xrd

1. CRESCENT SCHOOL OF PHARMACY
X-RAY DIFFRACTION
Dr. Y. Ismail
Associate Professor
Crescent School Of Pharmacy
presented by
S.BASITH REHMAN
RRN No: 220582601003
M.Pharm 1st year (Dept. Of pharmaceutics)

2. Contents
 INTRODUCTION
 WHY X RAY AND WHY XRD
 PRINCIPLE
 BRAGG’S LAW
 INSTRUMENTATION
 POWDER X-RAY DIFFRACTION METHOD
 ROTATING CRYSTAL METHOD
 APPLICATIONS OF X-RAY DIFFRACTION
 ADVANTAGES
 REFERENCES

3. X-Ray Diffraction
Introduction
 X-ray diffraction is used to obtain structural information about
crystalline solids.
 Useful in biochemistry to solve the 3D structures of complex
biomolecules.
 Bridge the gaps between physics, chemistry, and biology.
X-ray diffraction is important for:
 Solid-state physics
 Biophysics
 Medical physics
 Chemistry and Biochemistry

4. What is X-ray?
Beams of electromagnetic radiation
smaller wavelength than visible light,
higher energy
more penetrative

5. Why XRD?
 Measure the average spacings between layers or rows of
atoms
 Determine the orientation of a single crystal or grain
 Find the crystal structure of an unknown material
 Measure the size, shape and internal stress of small crystalline
regions

6. PRINCIPLE
In 1912, discovered that crystalline substances act as three-
dimensional diffraction gratings for X-ray wavelengths similar to
the spacing
X-ray diffraction is now a common technique for the study of
crystal structures and atomic spacing.
 X-ray diffraction is based on interference of monochromatic X-
rays and a crystalline sample.
Bragg's Law (nλ=2d sin θ). This law relates the wavelength of
electromagnetic radiation to the diffraction angle and the lattice
spacing in a crystalline sample.

8. INSTRUMENTATION
 X-ray diffractometers consist of three basic elements: an X-ray tube, a
sample holder, and an X-ray detector.
 X-rays are generated in a cathode ray tube by heating a filament to produce
electrons, accelerating the electrons toward a target by applying a voltage,
and bombarding the target material with electrons.
 When electrons have sufficient energy to dislodge inner shell electrons of
the target material, characteristic X-ray spectra are produced.
 Filtering, by foils or crystal mono chrometers, is required to produce
monochromatic X-rays needed for diffraction.
 These X-rays are directed onto the sample.
 As the sample and detector are rotated, X-rays is recorded.
 A detector records and processes this X-ray signal and converts the signal to
a count rate which is then output to a device such as a printer or computer
monitor.

10. POWDER X-RAY DIFFRACTION METHOD
In powder method, the crystal sample need not be taken in large quantity
but as little as 1mg of the material is sufficient for the study.
A is a source of X-rays which can be made monochromatic by a filter.
Allow the X-ray beam to fall on the powdered specimen P through the
slits S1 & S2. The function of these slits is to get a narrow pencil of
X-rays

11. ROTATING CRYSTAL METHOD

12. Applications of X-Ray Diffraction
 To Find structure to determine function of proteins
 Distinguish between different crystal structures with
identical compositions
 Study crystal deformation and properties
 Study of rapid biological and chemical processes

14. References
Wilson, K. S. (2018). An Introduction to X‐Ray Crystallography.
ELS, 1–16. https://doi.org/10.1002/9780470015902.a0025432.
Text book of instrumental methods of chemical analysis by
chatwal pg -294 to 319.