X-ray crystallography is a scientific technique used to determine the atomic and molecular structure of crystals. When x-rays strike a crystal, the beam diffracts into specific directions. This diffraction pattern can be analyzed to reveal the nature and structure of the crystal lattice. Bragg's law defines the relationship between x-ray wavelength, diffraction angle, and interplanar spacing and is used to calculate crystal structures from diffraction data. X-ray crystallography is widely used to determine protein structures and has applications in pharmaceuticals, materials science, and other fields.

1. STRUCTURAL ANALYSIS BY X-RAY
CRYSTALLOGRAPHY
By
SIJINU MATHEW
Physical Science
Roll no 13
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2. ELECTRO MAGNETIC SPECTRUM
 Electro magnetic spectrum is the entire range of electro
magnetic waves from lower to higher frequency. It
contain various types of radiations.
 gamma rays, x-rays, UV-Visible, IR, Micro waves and
radio waves.
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3. ELECTRO MAGNETIC SPECTRUM
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4. X-RAYS
 X-rays have the short wavelengths to see the atoms and
molecular structure of molecules.
 Wavelength range is 1-10 Å
 Discovered by Wilhelm Rontgen in 1895.
 It can be generated by reducing the speed of electrons.
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5. X-ray Crystallography
 It is a scientific method of determining the precise
arrangements of atoms in a crystal where beams of x-ray
strikes a crystal and causes the beam of light to diffract
into specific directions.
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6. Contd........
 This method is widely used to obtain high resolution
protein structural information.
 This technique relies the dual nature of x-rays to discover
information about structure of crystalline materials.
 The pattern produced by the diffraction of x-rays through
the closely spaced lattice of atoms in a crystal is
recorded and analysed to reveal the nature of that lattice.
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7. Contd....
 The sample that is in crystalline form is bombarded
with beam of x-rays , then most of the x-ray pass
straight through the crystal some are diffracted by it.
 The resulting pattern recorded by a detector .
 Pattern is the three dimensional structure of sample
 This method can give detailed atomic structure such as
about ligands, inhibitors, ions, and other molecules.
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8. Bragg’s Law
 It is a fundamental law and valid for monochromatic x-
rays only and it is used to calculate interplanar spacing
using x-ray diffraction spectra
 It defines the spacing(d) of atomic planes and incident
angle(Ө) at which x-rays of a particular wavelength will
reflect in phase.
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nλ = 2d sinθ
 The Bragg’s equation is,
nλ=2d sinθ

10. Single X-ray Crystallography
 It is the oldest and more precise model
 A beam of x-rays strikes a single crystal, producing
scattered beams.
 It has three steps,
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11. Instrumentation of Single X-ray
Crystallography
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12. Nature of the Crystal
 The crystal should be large , pure in composition and
regular in structure, with no significant internal
imperfections such as crack or twinning.
 The crystal placed in an intense beam of x-rays , usually
single wavelength producing regular pattern of
reflections.
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13. Contd......
 When the crystal is rotated that time reflection will
change and intensity will be recorded.
 These data are combined computationally with
complementary chemical information to produce and
refine a model of the arrangement of atoms with in the
crystal.
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14. Applications
 Determination of unit cell, bond-lengths, bond-angles
 Variations in crystal lattice
 With specialized chambers, structures of high pressure
and/or temperature phases can be determined
 Powder patterns can also be derived from single-crystals
by use of specialized cameras (Gandalf) applications.
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15. Limitations
 The unit cell is larger and more complex.
 The atomic level picture provided by x-ray
crystallography become less well resolved.
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16. TYPES OF X-RAY
CRYSTALLOGRAPHY
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Contd……
 X-ray generated in the tube T are passed through a slit,
so as to obtained a narrow beam which is then allowed to
strike single crystal which is mounted on the turn table.
 The crystal is rotated gradually by means of the turn table
as to increase the glancing angle.

19. Contd…….
 The intensities of the reflected rays are measured on a
recording device. The process is carried out for each
plane of the crystal till the angles for reflection θ give the
maximum value.
 The lowest angle at which the maximum reflection occurs
corresponds to n= 1. this is first order reflection and so
on.
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20. POWDER METHOD – DEBYE - SCHERRER
METHOD
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21. Contd….
 Used for the crystal with simple structure
 Powder contain small crystal that are oriented in all
directions .
 As a result x-rays are scattered from all sets of planes.
 Scattered rays are detected by using an x-ray sensitive
film.
 The finely powdered substance is kept in the form of a
cylinder inside a thin glass tube.
 Narrow beam of x-rays is allowed to fall on the powder.21

22.  The diffracted x-rays strike a strip of photographic film
arranged in the form of a cylindrical arc.
 In this method rotation is not needed because powder
sample contains micro crystals arranged in all possible
orientations.
 A large number of them will have their lattice planes in
corrected positions for maximum x-ray reflection to
occur.
 We get lighted areas in the form of arcs of lines at
different distances from the incident beam.
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23. Advantages
 Non-destructive nature, high sensitivity,
 Easy sample preparation,
 System is user friendly, operational procedure is
convenient, fast , effective resolution.
 Low maintenance cost, proper automation, easy data
interpretation that could be used for both qualitative and
quantitative analysis.
Disadvantage
 Use of harmful radiations.
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24. Applications
 Pharmaceutical industry
 Forensic studies
 In glass industry
 Crystalline study
 Nano and material science
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25. Factors Affecting X-ray Crystallography
 Purity of sample
 Concentration
 pH of solution
 Temperature
 Time
 Volume of crystallisation
 Pressure
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26. Advantages and Disadvantages
Advantages
 X-rays are the least expensive, most convenient and
widely used to determine crystal structures.
 X-rays are not absorbed very much by air, so the sample
need not be in an evacuated chamber.
Disadvantages
 X-rays do not interact very strongly with higher elements.
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27. Applications
 Distinguishing between crystalline & amorphous
materials.
 Determination of the structure of crystalline materials.
 Determination of electron distribution within the atoms &
throughout the unit cell.
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28.  Determination of the orientation of single crystals.
 Determination of the texture of polygrained materials.
 Measurement of strain and small grain size………
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29. Medical Applications
 In diagnosis & treatment
 Tuberculosis& emphysema
 Dentists
 CT or CAT(computerized axial tomography)
 X-ray therapy
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30. CONCLUSION
The advent of x-ray diffraction in the early 20th century
transformed crystallography from an area of scientific
inquiry largely limited to physics, mineralogy, and
mathematics to a highly interdisciplinary field which now
includes nearly all life and physical sciences as well as
material science and engineering.
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31. Reference
 https://en.wikipedia.org/wiki/X-ray crystallography
 www.academia.edu/7587033/x-ray crystallography and
its applications
 www.amicsonline.org
 http://xos.com
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