This document discusses electron diffraction and neutron diffraction techniques. Electron diffraction works by firing electrons at a crystal sample and observing the interference pattern of diffracted electrons. This allows determining atomic structure. Neutron diffraction also determines atomic structure by firing neutrons at samples and observing diffraction patterns. Key advantages of neutron diffraction are its ability to locate light atoms and detect isotopes via nuclear scattering, and reveal magnetic structure via magnetic scattering. Both techniques provide structural information at the atomic scale but neutron diffraction can analyze bulk properties and magnetic structures.

1. Electron Diffraction And
Neutron Diffraction
By
P.DEEPIKA
I M.Sc., CHEMISTRY
THIAGARAJAR COLLEGE
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2. CONTENTS
• INTRODUCTION
• PRINCIPLE
• INSTRUMENTATION
• WORKING
• APPLICATION
• ADVANTAGES
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3. When collimated beam of electron waves strikes pair of parallel
lattice planes in a crystal,each atom act as a scattering centre
and emits secondary waves All of the secondary waves
interfere with each other to produce diffracted beam
• An interaction between a wave of any kind
and an object of any kind
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4. TYPES OF DIFFRACTION
 X-RAY DIFFRACTION
 ELECTRON DIFFRACTION
 NEUTRON DIFFRACTION
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5. BASIC PRINCIPLE
Bragg’s law of diffraction:
When bragg’s law is satisfied, reflected beams are in phase and interfere
constructively to produce diffraction patterns
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6.  As Louis De-broglie predicted that wave properties should
also be associated with moving electrons and hence the
wavelength associated with the electrons are given by
ƛ=
ℎ
𝑚𝑣
 v depends on potential difference(p.d)
 For 10 to 10,000 volts ƛ varies between 3.89 to 0.12Ǻ hence
such electrons act as X-Ray towards crystal. 10,000 to 40,000
volts applied to get high speed electrons to be used in
diffraction
How X-ray Differs From Electron
Waves?
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7. INSTRUMENTATION
• It consists mainly of electron gun target and
luminescent screen
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9. WORKING
 It involves generation of electrons by a hot filament,
made accelerated by applying p.d of about 40,000
volts, passage of electrons passing through the sample
 As a result it get diffracted and the effect is seen on
the fluorescent screen in the form of concentric rings
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10. ELECTRON DIFFRACTION PATTERNS
Mosaic single crystal Plate like texture Polycrystal
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11. GRAPHICAL PLOT
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12. GRAPHICAL PLOT
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13. APPLICATIONS
• It is used to investigate the nature of solid surfaces and surface films
• It has its own importance in studying the surface structures of thin
films
• Particularly this technique is more effective for gases and vapours for
measuring the bond distances and bond angles
• It also gives information about electron distribution in the given
sample
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14. ADVANTAGES OVER X-RAY
• Being less penetrate than X-Rays , their interaction with the
surface level is more intimate.
• In electron diffraction the intensity of diffraction pattern is
high and so only very short exposure times are necessary when
compared to that of X-rays
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15. NEUTRON DIFFRACTION
• Neutron diffraction is the application of neutron scattering to
the determination of the atomic structure of the material
• When a beam of neutrons emanating from a reactor is slowed
down and selected properly by their speed, their wavelength
lies near one angstrom (0.1 nanometer), the typical separation
between atoms in a solid material. Such a beam can then be
used to perform a diffraction experiment.
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16. INSTRUMENTATION
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It consists mainly of neutron source, monochromator and
detector.

17. WORKING
• The technique requires a source of neutrons. Neutrons are
usually produced in a nuclear reactor or spallation source.
• At a research reactor, other components are needed, including
a crystal monochromators, as well as filters to select the
desired neutron wavelength.
• Sample requirement: Single crystal work is also possible, but
the crystals must be much larger than those that are used in
single-crystal X-ray crystallography.
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18. TYPES OF SCATTERING
Nuclear scattering
Magnetic scattering
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19. NUCLEAR SCATTERING
• Nuclear scattering is due to the interaction of neutrons with atomic
nuclei
• Neutrons interact directly with the nucleus of the atom, and the
contribution to the diffracted intensity depends on each isotope; for
example, regular hydrogen and deuterium contribute differently.
• It is also often the case that light (low Z) atoms contribute strongly
to the diffracted intensity, even in the presence of large Z atoms.
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20. MAGNETIC SCATTERING
• Although neutrons are uncharged, they carry a magnetic moment,
and therefore interact with magnetic moments, including those
arising from the electron cloud around an atom.
• Neutron diffraction can therefore reveal the microscopic magnetic
structure of a material.
• Magnetic scattering requires an atomic form factor as it is caused
by the much larger electron cloud around the tiny nucleus.
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21. Graphical plot
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22. APPLICATIONS
• Used for locating light atoms
• Used for detecting isotopes of same atomic number
• Neutron activation analysis (NAA) is a nuclear process used
for determining the concentrations of elements in a vast
amount of materials.
• Highly penetrating: Measure bulk properties can benefit
from large samples
• Main advantage is to study the magnetic properties of the
compounds comprised of transition metal series 22

23. `
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Electron diffractionNeutron diffraction

24. REFERENCES
• Introduction to advanced inorganic chemistry by
P.J.DURRANT and B.DURRANT
• Solid state chemistry by R.WEST and ANTHONY
• Wikipedia-diffraction techniques
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25. Thank you..
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