Energy-dispersive X-ray spectroscopy (EDS, EDX, EDXS or XEDS), sometimes called energy dispersive X-ray analysis (EDXA) or energy dispersive X-ray microanalysis (EDXMA), is an analytical technique used for the elemental analysis or chemical characterization of a sample. It relies on an interaction of some source of X-ray excitation and a sample. Its characterization capabilities are due in large part to the fundamental principle that each element has a unique atomic structure allowing a unique set of peaks on its electromagnetic emission spectrum^[2] (which is the main principle of spectroscopy). The peak positions are predicted by the Moseley’s law with accuracy much better than experimental resolution of a typical EDX instrument.

Energy Dispersive X-Ray Spectroscopy (EDS or EDX) is a chemical microanalysis technique used in conjunction with scanning electron microscopy (SEM). The EDS technique detects x-rays emitted from the sample during bombardment by an electron beam to characterize the elemental composition of the analyzed volume. Features or phases as small as 1 µm or less can be analyzed.

When a sample is bombarded by a SEM’s electron beam (top image), inner shell electrons may be ejected from atoms at the sample’s surface (center image). The energy of the SEM electron (e^–) beam must be greater than the energy with which the inner shell electron is bound to the nucleus of the atom. When an inner orbital electron is ejected from an atom, an electron from a higher energy level orbital will be transferred to the lower energy level orbital. During this transition a photon may be emitted from the atom. This fluorescent light (Kα) is the characteristic X-ray of the element (bottom image). The energy of the emitted photon will be equal to the difference in energies between the two orbitals occupied by the electron making the transition. Because the energy difference between two specific orbital shells, for a given element, is always the same (i.e. characteristic of that particular element), the photon emitted when an electron moves between these two levels will always have the same energy. Therefore, by determining the energy (keV) of the X-ray light (photon) emitted by a particular element, it is possible to determine the identity of that element.

For a particular energy (keV) of fluorescent light emitted by an element, the number of photons per unit time (generally referred to as peak intensity or count rate) is related to the amount of that analyte in a sample. The counting rates for all detectable elements within a sample are usually calculated by counting, for a set amount of time, the number of photons that are detected for the various analytes’ characteristic X-ray energy lines. Therefore, by determining the energy of the X-ray peaks in a sample’s spectrum, and by calculating the count rate of the various elemental peaks, it is possible to qualitatively establish the elemental composition and to quantitatively measure the concentration of those elements.

The EDS X-ray sensor measures the relative abundance of emitted X-rays versus their energy. Today sensors are typically Peltier-cooled, solid-state silicon drift detector (SDD) devices. When an incident X-ray strikes the detector, it creates a charge pulse that is proportional to the energy of the x-ray. The charge pulse is converted to a voltage pulse (which remains proportional to the x-ray energy) by a charge-sensitive pre-amplifier. The signal is then sent to a multichannel analyzer where the pulses are sorted by voltage. The energy, as determined from the voltage measurement, for each incident X-ray is sent to a computer for display and further data evaluation. The spectrum of x-ray energy versus counts is evaluated to determine the elemental composition of the sampled volume.

Electron Probe Micro Analysis Course Materials

• Sample Syllabus

Lecture Notes

• Title Page
• Chapter 1 Introduction
• Chapter 2 Specimen Interactions
• Chapter 3 Nature of X-rays
• Chapter 4 Electron Optics
• Chapter 5 Wavelength Dispersive Spectrometry
• Chapter 6 Energy Dispersive Spectrometry
• Chapter 7 Statistics
• Chapter 8 Mapping and Imaging
• Chapter 9 Matrix Corrections

Power Point Files (By Lecture Number)

1. Introduction to the EPMA/SEM laboratory: An introduction to the technique followed by a short tour of the facilities and including discussion of lecture notes, suggested reading materials, grading methods, exams and current research projects followed by a short history of the instrument and related techniques.
2. Electron beam instrumentation and electron solid interactions: A brief description of the major system components for both the electron microprobe and scanning electron microscope followed by an introduction to elastic and inelastic scattering of electrons and associated principles. (chapters 1 and 2)
3. X-ray productions: The generation and emission of characteristic and continuum x-rays and their absorption and fluorescence interactions within the sample. (chapter 3)
4. Electron Beam Columns: Formation, alignment, and choices for parameterization with regards to application and specimen interaction. (chapter 4)
5. Lab: Demonstration of electron beam parameters and sample interactions.
6. WDS (wavelength dispersive spectrometery): A description of the Bragg spectrometer and associated principles. (chapter 5)
7. Lab: Demonstration of wavelength dispersive spectrometry technique and analysis.
8. EDS (energy dispersive spectrometery): Spectral analysis using the EDS detector. (ch. 6)
9. Lab: Demonstration of energy dispersive spectrometry technique and analysis.
10. Statistics: The essential key to scientific analysis. (chapter 7)
11. Lab: Examples of the application of statistical calculations to quantitative analysis.
12. Quantitative matrix corrections: What goes on in the computer? An introduction to the corrections being applied to the intensity data in order to obtain elemental concentrations. Take home mid-term exam given out at the end of the lecture and due next class meeting. (chapter 9). See also this PPT on standard accuracy by John Fournelle.
13. Digital Imaging (Lecture and Lab): Imaging and mapping: An overview of electron and x-ray imaging and mapping techniques and the principles involved along with a demonstration of the analog and digital mapping capabilities on the electron microprobe.
14. Volz, Heather M., et al. Development of a macroscopic quantitative x-ray fluorescence capability to study heterogeneities in cast uranium alloys. No. LA-UR-10-02375; LA-UR-10-2375. Los Alamos National Lab.(LANL), Los Alamos, NM (United States), 2010.
15. Scipioni, Larry, Lewis Stern, and John Notte. “Applications of the helium ion microscope.” Microscopy Today 15.6 (2007): 12-15.
16. Bode, Michael. “The Case For Digital Imaging.” Microscopy Today 7.8 (1999): 23-25.
17. Atomic spectrometry update: review of advances in the analysis of metals, chemicals and functional materials. Carter, Simon; Fisher, Andy; Garcia, Raquel; Gibson, Bridget; Marshall, John; Whiteside, Ian. JAAS (Journal of Analytical Atomic Spectrometry). Nov2016, Vol. 31 Issue 11, p2114-2164. 51p. DOI: 10.1039/c6ja90044e.

• Feng, L., V. D. Saveliev, M. Takahashi, C. R. Tull, S. Barkan, E. V. Damron, S. Kosuge, R. D. Lamb, K. C. Witherspoon, and Per O. Sjoman. “An Improved Large Area Silicon Drift Detector EDS System for Low Energy X-ray Detection and Fast Spectrum Imaging.” Microscopy and Microanalysis 15, no. S2 (2009): 174-175.
• Cross, Brian John, and K. C. Witherspoon. “Integrated XRF in the SEM.” Microscopy and Microanalysis 10.S02 (2004): 104.
• Newbury*, Dale E., and Nicholas WM Ritchie. “Is scanning electron microscopy/energy dispersive X‐ray spectrometry (SEM/EDS) quantitative?” Scanning 35.3 (2013): 141-168.
• Martiny, Andrea, et al. “SEM/EDS analysis and characterization of gunshot residues from Brazilian lead-free ammunition.” Forensic Science International 177.1 (2008): e9-e17.
• Newbury, Dale E., and Nicholas WM Ritchie. “Elemental mapping of microstructures by scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDS): extraordinary advances with the silicon drift detector (SDD).” Journal of Analytical Atomic Spectrometry 28.7 (2013): 973-988.
• Gazulla, M. F., et al. “Nitrogen determination by SEM‐EDS and elemental analysis.” X‐Ray Spectrometry 42.5 (2013): 394-401.
• Akkaş, Efe, et al. “Application of decision tree algorithm for classification and identification of natural minerals using SEM–EDS.” Computers & Geosciences 80 (2015): 38-48.
• Wilkinson, Kai, et al. “New tabletop SEM-EDS-based approach for cost-efficient monitoring of airborne particulate matter.” Environmental Pollution 159.1 (2011): 311-318.
• Figueiredo, Elin, et al. “Inclusions and metal composition of ancient copper‐based artefacts: a diachronic view by micro‐EDXRF and SEM‐EDS.” X‐Ray Spectrometry 40.5 (2011): 325-332.
• Ramirez-Leal, Roberto, Maryanna Valle-Martinez, and Martin Cruz-Campas. “Chemical and morphological study of PM10 analysed by SEM-EDS.” Open Journal of Air Pollution 3.04 (2014): 121.
• Goldstein, J. I., Newbury, D. E., Michael, J. R., Ritchie, N. W., Scott, J. H. J., & Joy, D. C. (2017). Scanning electron microscopy and X-ray microanalysis. Springer.
• https://en.wikipedia.org/wiki/Electron_microscope
• https://en.wikipedia.org/wiki/Scanning_electron_microscope
• https://en.wikipedia.org/wiki/Energy-dispersive_X-ray_spectroscopy

• • EDS
  • EDX
  • EDXS
  • XEDS
  • EDXA
  • EDXMA
  • SEM/EDS
  • SEM/EDX
  • SEM/EDXS
  • SEM/XEDS
  • SEM/EDXA
  • SEM/EDXMA
  • Energy dispersive X-ray analysis
  • Energy-dispersive spectroscopy
  • Energy-dispersive X-ray spectroscopy
  • Energy dispersive X-ray microanalysis
  • X-ray microanalysis
  • Microanalysis
  • Micro-analysis
  • X-ray micro-analysis
  • SEM X-ray microanalysis
  • SEM micro-analysis
  • SEM X-ray micro-analysis
  • SEM microanalysis
  • SEM-EDS
  • SEM-EDX
  • SEM-EDXS
  • SEM-XEDS
  • SEM-EDXA
  • SEM-EDXMA
  • Energy dispersive X-ray analysis
  • Electron microscopy
  • Scanning electron microscopy