X-ray Generation by Scattering of Incident Electrons
- Practical Electron Microscopy and Database -
- An Online Book -

http://www.globalsino.com/EM/  



 

This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.

 

=================================================================================

In EM measurements, after a core electron has been emitted from an ionized atom, this atom quickly decays from its excited state to its ground state and thus may produce a characteristic X-ray (“radiative”) or an Auger electron (“nonradiative”). Therefore, these processes of inner-shell ionization loss are different aspects of the same phenomenon. Both processes compete for the decay.

Table 3815 shows that electrons interact with 1 electron, many electrons, 1 nucleus, and many nuclei in solids.

Table 3815. Effects of interactions of electrons in solids.
  Interaction with electron(s) Interaction with nucleus/nuclei
  1 electron Many electrons 1 nucleus Many nuclei
Scattering type Inelastic Inelastic Quasi-elastic Elastic Inelastic
Scattering effect Electron Compton effect; electron excitation (from 50 eV to a few keV: EDS and EELS) Plasmon excitation (< 50 eV, ~100 nm TEM specimen); Cerenkov effect Rutherford scattering; phonon scattering (< 1 eV, heat) Bragg scattering Bremsstrahlung

In EDS measurements, the path of X-ray absorption mainly depends on two factors:
         i) The depth of x-ray generation in the specimen.
         ii) The take-off angle.

In addition to the specimen itself, the X-ray generation process is also affected by the probe size, current, and convergence angle. Fortunately, elemental concentration quantification can be done with reasonable accuracy by comparing the peak intensities with k-factors in EDS spectra.

 

=================================================================================

The book author (Yougui Liao) welcomes your comments, suggestions, and corrections, please click here for submission. If you let book author know once you have cited this book, the brief information of your publication will appear on the “Times Cited” page.