XAFS Journal Club

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 […]

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 […]

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 […]

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 […]

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, […]

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 […]

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 […]

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 […]

The conservation of marine archaeological wood is complicated by the presence of iron and sulfur. The sulfur originates from sulfate ions in seawater being transformed by sulfur reducing bacteria, and iron from dissolved fixture and artefacts. Incorporated in to the wood as reduced sulfur/iron compounds, such as pyrite, they can become problematic during the drying […]

Using High-Energy-Resolution-Fluorescence-Detection (HERFD), one can sharpen the pre-edge structures revealing their multiplet nature. In ionic systems, they can be calculated from the transition from the 3dN ground state to the 1s13dN+1 final state, where covalent systems need the inclusion of charge transfer effects. The main edge is usually interpreted from the calculation of the transitions […]

We will look at how electrochemically active materials such as batteries can be studied in a concerted way by tuning to relevant resonant x-ray absorption at both the soft and the hard x-ray energy regimes. We will specifically examine the role of oxygen in the charge compensation of LiMO2 delafossite compounds, that serve as cathodes […]

I will present details of the TES Beamline at the National Synchrotron Light Source II, covering its design, commissioning, and early results. Its scientific mission includes static and in-situ/operando XRF imaging and spatially resolved (microbeam) XAS -- in the tender energy range -- for characterization of complex heterogeneous, structured and dynamic natural or engineered materials […]