QuantumLeap-XAS

Chemical speciation and electronic structure with
X-ray Absorption Spectroscopy (XAS)

X-ray absorption spectroscopy (XAS) is a powerful chemical analysis technique used for research in a broad range of applications, including:

  • Catalysts: chemical states of oxides, nitrides, and carbides being explored as catalysts

  • Batteries/fuel cells/solar cells: oxidation state of transition metals (e.g. in lithium ion batteries) as a function of charge and discharge cycles

  • Nanoparticles and nanomaterials: structural analysis, coordination number, disorder, geometry, reactivity

The QuantumLeap is the first laboratory XAS offering synchrotron-like performance.

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What is XAS? 

X-ray absorption spectroscopy involves measuring the transmission of x-rays as a function of increasing x-ray energy in small steps at energies close to the absorption edge (binding energy) of an element of interest, such as iron (Fe). Such measurements yield critical insight on chemical states, such as oxidation states, and electronic structure, such as bond lengths and electron geometry surrounding the atom.

 
 The two regimes of XAS: XANES (structures nearest to the edge) and EXAFS (typically includes structures around 1 keV above the absorption edge)

The two regimes of XAS: XANES (structures nearest to the edge) and EXAFS (typically includes structures around 1 keV above the absorption edge)

 

XAS is comprised of two regimes:

  1. X-ray absorption near edge structure (XANES/NEXAFS) region: Comprising x-ray energies nearest to the absorption edge (approximately 100 eV around the edge), this region exhibits sharp resonance peaks and more related to local atomic state (such as chemical state).

  2. Extended fine structure (EXAFS) are features that appear after the XANES region and up to 1000 eV or greater than the absorption edge. These features appear as gentle oscillations in the measured signal, and is caused by the multiple scattering of the ejected electron by surrounding atoms. Information in this region can be used to infer neighboring atom information, including bond lengths and chemical coordination environments.

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QuantumLeap Capabilities 

The QuantumLeap XAS system provides: high resolution (sub-eV) XANES and high throughput (within seconds) EXAFS. A demonstration of the system’s powerful capabilities can be seen below for Fe chemical state analysis, with acquisitions performed at 0.2 eV energy resolution. Results match synchrotron performance.

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QuantumLeap Interest

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