Dated: 14/09/2023
Characterization of Engineering Materials
Assignment no 2
Submitted by:
Name: Muhammad Musa Raja
Reg no: 2021-MM-11
Department: Metallurgical and Materials Engineering
Submitted to:
Dr. Asif Rafiq
University of Engineering
And
Technology
Dated: 14/09/2023
Use of X-Rays in
XRF, EDX & WDX
X-ray Fluorescence (XRF):
XRF (X-ray fluorescence) is a non-destructive analytical technique used to determine the
elemental composition of materials. XRF analyzers determine the chemistry of a sample by
measuring the fluorescent (or secondary) X-ray emitted from a sample when it is excited by a
primary X-ray source.
Use of X-ray & Process:

A solid or a liquid sample is irradiated with high energy X-rays from a controlled Xray tube.

When an atom in the sample is struck with an X-ray of sufficient energy (greater than
the atom’s K or L shell binding energy), an electron from one of the atom’s inner orbital
shells is dislodged.

The atom regains stability, filling the vacancy left in the inner orbital shell with an
electron from one of the atom’s higher energy orbital shells.

The electron drops to the lower energy state by releasing a fluorescent X-ray. The
energy of this X-ray is equal to the specific difference in energy between two quantum
states of the electron. The measurement of this energy is the basis of XRF analysis.
Fig1: XRF process
Dated: 14/09/2023
Energy Dispersive X-ray Spectroscopy (EDX):
Energy-dispersive X-ray spectroscopy (also known as EDS, EDX, or EDXA) is a powerful
technique that enables the user to analyze the elemental composition of a desired sample.
Use of X-ray & Process:
The major operating principle that allows EDS to function is the capacity of high energy
electromagnetic radiation (X-rays) to eject 'core' electrons (electrons that are not in the outermost
shell) from an atom. This principle is known as Moseley's Law, which determined that there was
a direct correlation between the frequency of light released and the atomic number of the atom.
Removing these electrons from the system will leave behind a hole that a higher energy electron
can fill in, and it will release energy as it relaxes. The energy released during this relaxation process
is unique to each element on the periodic table, and as such bombarding a sample with X-rays can
be used to identify what elements are present, as well as what proportion they are present in.
Fig2: EDX process
How is Data Collected?
EDX functions with a series of three major parts: an emitter, a collector, and an analyzer. These
parts are additionally typically equipped on an electron microscope such as SEM or TEM. The
combination of these three pieces enables analysis of both how many X-rays are released, as well
as what their energy is (in comparison to the energy of the initial X-rays that were emitted). The
EDX data is presented as a graph with KeV on the x-axis and peak intensity on the y-axis.
Dated: 14/09/2023
Wavelength Dispersive X-ray Spectroscopy:
Wavelength dispersive x-ray fluorescence spectroscopy (WDXRF or WDX) is a non-contact, nondestructive technique used to measure elemental composition, elemental concentration per unit
area, and film thickness. Due to its acute element sensitivity, it is particularly useful for identifying
trace elements.
Use of X-rays & Process:
In a WDX measurement, the sample is irradiated with high energy x-rays. This irradiation
stimulates the emission of characteristic x-rays associated with elements present in the material.
WDXRF spectrometers use Bragg diffraction from crystals within the instrument to produce
wavelength-separated peaks, each associated with a specific element. This yields semiquantitative, and quantitative (if calibrated), information about the elements present in the sample
matrix and their atomic ratios.
Unlike the related Energy-Dispersive X-ray Fluorescence (EDXRF or EDX) variant, WDX has
excellent light element detection capability.
Fig3: graph between energy and intensity
Advantages of WDX:

Able to detect all elements present in a sample with atomic number > 4 (Be).

Highest element sensitivity among XRF techniques, enables identification of trace
elements.

Rapid, straightforward measurement with semi-quantitative concentration measurements.
Dated: 14/09/2023
Reference:
1. XRF. (2020). Thermo Fisher Scientific. https://www.thermofisher.com/blog/ask-ascientist/what-is-xrf-x-ray-fluorescence-and-how-does-it-work/
2. EDS. (2018-2019). LibreTexts Chemistry.
https://chem.libretexts.org/Courses/Franklin_and_Marshall_College/Introduction_to_Mat
erials_Characterization__CHM_412_Collaborative_Text/Spectroscopy/EnergyDispersive_X-ray_Spectroscopy_(EDS)
3. WDXRF. Covalent Metrology. https://covalentmetrology.com/techniques/wavelengthdispersive-x-ray-fluorescence-spectroscopy-wdxrf/