Energy-dispersive X-ray spectroscopy (EDS) is a technique used for elemental analysis of materials. When a sample is exposed to an energy source like an electron beam, core shell electrons are ejected from atoms in the sample. Higher energy electrons fill these holes and release X-rays with energies characteristic of the atom. An EDS system detects these X-rays to identify elements present and generate a spectrum. The spectrum shows peaks corresponding to elemental composition. EDS allows quick, non-destructive chemical analysis of complex samples down to the micron scale.

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ENERGY – DISPERSIVE X – RAY
SPECTROSCOPY (EDS)
BY:-
Anmar Talal
Supervisor
Assist. Prof. Dr. Jabbar Gattmah
University of Diyala
College Of Engineering
Materials
Engineering Department

2. Energy Dispersive Spectrometry
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Function
Introduction
working of EDS
Principle
Basic components
Results

3. Energy Dispersive Spectrometry:
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Energy-dispersive X-ray spectroscopy (EDS, EDX, EDXS or XEDS), sometimes called
energy dispersive X-ray analysis (EDXA or EDAX) or energy dispersive X-ray microanalysis
(EDXMA)
Function:
EDS is a 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.
EDS can be used to find the chemical composition of materials down to a spot size of
a few microns, and to create element composition maps over a much broader raster
area.

4. Energy Dispersive Spectrometry:
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Introduction:
Energy Dispersive Spectrometry (EDS) was first introduced in the late
1960s.
Before that time, the wavelength-dispersive spectrometer (WDS) was used
for x-ray characterization.
In the late 1960s, Fitzgerald, Keil, and Heinrich first used the solid state
detector as an electron beam micro analyzer.

5. Diagram:
The basic design of an energy dispersive spectrometer is shown in Figure.
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6. Basic Principle:
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Principle of EDS.

7. Basic Principle:
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The incident beam may excite an electron in an inner shell, ejecting it from the shell
while creating an electron hole where the electron was.
An electron from an outer, higher-energy shell then fills the hole, and the difference
in energy between the higher-energy shell and the lower energy shell may be
released in the form of an X-ray.
The number and energy of the X-rays emitted from a specimen can be measured by
an energy-dispersive spectrometer. the energy of the X-rays are characteristic of the
difference in energy between the two shells, and of the atomic structure of the
element from which they were emitted, this allows the elemental composition of the
specimen to be measured.

8. Working:
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The detector generates a charge pulse proportional to the X-ray energy
This pulse is first converted to a voltage.
 Then the signal is amplified through a field effect transistor (FET)
,isolated from other pulses , further amplified ,then identified electronically
as resulting from an X-ray of specific energy
Finally, a digitized signal is stored in a channel assigned to that energy in the
MCA(Multi Channel Analyzer).

9. Basic Components:
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Detector
• Window
• Cryostat
Pulse
Processor
• Amplifier
Multi-
Chanel
Analyzer
• MCA

10. Energy-dispersive X-ray spectroscopy
• Energy-dispersive X-ray spectroscopy (EDS, also abbreviated EDX or XEDS) is an
analytical technique that enables the chemical characterization/elemental analysis of
materials. A sample excited by an energy source (such as the electron beam of an electron
microscope) dissipates some of the absorbed energy by ejecting a core-shell electron.
• A higher energy outer-shell electron then proceeds to fill its place, releasing the difference in
energy as an X-ray that has a characteristic spectrum based on its atom of origin.
• This allows for the compositional analysis of a given sample volume that has been excited
by the energy source. The position of the peaks in the spectrum identifies the element,
whereas the intensity of the signal corresponds to the concentration of the element.
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11. EDS materials analysis
• Sensitive to low concentrations—minimum detection limits below 0.1% in
the best cases
• Affords a high degree of relative precision—typically 2–4%
• Non-destructive in most situations
• Usually requires minimal sample preparation effort and time
• Delivers complete analyses of complex samples quickly, often in under a
minute
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13. Detector:
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Window:
The window is made up of Beryllium.
The window provides a barrier to maintain vacuum within the detector
whilst being as transparent as possible to low energy X-rays.

14. Cryostat:
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- The charge signals generated by the detector are small and can only be
separated from the electronic noise of the detector if the noise is reduced
by cooling the crystal and FET.
The Field Effect Transistor is the first stage of the amplification process that
measures the charge liberated in the crystal by an incident X-ray and
converts it to a voltage output.
- The natural width (FWHM) of an X-ray peak is on the order of 2-10 eV .

15. Pulse Processor:
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The signal (voltage step) from the preamplifier is transformed into a voltage pulse
that is suitable for the multi channel analyzer.
The time over which the waveform is averaged is called the process time (Tp).
Tp is under control of the operator. The longer the Tp, the lower the noise but
more time is spent measuring each X- ray, and the fewer events that can be
measured.
If noise is minimized, the resolution of the peak displayed in the spectrum is
improved, and it becomes easier to separate or resolve, from another peak that is
close in energy.

16. Graph:
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17. Multi-Chanel Analyzer (MCA)
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The MCA takes the data from the pulse processor and displays it as a
histogram of intensity (number of counts) vs voltage.
The voltage range (for ex., 20 keV) displayed on the x- axis is divided into a
number (1024, 2048 etc.) of channels each corresponding to a given energy
range (for example, 5,280 eV –5,300 eV).
The MCA takes the peak height of each voltage pulse, converts it into a
digital value, and puts it into the appropriate channel.
Thus a count is registered at that energy level.

18. Output forms of EDS:
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Spectrum
• Spectrum: a plot of the number of
X-rays detected versus their
energies.
• The Characteristic X-rays allow the
elements present in the sample to
be identified.

19. Conti…
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Map:
Map: an image showing how the
concentration of one element varies
over an area of a sample. In this
example, red colors indicate higher
concentrations and blue colors reflect
lower concentrations.

20. References
1. Corbari, L; et al. (2008). "Iron oxide deposits associated with the ectosymbiotic
bacteria in the hydrothermal vent shrimp Rimicaris exoculata" (PDF).
Biogeosciences. 5 (5): 1295–1310. doi:10.5194/bg-5-1295-2008. Archived from
the original (PDF
2. Joseph Goldstein (2003). Scanning Electron Microscopy and X-Ray
Microanalysis. Springer. ISBN 978-0-306-47292-3.
3. Jenkins, R. A.; De Vries, J. L. (1982). Practical X-Ray Spectrometry. Springer.
ISBN 978-1-468-46282-1.
4. Kosasih, Felix Utama; Cacovich, Stefania; Divitini, Giorgio; Ducati, Caterina
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