Analysis of selenium-containing amino acids by X-ray absorption spectroscopy (XAS) (CAT#: STEM-ST-0271-WXH)

X-ray spectroscopy works on the principle of the excitation of core electrons that are orbiting in the lower shell(s). As the electron absorbs x-rays, it becomes excited and jumps to a higher level. The X-ray region used ranges from 1 to 100 nm. When x-rays interact with electrons it excites electrons to the higher levels. Energy absorbed by the electrons has a characteristic value for each element one can distinguish with the X-ray absorption spectrum.
X-ray absorption spectroscopy (XAS) is the measurement of transitions from core electronic states of the metal to the excited electronic states (LUMO) and the continuum; the former is known as X-ray absorption near-edge structure (XANES), and the latter as extended X-ray absorption fine structure (EXAFS) which studies the fine structure in the absorption at energies greater than the threshold for electron release. These two methods give complementary structural information, the XANES spectra reporting electronic structure and symmetry of the metal site, and the EXAFS reporting numbers, types, and distances to ligands and neighboring atoms from the absorbing element

X-ray absorption spectroscopy (XAS) is a widely used technique for determining the local geometric and/or electronic structure of matter.

• X-ray generating equipment (X-ray tube)
• Collimators
• Monochromators
• X-ray detectors