X-ray Absorption Spectroscopy (XAS)

X-ray Absorption Spectroscopy (XAS) is a powerful technique used to analyze the chemical state and local electronic structure of elements across a wide range of research fields. In this method, the transmission or fluorescence of X-rays is measured while gradually increasing the X-ray energy in small increments near the element’s absorption edge. The absorption edge corresponds to the specific energy required to eject an electron from an inner shell of the target element (for example, iron—Fe). Subtle variations in X-ray absorption around this edge reveal detailed information about the electronic state and local chemical environment of the atom.

X-ray Absorption Spectroscopy (XAS) is a powerful analytical technique used to study the chemical state and local atomic structure of specific elements within a material. It finds applications across diverse research fields such as materials science, chemistry, physics, biology, and environmental science.

The technique works by measuring the absorption of X-rays as their energy is gradually increased across the absorption edge of the element of interest (for example, iron – Fe). The absorption edge corresponds to the specific X-ray energy required to eject a core electron from one of the atom’s inner electron shells.

By analyzing how X-rays are absorbed just below and above this edge, researchers can obtain detailed information about:

• Oxidation states and electronic configuration of the absorbing atom

• Local coordination environment (types, numbers, and distances of neighboring atoms)

• Chemical bonding and structural distortions

These fine variations in absorption, collectively known as X-ray Absorption Fine Structure (XAFS), are divided into two main regions:

• XANES (X-ray Absorption Near Edge Structure): Provides information on oxidation state and local geometry.

• EXAFS (Extended X-ray Absorption Fine Structure): Reveals interatomic distances and coordination numbers.