1. A.Solairajan,
1st year,
M.pharm(analysis).

2. Introduction
What is X-Ray?
 Basic principle
Instrumentation
 X Ray diffraction methods
 Applications.

3.  X-Rays are electromagnetic radiation with
wavelengths in the range 0.1 - 100 Å (0.01-10nm)
 X Rays used in diffraction experiments have
typical wavelengths of 0.5 - 1.8 Å
 X-rays were discovered by Wilhelm Roentgen
who called them X-rays and it also called as
Roentgen rays.
 X-ray diffraction was discovered by Max von
Laue in 1912.

5.  In an atom, the electrons
are arranged in layers or
shells, like
• K-shell
• L-shell
• M-shell
• N-shell

6.  When the atom is bombarded with an electron,
eject one of the electron from the inner shell.
 The electrons migrate from the outer shell to the
inner shell to fill the gap with higher energy.
 A quantum of radiation (X-rays)is emitted
corresponding to this transition , time scale is
approximately 10-12
-10-4
sec.
 Emitted radiation is called X-rays.

7. Inner orbit
Outer orbit
Emitted
radiation as
X-rays

10. X-rays are obtained in three ways.
 By bombardment of metal target with a
beam of high energy electrons.
 By exposure of a substance to a primary
beam of X-rays in order to generate a
secondary beam of X-ray fluorescence.
 By use of radioactive source decay process
results in X-ray emission.

13. There are four methods available.
 X-ray absorption methods
 X-ray Emission methods
 X-ray fluorescence methods
 X-ray diffraction methods.

14.  X-Ray absorption methods:-
A beam of X-rays is allowed to pass through
the sample and fraction of X-ray photons absorbed
is considered to be a measure of the concentration
of the absorbing substance.
 X-Ray emission methods:-
X-ray are obtained by employment of
radioactive source whose decay process results in
emission.

15.  X-ray fluorescence:-
In these methods, X-rays are generated within
the sample and by measuring the wavelength and
intensity of the generated X-rays, one can perform
qualitative and quantitative analysis.
 X-ray diffraction:-
These methods are based on the scattering of
x-ray by crystals. This method is used to identify
the crystal structures of various solid compounds.

16. A beam of X-ray is passed to the sample
X-ray photons absorbed by the substance.
Measuring the concentration of absorbing substance.
Applications:-
Elemental analysis such as barium and iodine in
the body

17. Beam of X-ray fall on sample
Emits secondary X-ray
Fluorescent X-ray
Intensity of X-ray provides
how much is present
Applications:-
Elemental analysis.

18. X-ray tube
Collimator
Monochromator
• Filter
• Crystal monochromator
Detectors

19. X-ray tube:-
High velocity of electrons bombarded on metal
target, X-rays are produced.
Collimator:-
Close metal plates separated by small gap.
Use is to produce narrow beam.
Monochromator:-
Absorbs the undesirable radiations and allows
required wavelength to pass.
Filter -E.g. Zirconium
Crystal -E.g. Sodium chloride, Lithium fluoride

20. Detectors:-
Photographic methods
Counter methods
Types:-
• Geiger-muller counter
• proportional counter
• Scintillation counter
• Solid state semiconductor counter
• Semiconductor

21. When X-rays interact with a solid material, the
scattered beams can add together in a few
directions and yield diffraction.

24.  X-ray diffraction is based on constructive
interference of monochromatic x-rays and a
crystalline sample.
 These x-rays are generated by a cathode ray tube,
filtered to produce monochromatic radiation
,collimated to concentrate and directed towards
the sample.
 The interaction of incident rays with the sample
produces constructive interference when
conditions satisfy Bragg’s law.

25. The relationship describing the angle at which a
beam of X-rays of a particular wavelength diffracts
from a crystalline surface was discovered by
William Bragg and Lawrence Bragg and is known
as Bragg’s law.

26. Bragg diffraction
For constructive
interference,
2(d sin ) = n 
}d

 
d
d sin d sin 
}
}

27. X-ray diffraction method is generally used for
investigation on the internal structure.
 Laue photographic method
 Bragg X-ray spectrometer method
 Rotating crystal method
 Powder method

28. This method is divided into two types.
 Transmission method
 Back Reflection method.

29. Transmission method:-
A beam of X-ray is passed through the crystal,
after passing through the crystal, X-rays are
diffracted and recorded on a photographic plate.

30. Back reflection method:-
This method provides similar
information as the transmission method.

31.  Using the Laue's photograph, Bragg analysed the
structures of crystals of sodium chloride, Kcl.
 Bragg devised a spectrometer to measure the
intensity of X-ray beam.
 The spectra obtained in this way can be employed
for crystallographic analyses.
 This is based on the Bragg’s equation:
nλ = 2dsinϴ

35.  A beam of X-ray beam is fall on to the powedered
specimen through slits.
 The sharp lines to be obtained on the photographic
film which is surrounding the powder crystal in the
form of circular arc.
 Powder diffraction patterns are typically plotted as
the intensity of the diffracted X-rays vs. the angle 2θ.
 Peaks will appear in the diffraction pattern at 2θ
values when constructive interference is at a
maximum, when Bragg’s Law is satisfied.
n λ = 2 d sin θ

38.  Identification of single phase materials-Minerals, chemical
compounds,ceramics.
 Identification of multiple phases in microcrystalline
mixtures(rocks).
 Determination of crystallite size and shape.
 Crystallographic structural analysis and unit cell calculation for
crystalline materials.
 Particle size determination-Spot counting methods,
-Broadening of diffraction lines

39. Instrumental methods of chemical analysis
by Gurudeep R. Chatwal.
 Wikipedia.org.