hyatt: Multimodal microfocus XAS to understand and remediate DU munitions contamination
DESCRIPTION:The talk will show how multimodal microfocus X-ray spectroscopy has been applied to characterize depleted uranium particles from munitions testing to predict and understand their environmental behavior. A combination of spatially resolved XRD\, XRF and XAS techniques\, combined with laboratory SEM observations\, is shown to effectively differentiate DU particulate contamination in near surface and burial sites\, and provide evidence of particulate alteration. This knowledge was used to design and understanding more effective remediation measures for depleted uranium contamination\, with multimodal characterisation supporting process optimisation. \nReferences:\nCrean et al.\, Environ. Sci. Tech.\, 2014\, 48\, 1467; https://doi.org/10.1021/es403938d \nCrean et al.\, J. Haz. Mat.\, 2013\, 263\, 382. https://doi.org/10.1016/j.jhazmat.2013.08.013
URL:https://xrayabsorption.org/events/journalclub-neil-hyatt/
CATEGORIES:XAFS Journal Club
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/Los_Angeles:20200406T090000
DTEND;TZID=America/Los_Angeles:20200406T100000
DTSTAMP:20260416T071138
CREATED:20200512T034629Z
LAST-MODIFIED:20200512T035932Z
UID:339-1586163600-1586167200@xrayabsorption.org
SUMMARY:Steve Heald: Sector 25 at the APS-U: Two new beamlines for advanced spectroscopy
DESCRIPTION:As part of the Advanced Photon Source (APS) Multibend Achromat lattice upgrade two new beamlines for spectroscopy will be constructed on a canted undulator source at Sector 25. The programs at the 20-ID beamline at the APS need to move to sector 25 to make room for a planned long beamline. These will be combined with some other APS spectroscopy programs at sector 25 to use two new beamlines on a canted undulator. These two beamlines will service existing and upgraded endstations covering a variety of spectroscopy applications. There will be a microprobe branch that will provide sub-micron beams for fluorescence imaging\, and micro-XAFS. These can be combined with confocal optics for micron level depth sensitivity. This branch will also have a station for XAFS experiments requiring a high-brilliance high-flux beam such as doped thin films or ultra-dilute samples. The second Advanced Spectroscopy branch will provide beam to two inline hutches. The first will have stations for both an enhanced LERIX spectrometer for non-resonant inelastic scattering (x-ray Raman)\, and spectrometers for high resolution emission spectroscopy. The second hutch will provide space for experiments requiring extensive setup\, such as time-resolved pump-probe experiments. Both hutches will have a variety of focusing options providing beam sizes down to a few microns. To provide greater beam separation\, both lines will have side deflecting mirrors for harmonic rejection\, and focusing/collimation. The planned energy ranges are 4-32 keV for the microprobe branch\, and 4-40 keV for the Advanced Spectroscopy branch. The horizontal deflection mirrors allow use of small offset monochromators equipped with liquid nitrogen cooled Si (111) crystals for monochromatic beam\, and wide-bandpass multilayers providing higher flux for experiments that do not need high resolution such as imaging and non-resonant emission spectroscopy. The Advanced Spectroscopy branch will also have a secondary monochromator for experiments needing better resolution than provided by Si (111).
URL:https://xrayabsorption.org/events/journalclub-steve-heald/
CATEGORIES:XAFS Journal Club
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/Los_Angeles:20200402T090000
DTEND;TZID=America/Los_Angeles:20200402T100000
DTSTAMP:20260416T071138
CREATED:20200512T034838Z
LAST-MODIFIED:20200512T035932Z
UID:341-1585818000-1585821600@xrayabsorption.org
SUMMARY:Martin McBriarty: Top-Down Approaches to EXAFS Analysis
DESCRIPTION:EXAFS spectra are often modeled using a small number of virtual coordination shells which can vary in coordination number\, bond length\, and disorder. While this bottom-up approach is generally successful for single-phase samples\, it becomes intractable when the element of interest occupies multiple complex coordination states. Such cases may require a top-down approach\, in which the measured spectrum is fitted using models with fixed atom positions and disorder. Given reasonable starting assumptions\, such as ab initio molecular dynamics (AIMD) simulations of each possible component of the sample\, the actual coordination states can be identified and quantified. I will present two examples of top-down solutions to difficult EXAFS problems: (1) the mechanisms of uranium incorporation into iron (oxyhydr)oxide minerals\, and (2) the distribution of crystal phases in ferroelectric HfO2/ZrO2 nanostructures \nhttps://onlinelibrary.wiley.com/doi/full/10.1002/pssb.201900285 https://pubs.acs.org/doi/abs/10.1021/acs.est.8b00297
URL:https://xrayabsorption.org/events/journalclub-martin-mcbriarty/
CATEGORIES:XAFS Journal Club
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/Los_Angeles:20200330T090000
DTEND;TZID=America/Los_Angeles:20200330T100000
DTSTAMP:20260416T071138
CREATED:20200512T035015Z
LAST-MODIFIED:20200512T035932Z
UID:343-1585558800-1585562400@xrayabsorption.org
SUMMARY:Kelsey Morgan: Hot science with cool sensors
DESCRIPTION:The transition-edge sensor (TES) microcalorimeter uses the sharply temperature-dependent resistance of the superconducting transition to measure the energy of X-ray and gamma ray photons. A single TES is a broadband\, energy-dispersive area detector capable of eV-scale energy resolution with good quantum efficiency. With an array of hundreds or thousands of sensors\, a TES-based spectrometer can have orders of magnitude higher throughput than wavelength dispersive instruments. In this talk\, I will introduce the basic principles of TES operation\, and discuss how they are exploited to design sensors with resolving power R > 1000 at a wide range of photon energies\, from soft X-rays to gamma rays. This capability makes the TES a powerful tool for PFY-XAFS\, RIXS\, and time-resolved XES/XAS measurements\, particularly for weak sources or for highly dilute or radiation-sensitive samples. I will provide a brief overview of the TES spectrometers that are currently available to the X-ray science community\, and then highlight some exciting new instruments that are currently under development. \nhttps://physicstoday.scitation.org/doi/full/10.1063/PT.3.3995
URL:https://xrayabsorption.org/events/journalclub-kelsey-morgan/
CATEGORIES:XAFS Journal Club
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/Los_Angeles:20200326T090000
DTEND;TZID=America/Los_Angeles:20200326T100000
DTSTAMP:20260416T071138
CREATED:20200512T035155Z
LAST-MODIFIED:20200512T035932Z
UID:345-1585213200-1585216800@xrayabsorption.org
SUMMARY:Adam Hitchcock: Soft X-ray Spectromicroscopy in Scanning Transmission X-ray Microscopes
DESCRIPTION:Soft X-ray scanning transmission microscopy (STXM) is a powerful tool for nanoscale materials analysis\, with significant advantages over analytical electron microscopies for studies of radiation sensitive materials. Chemical species identified by near edge X-ray absorption fine structure (NEXAFS) spectra can be mapped quantitatively in 2D and in 3D. STXM instrumentation and methods will be described\, with emphasis on spectromicroscopy: chemical mapping by the analysis of images measured at many photon energies. Performance will be illustrated by recent studies of (i) cathodes of low temperature\, proton exchange membrane fuel cells (PEM-FC)\, which are under development for automotive applications\, and (ii) biomineralization of single domain\, single crystal nano-magnetite by magnetotactic bacteria. \nReferences: https://doi.org/10.1016/j.elspec.2015.05.013 and https://doi.org/10.1016/j.jpowsour.2018.01.074 and https://doi.org/10.1016/j.chemgeo.2019.119348
URL:https://xrayabsorption.org/events/journalclub-adam-hitchcock/
CATEGORIES:XAFS Journal Club
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/Los_Angeles:20200323T090000
DTEND;TZID=America/Los_Angeles:20200323T100000
DTSTAMP:20260416T071138
CREATED:20200512T035351Z
LAST-MODIFIED:20200512T035932Z
UID:347-1584954000-1584957600@xrayabsorption.org
SUMMARY:Evan Jahrman	Core-to-core X-ray Emission Spectroscopy: Pitfalls and Advantages for Lab-based and Synchrotron Users
DESCRIPTION:Core-to-core X-ray emission spectroscopy (CTC-XES) has not only provided key insights into atomic physics but is extremely well positioned to serve as a major analytical technique for several materials systems in the coming decades. Moreover\, CTC-XES frequently serves as an enabling phenomenon for more exotic varieties of synchrotron-based XAFS. I will cover several applications of CTC-XES and explain the origin and shape of commonly observed spectral features. I intend to make this talk both a pleasant refresher for seasoned X-ray physicists and useful to graduate students preparing to embark on their own materials characterization campaigns. \nReferences: https://doi.org/10.1103/PhysRevB.50.11347 and\nhttps://doi.org/10.1021/acs.analchem.8b00302
URL:https://xrayabsorption.org/events/journalclub-evan-jahrman/
CATEGORIES:XAFS Journal Club
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/Los_Angeles:20200319T090000
DTEND;TZID=America/Los_Angeles:20200319T100000
DTSTAMP:20260416T071138
CREATED:20200512T035516Z
LAST-MODIFIED:20200512T035557Z
UID:349-1584608400-1584612000@xrayabsorption.org
SUMMARY:Simo Huotari:	X-ray Raman spectroscopy: glimpse of the state of the art for samples in complex environments
DESCRIPTION:In this lecture I will continue where the previous lecture ends and talk about some examples of how XRS is used to study materials under high pressure and chemical reactions. \nReferences: https://www.nature.com/articles/nmat3031 and https://pubs.acs.org/doi/abs/10.1021/jp912208v
URL:https://xrayabsorption.org/events/journalclub-simo-huotari/
CATEGORIES:XAFS Journal Club
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/Los_Angeles:20200318T090000
DTEND;TZID=America/Los_Angeles:20200318T100000
DTSTAMP:20260416T071138
CREATED:20200512T035717Z
LAST-MODIFIED:20200512T035717Z
UID:351-1584522000-1584525600@xrayabsorption.org
SUMMARY:Jerry Seidler: What is X-ray Raman Scattering\, and What Did Raman Have to Do With It?
DESCRIPTION:X-ray Raman Scattering (XRS\, often also called nonresonant inelastic x-ray scattering)\, is a hard x-ray alternative to soft x-ray NEXAFS. I’ll review the basic physics\, including the role of momentum transfer to tune selection rules. And I’ll explain Raman’s involvement\, or lack thereof. \nReferences:\nhttps://journals.aps.org/prb/abstract/10.1103/PhysRevB.74.214117  and https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.105.053202
URL:https://xrayabsorption.org/events/journalclub-jerry-seidler_mar2020/
CATEGORIES:XAFS Journal Club
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