What is the energy range for NEXAFS?

NEXAFS, or Near Edge X-ray Absorption Fine Structure, refers to a technique that provides information about the electronic structure of materials through their absorption of X-rays. In this context, Ei represents the binding energy of core electrons in the material, which is a critical point where NEXAFS spectra are measured.

The correct choice highlights that the energy range extends from the initial energy level Ei up to Ei + 50 eV. This range is crucial as it encompasses the energies just above the core electron binding energies, where absorption features indicative of unoccupied molecular orbitals can be observed. This provides valuable insights into the local electronic environment around the absorbing atom and the chemical state of the material.

Understanding NEXAFS is essential in various fields, including surface chemistry, materials science, and biophysics, as it helps elucidate the structural and electronic properties of complex materials. The specific range of Ei to Ei + 50 eV allows researchers to focus on the fine structure of the edges associated with core-level transitions, which are pivotal in characterizing materials at the atomic level.