NEUTRON DIFFRACTION METHOD techniques .pptx

About neutron diffraction method

1. NEUTRON DIFFRACTION METHOD SUBMITTED BY, MACDELIN BELSIYA.S I – M.SC., CHEMISTRY

2. Neutron diffraction is a technique used to study the structure of materials at the atomic and molecular level. It involves directing a beam of neutrons at a sample and measuring the scattering pattern produced as the neutrons interact with the atomic nuclei in the sample. This scattering pattern provides information about the positions of atoms within the sample, allowing scientists to determine its atomic structure, crystallographic properties, magnetic ordering, and other properties. NEUTRON DIFFRACTION METHOD

3. Neutron Diffraction is particularly useful for studying materials with large unit cells, complex structure, and those containing light elements such as hydrogen.

5. Neutrons and electrons travelling at suitable velocities have wavelengths of the order of 100-200 pm and thus undergo diffraction by crystalline inorganic compounds. Neutron beams of the appropriate wavelength are generated by ‘moderating’ (slowing down) neutrons generated in nuclear reactors or through a process known as spallation, in which neutrons are chipped off the nuclei of heavy elements by accelerated beams of protons. The instrumentation used for collecting data and analyzing single-crystal or powder neutron diffraction patterns is often similar to that used for X-ray diffraction.

6. Fig. Instrumentation of neutron diffraction Technique

7. Neutron source: Produces neutrons Monochromator: Sorts out discrete wavelength Diffractometer: Allows neutron to interact with sample Detector: Pick up neutrons scattered from the sample

8. WORKING: The technique requires a source of neutrons. Neutrons are usually produced in a nuclear reactor or spallation source. The source of neutron passed through the monochromator, and the monochromatized beam is made to fall on the Sample. Filters are also used to select desired neutron wavelength.

9. The sample is placed within a neutron beam and the angles at which the neutrons are deflected or scattered by the material are recorded to generate a ‘Diffraction Pattern’ from which structural information can be extracted. 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.

10. The difference between the X-ray and neutron diffraction techniques lies in the scattering process: X-rays are scattered by the electrons around the nucleus, whereas neutrons are scattered by the nucleus. XRD uses X-rays, which are electromagnetic radiation. Neutron diffraction uses neutron, which are subatomic particles. X-rays have a shorter wavelength and higher energy compared to neutrons, allowing them to penetrate deeper into materials are suitable for studying crystalline structures in solids. Neutrons, being uncharged, penetrate deeply into materials and are particularly useful for studying the bulk properties of materials, such as the arrangement of atoms and magnetic structures.

11. Neutron diffraction is more sensitive to light elements like hydrogen, which have low X-ray scattering factors. This makes neutron diffraction particularly useful for studying materials containing hydrogen or other light elements. X-ray diffraction is widely used in the study of crystalline materials, including determining crystal structures, identifying phases, and analyzing crystal defects.

12. Neutron diffraction is especially valuable for investigating magnetic structures, studying materials containing hydrogen, probing materials at extreme conditions(such as high pressure or temperature), and examining biological systems.

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