XAS

Battery-material characterisation usually falls into three layers. Diffraction and electron microscopy read structure and morphology. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) read chemical state. In-situ diffraction and absorption read the charge–discharge process. In an all-solid-state cell the interface reactions often sit inside the sample, so that part leans on synchrotron X-ray diffraction (SXRD) and X-ray absorption spectroscopy (XAS), which can penetrate the cell. ...

The near-edge structure (XANES) of an X-ray absorption spectrum can be used to discuss the local chemical environment of the absorbing atom. The thirteen questions below are grouped as structure and speciation, quantitative analysis, and how a spectrum changes. The thirteen questions Approach What is observed Example or question Coordination edge and near-edge shape separate valence, coordination number, or geometry Crystallinity spectral shape crystalline versus amorphous $\mathrm{SiO...

Synchrotron radiation (SR) and X-ray absorption spectroscopy (XAS) are often mentioned together, but they are not the same object. A synchrotron is a light source. XAS is an experiment that uses X-rays interacting with matter to analyse a sample. The synchrotron: a source of tunable X-raysSynchrotron radiation is the electromagnetic radiation emitted along the tangent when a fast charged particle is deflected in a magnetic field. In 1947, researchers saw the intense radiation produced when hi...

SXAS stands for Soft X-ray Absorption Spectroscopy. It belongs to the wider family of XAS, with the photon energy kept between roughly 50 eV and 2 keV. That window happens to cover: the K-edges of carbon, nitrogen, oxygen and fluorine (a 1s electron is excited); the L-edges of 3d transition metals (2p → 3d); some alkali and alkaline-earth edges. In other words, it is good at light elements and 3d metals — exactly the actors in battery materials, catalysts, polymers and biomolecules. The ab...