1. SUBMITTED BY:
Nayeema Khowser Shaik
M.Pharmacy Ist year
2020MPH40A029
UNDER THE GUIDANCE OF:
Dr. A. Sreedevi
M.Pharm., Ph.D.
Department of Pharmaceutics

2. TABLE OF CONTENTS 2
Department of Pharmaceutics, SPMVV
01
08
07
06
05
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04
03
02
Concept
Properties
Principle
Instrumentation
Production of X- Rays
Physics of X- Ray Production
X- Ray Diffraction Methods
Bragg’s Law
References

3. 3
CONCEPT
Department of Pharmaceutics, SPMVV
 X- Rays were discovered by Wilhelm Roentgen, so x-rays are also called
Roentgen rays.
 X-ray diffraction in crystals was discovered by Max von Laue. The wavelength
range is 10-7 to about 10-15 m.
 The penetrating power of x-rays depends on energy-
i. Hard x-rays: High frequency & More energy
ii. Soft x-rays: Less penetrating & Low energy
 X-rays are short wave length electromagnetic radiations produced by the
deceleration of high energy electrons or by electronic transitions of electrons
in the inner orbital of atoms.
 X-ray region- 0.1-100 A˚
 Analytical purpose- 0.7-2 A˚

4. Department of Pharmaceutics, SPMVV
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 A variety of X- Ray techniques and methods are in
use.
I. X- Ray Absorption Methods
II. X- Ray Diffraction Methods
III. X- Ray Fluorescence Methods
 The process of producing X- Rays may be visualised in
terms of Bohr’s Theory of atomic structure.
 Through X- Ray diffraction we can identify the crystal
structures of various solid compounds and identify a
compound from its structure. Arrangement of
molecules in a structure can also be determined.
 X- Ray crystallography is a powerful technique for
visualising the structure of a protein. It is used for
identifying the atomic and molecular structure of a
crystal.

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Department of Pharmaceutics, SPMVV
PROPERTIES
 Highly penetrating invisible rays
 Liberate minute amounts of heat on passing through matter
 Not deflected by electric and magnetic fields
 Poly energetic, having widespread energies and wavelengths
 Cause ionization (adding or removing electrons in atoms and molecules)
 Transmitted by (pass through) healthy body tissue
 Affect photographic film in the same way as visible light (turning it black)
 Absorbed (stopped) by metal and bone
 Cause photoelectric emission
 Produced when a beam of high-energy electrons strike a metal target
 Ionize gases indirectly by ability to remove orbital electrons from atom

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PRINCIPLE
Department of Pharmaceutics, SPMVV
 X-ray diffraction is based on constructive interference of
monochromatic x-rays and a crystalline sample.
 The interaction of incident rays with the sample produces
constructive interference when conditions satisfy Bragg’s law.
 X- Ray diffraction by crystal is a reflection of the periodicity of the
crystal architecture, so that imperfection in the crystal lattice
usually results in poor diffraction properties.
 The planes in the crystal lattice can be considered as a source of
diffraction and are designated by a set of three numbers called the
Miller indices (hkl).
nλ = 2d sinθ

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INSTRUMENTATION
Department of Pharmaceutics, SPMVV

8. 8
PRODUCTION OF X- RAYS
Department of Pharmaceutics, SPMVV
 X- Rays are generated when high velocity of electrons impinge on a metal target.
 1% of total energy of the electron beam is converted into X –radiation.
 Coolidge tube is a typical X- ray tube.
 Cathode of Tungsten metal is heated by a battery to
emit thermionic electrons. This beam of electrons
constitutes the cathode ray stream.
 If the positive voltage in the form of an anode
having a target is kept near these electrons, the
electrons are accelerated towards the target.
 On striking the target, the electrons transfer their energy to its metallic surface which
then gives off X-ray radiations.

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Department of Pharmaceutics, SPMVV
 Choice of target material-
i. Sample
ii. Atomic number greater than the elements
iii. Energy of X- rays emitted should be greater than that
required to excite the elements being irradiated
 Source of electrical energy-
i. Filament heating voltage (10V) and current (10A)
ii. Accelerating voltage (30-150 kV) between anode and cathode
 Solution when target gets hot-
i. Cooling the tube with water
ii. Rotating the target at high speed, to reduce the production of localised heating
Advantage Disadvantage
Permits the production of X- ray of intensity
much greater than that obtainable from
stationary target.
Lack of focussing of the electrons so that whole
surface becomes a source of X- rays.

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Department of Pharmaceutics, SPMVV
PHYSICS OF X- RAY PRODUCTION
Characteristic radiation
 This energy emission happens when a fast-
moving electron collides with a K-shell electron, the electron in
the K-shell is ejected (provided the energy of the incident
electron is greater than the binding energy of K-shell electron)
leaving behind a 'hole’.
 An outer shell electron fills this hole (from the L-shell, M-shell,
etc. ) with an emission of a single x-ray photon, with an energy
level equivalent to the energy level difference between the
outer and inner shell electron involved in the transition.
 It is represented by a line spectrum.
 Characteristic radiation never exists in isolation and the line spectra is usually superimposed on the
continuous spectra of bremsstrahlung radiation.

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Department of Pharmaceutics, SPMVV
Bremsstrahlung x-rays
 Bremsstrahlung radiation is the radiation
given off by a charged particle (most often
an electron) due to its acceleration caused by
an electric field of another charged particle
(most often a proton or an atomic nucleus).
 “Braking radiation” - electrons are “braked”
 The incident electrons are free, meaning they’re not bound to an atom or ion, both before
and after the braking.
 It can have any energy ranging from zero to the maximum KE of the bombarding electrons
(i.e., 0 to Emax), depending on how much the electrons are influenced by the electric field,
therefore forming a continuous spectrum. The 'peak' of the spectrum typically occurs at
approximately one-third of Emax.
Intensity= Z² z / m

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X- RAY DIFFRACTION METHODS
Department of Pharmaceutics, SPMVV
 Used for investigating the internal structures and crystal structures of various solid compounds.
1. Laue’s photographic method
 Transmission method
 Back reflection method
2. Bragg’s X- ray spectrometer
3. Rotating crystal method
4. Powder method

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Department of Pharmaceutics, SPMVV
Transmission Laue Method
 In the transmission Laue method, the film is placed
behind the crystal to record beams which are
transmitted through the crystal.
 The film intersects the cone, with the diffraction
spots generally lying on an ellipse.
 Most suitable for the investigation of preferred orientation sheet particularly confined to
lower diffraction angles.
 Used in determination of symmetry of single crystals.
 Leonhardt chart for transmission patterns.

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Department of Pharmaceutics, SPMVV
Back- Reflection Laue Method
 In the back-reflection method, the film is
placed between the x-ray source and the
crystal. The beams which are diffracted in a
backward direction are recorded.
 The film intersects the cone, with the
diffraction spots generally lying on a
hyperbola.
 It is the only method for the study of large and thick specimens.
 Greninger chart is used for back-reflection patterns.
 Disadvantage- Big crystals are required

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Department of Pharmaceutics, SPMVV
Bragg’s X- Ray Spectrometer Method
 Laue-beam of x-ray-crystal-emitted x-ray obtained on photographic plate-using
photograph-brag analysed structures of crystals of NaCl, KCl, and ZnS- Bragg’s equation.
 From the pattern we can deduce different distances between planes-angle between
planes in each of three dimensions.

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Department of Pharmaceutics, SPMVV
 Crystal is mounted such that ѳ=0° and ionization
chamber is adjusted to receive x-rays.
 The angle through which the chamber is moved is
twice the angle through which the crystal is rotated.
 X- rays falls on crystal surface. The crystal is rotated
and x-rays are made to reflect from various lattice
planes.
 By applying Bragg’s equation ratio of lattice spacing
for various groups of planes can be obtained.
 Experimentally observed ratio’s are compared with
the calculated ratio’s ,particular structure may be
identified.
 Peaks corresponds to Bragg’s reflection.

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Department of Pharmaceutics, SPMVV
BRAGG’S LAW
 The law explains the relationship between an x-ray light shooting into and its reflection off
from crystal surface.
 When a crystal is bombarded with X-rays of a fixed
wavelength and at certain incident angles, intense
reflected X-rays are produced when the wavelengths
of the scattered X-rays interfere constructively.
 In order for the waves to interfere constructively, the differences in the travel path must be
equal to integer multiples of the wavelength. When this constructive interference occurs, a
diffracted beam of X-rays will leave the crystal at an angle equal to that of the incident beam.
nλ = 2d sinθ

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REFERENCES
Department of Pharmaceutics, SPMVV
1. Instrumental methods of chemical analysis ,G. R. Chatwal, Sham K.
Anand, Himalaya publications
2. Instrumental methods of chemical analysis ,B.K.sharma,17th edition
1997-1998,GOEL publishing
3. https://radiopaedia.org/articles/characteristic-radiation
4. https://astronomy.swin.edu.au/cosmos/b/bremsstrahlung+radiation
5. https://serc.carleton.edu/research_education/geochemsheets/Bragg
sLaw.html
6. https://chem.libretexts.org/Bookshelves/Analytical_Chemistry
7. Animations- https://www.presentermedia.com/

19. THANK YOU !