XRF (X-ray fluorescence) HosseinBondori1993@Gmail.com

1. XRF (X-ray fluorescence)
By: Hossein Bandori
Kharazmi University
Department of Geology

2. X-rays make up X-radiation, a form of electromagnetic radiation.
Most X-rays have a wavelength ranging from 0.01 to 10 nanometers,
corresponding to frequencies in the range 30 petahertz to 30 exahertz
(3×1016 Hz to 3×1019 Hz) and energies in the range 100 eV to 100 keV. X-
ray wavelengths are shorter than those of UV rays and typically longer
than those of gamma rays. In many languages, X-radiation is referred
to with terms meaning Röntgen radiation, after the German scientist
Wilhelm Röntgen, who usually is credited as its discoverer, and who
had named it X-radiation to signify an unknown type of radiation.
Spelling of X-ray(s) in the English language includes the variants x-
ray(s), xray(s), and X ray(s).

3. X-rays are part of the electromagnetic spectrum, with wavelengths
shorter than visible light. Different applications use different parts of
the X-ray spectrum.

4. Application of X-Ray

5. X-ray fluorescence
X-ray fluorescence (XRF) is the emission of
characteristic "secondary" (or fluorescent) X-rays
from a material that has been excited by bombarding
with high-energy X-rays or gamma rays. The
phenomenon is widely used for elemental analysis
and chemical analysis, particularly in the
investigation of metals, glass, ceramics and building
materials, and for research in geochemistry, forensic
science, archaeology and art objects such as
paintings[2] and murals.

6. A Philips PW1606 X-ray fluorescence
spectrometer with automated sample feed in
a cement plant quality control laboratory

7. • In 1925 X-rays were used for the first time to excite a sample, but the
technique was only made practical in 1940 and the first commercial
XRF spectrometers were produced in 1950.
• These were based on wavelength dispersive x-ray fluorescence
(WDXRF) and measured the wavelength of an element, one element
at a time.
• In the 1960’s energy dispersive x-ray fluorescence (EDXRF)
spectrometers began to rival WDXRF.
• Since the 1960’s XRF spectrometers have progressed greatly and XRF
spectrometers was even included on the Apollo 15 and 16 missions.

8. • Some of the applications of XRF include: research and development,
soil surveys, mining, cement production, ceramic and glass
manufacturing, quality control (metallurgy), environmental studies,
petroleum industry and field analysis in geological and
environmental studies.

12. FUNDAMENTAL PRICIPLES OF XRF
XRF works on methods involving interactions between electron beams
and x-rays with samples.
• Made possible by the behavior of atoms when they interact with
radiation.
• When materials are excited with high-energy, short wavelength
radiation (e.g., X-rays), they can become ionized.
• If the energy of the radiation is sufficient to dislodge a tightly- held
inner electron, the atom becomes unstable and an outer electron
replaces the missing inner electron.
• When this happens, energy is released due to the decreased binding
energy of the inner electron orbital compared with an outer one.

13. PRINCIPLES CONT’D
• The emitted radiation is of lower energy than the primary incident X-
rays and is termed fluorescent radiation.
• Because the energy of the emitted photon is characteristic of a
transition between specific electron orbitals in a particular element, the
resulting fluorescent X-rays can be used to detect the abundances of
elements that are present in the sample.

14. Excitation of the sample Spectrometer Secondary X-Rays or X- Ray
Fluorescence which is characteristic for the elemental composition of
the sample Sample

15. An Incoming X-Ray photon strikes
an electron, the electron breaks free
and leaves the atom.
Principle of the excitation by X-Rays

16. Principle of the excitation by X-Rays
• This leaves a void that must be filled by an electron from an outer
shell.
• The excess energy from the new electron is released (fluorescence)
in the form of an x-ray photon. X-Ray Photon X-Ray Fluorescence

17. excitation by X-Rays

18. Excitation and Interactions between shells Layer K Layer L
Layer N Layer M

19. Excitation and Interactions between shells Layer K Layer L Layer N
Layer M

20. XRF - HOW IT WORKS?
• An XRF spectrometer works because if a sample is illuminated by an
intense X-ray beam, known as the incident beam, some of the energy is
scattered, but some is also absorbed within the sample in a manner that
depends on its chemistry.

21. • The incident X-ray beam is typically produced from a Rh target,
although W, Mo, Cr and others can also be used, depending on the
application.
XRF - HOW IT WORKS?

22. XRF - HOW IT WORKS?
• When x-ray hits sample, the sample emits x-rays along a spectrum of
wavelengths characteristic of the type of atoms present.
• Flow counters measure long wavelength(>0.15nm) x-rays typical of
elements lighter than zinc.
• The scintillation detector is commonly used to analyze shorter
wavelengths in the X-ray spectrum(K spectra of element from Nb to I; L
spectra of Th and U).

23. • If a sample has many elements present, the use of a Wavelength
Dispersive Spectrometer allows the separation of a complex emitted X-
ray spectrum into characteristic wavelengths for each element present.
• Various types of detectors used to measure intensity of emitted
radiation. • Examples of detectors used include the flow counter and
the scintillation detector.
XRF - HOW IT WORKS?

24. • The intensity of the energy measured by these detectors is
proportional to the abundance of the element in the sample.
• The exact value for each element is derived from standards from prior
analyses from other techniques.
XRF - HOW IT WORKS?

25. BOX DIAGRAM OF XRF INSTRUMENT

26. • Minimal or no sample preparation
• Non-destructive analysis
• Na11 to U92 analysis, ppm to high % concentration
range
BENEFITS OF XRF ANALYSIS

27. • No wet chemistry – no acids, no reagents
• Analysis of solids, liquids, powders, films, granules
etc.
• Rapid analysis – results in minutes
BENEFITS OF XRF ANALYSIS

28. • Qualitative, semi-quantitative, to full quantitative
analysis
• For routine quality control analysis instrument can
be ‘used by anyone’
BENEFITS OF XRF ANALYSIS

29. APPLICATIONS
X-Ray fluorescence is used in a wide range of
applications, including
• research in igneous, sedimentary, and metamorphic
petrology
• soil surveys
• mining (e.g., measuring the grade of ore)

30. • cement production
• ceramic and glass manufacturing
• metallurgy (e.g., quality control)
• environmental studies (e.g., analyses of particulate
matter on air filters)
APPLICATIONS

31. APPLICATIONS CONT’D
• petroleum industry (e.g., sulfur content of crude oils
and petroleum products)
• field analysis in geological and environmental
studies (using portable, hand-held XRF
spectrometers) X-ray fluorescence is limited to
analysis of
• relatively large samples, typically > 1 gram

32. • materials that can be prepared in powder form and
effectively homogenized
• materials for which compositionally similar, well-
characterized standards are available
• materials containing high abundances of elements
for which absorption and fluorescence effects are
reasonably well understood
APPLICATIONS CONT’D

33. STRENGTHS & LIMITATIONS OF XRF
Strengths X-Ray fluorescence is particularly well-
suited for investigations that involve:
• bulk chemical analyses of major elements (Si, Ti, Al,
Fe, Mn, Mg, Ca, Na, K, P) in rock and sediment
• bulk chemical analyses of trace elements (>1 ppm;
Ba, Ce, Co, Cr, Cu, Ga, La, Nb, Ni, Rb, Sc, Sr, Rh, U, V,
Y, Zr, Zn) in rock and sediment

34. STRENGTHS & LIMITATIONS OF XRF
Strengths X-Ray fluorescence is particularly well-
suited for investigations that involve:
• bulk chemical analyses of major elements (Si, Ti, Al,
Fe, Mn, Mg, Ca, Na, K, P) in rock and sediment

35. • bulk chemical analyses of trace elements (>1 ppm;
Ba, Ce, Co, Cr, Cu, Ga, La, Nb, Ni, Rb, Sc, Sr, Rh, U, V,
Y, Zr, Zn) in rock and sediment
STRENGTHS & LIMITATIONS OF XRF

36. LIMITATIONS
In theory the XRF has the ability to detect X-ray
emission from virtually all elements, depending on
the wavelength and intensity of incident x-rays.
However...
• In practice, most commercially available
instruments are very limited in their ability to
precisely and accurately measure the abundances of
elements with Z<11 in most natural earth materials.

37. • XRF analyses cannot distinguish variations among
isotopes of an element, so these analyses are
routinely done with other instruments.
• XRF analyses cannot distinguish ions of the same
element in different valence states, so these analyses
of rocks and minerals are done with techniques such
as wet chemical analysis or Mossbauer spectroscopy.
LIMITATIONS

38. No mater how the secondary X-ray radiation (X-Ray
fluorescence) is produced in XRF machines there are
TWO WAYS to detect this radiation:
XRF detection system

39. ◦ Wavelength Dispersive System (WDS) and
◦ Energy Dispersive System (EDS).
XRF detection system

40. • A wavelength dispersive detection system
physically separates the X-Rays according to their
wavelengths.
• The x-rays are directed to a crystal, which diffracts
(according to Bragg´s Law) the X-Rays in different
directions according to their wavelengths
(energies).
WDS

41. XRF: A Powerful Analysis Tool

42. • EDS is an analytical technique used for the
elemental analysis or chemical characterization of a
sample.
• The secondary x-rays (XRF) are directed to a
detector.
EDS

43. • A detector is used to convert X-ray energy into
voltage signals; this information is sent to a pulse
processor, which measures the energy of the signals
and passes them onto an analyzer.
• The analyzer converts the analog into a digital signal
which is proportional to the energy of the incoming
pulse.
EDS

44. • Received pulses are actually amplified and
converted into digital signals.
• They are sorted by energy with help of multi-
channel analyzer (energy is characteristic for each
element) and frequency of appearance (characteristic
for concentration) and sent to data display and
analysis.
EDS

45. • The most common detector now is Si(Li) detector
cooled to cryogenic temperatures with liquid
nitrogen.
EDS

46. EDS
ED-XRF

47. EDS
SEM-EDX

48. Specifically designed for the
rigorous demands of
nondestructive elemental
analysis in the field.
HANDHELD XRF

49. • The XRF method of characterization provides a fast
and reliable way of acquiring information on;
• the elementary composition
• and chemical state.
CONCLUSION

52. THE
End