Question

Explain the characteristics of x ray absorption spectra

Answer 1

X-rayabsorption spectroscopy(XAS) is a widely used technique for determining the local geometric and/or electronic structure of matter. The experiment is usually performed atsynchrotron radiationsources, which provide intense and tunableX-raybeams. Samples can be in the gas-phase, solution, or condensed matter (i.e. solids).XAS data is obtained by tuning thephotonenergy using a crystalline monochromator to a range wherecore electronscan be excited (0.1–100 keV, 16–16,022 aJ, photon energy). The edges are, in part, named by which core electron is excited: theprincipal quantum numbersn = 1, 2, and 3, correspond to the K-, L-, and M-edges, respectively. For instance, excitation of a 1s electron occurs at theK-edge, while excitation of a 2s or 2p electron occurs at anL-edge(Figure 1) [1].