Neutron Diffaraction
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Majmaah University Department of Physics College of Science, Al-Zulfi KINGDOM OF SAUDI ARABIA 1. X-Ray Diffraction 2. Electron Diffraction 3. Neutron Diffraction Friday, July 1, 2016 Prof. Dr. Abdul Majid 1 Majmaah University Department of Physics College of Science, Al-Zulfi KINGDOM OF SAUDI ARABIA Crystal Diffraction Neutron Diffraction • Why Neutron for Crystal Diffraction • Production/Source of Neutron • Applications of Neutron Friday, July 1, 2016 Prof. Dr. Abdul Majid 2 Majmaah University Department of Physics College of Science, Al-Zulfi KINGDOM OF SAUDI ARABIA Crystal Diffraction Bragg’s Law ππ = ππ πΊππ π½ Friday, July 1, 2016 Prof. Dr. Abdul Majid 3 Majmaah University Department of Physics College of Science, Al-Zulfi KINGDOM OF SAUDI ARABIA Crystal Diffraction Bragg’s Law ππ = ππ πΊππ π½ Friday, July 1, 2016 Prof. Dr. Abdul Majid 4 Majmaah University Department of Physics College of Science, Al-Zulfi KINGDOM OF SAUDI ARABIA Neutron Crystal Diffraction Why use neutrons? Neutron waves are diffracted by the consecutive layers of atoms in a crystal - this provides information on the structure of the crystal. When beams of neutrons are used to probe small samples of materials they have the power to reveal what cannot be seen using other types of radiation. Neutrons appear to behave either as particles or as waves or as microscopic magnetic dipoles. It is these specific properties which enable them to yield information which is often impossible to obtain using other techniques. Majmaah University Department of Physics College of Science, Al-Zulfi KINGDOM OF SAUDI ARABIA Neutron Crystal Diffraction Electrically Neutral – neutrons are non-destructive and can penetrate deep into matter. This makes them an ideal probe for biological materials and samples under extreme conditions of pressure, temperature, magnetic field or within chemical reaction vessels. Microscopically Magnetic – they possess a magnetic dipole moment which makes them sensitive to magnetic fields generated by unpaired electrons in materials. Precise information on the magnetic behaviour of materials at atomic level can be collected. In addition, the scattering power of a neutron off an atomic nucleus depends on the orientation of the neutron and the spin of the atomic nuclei in a sample. This makes the neutron a powerful instrument for detecting the nuclear spin order. Majmaah University Department of Physics College of Science, Al-Zulfi KINGDOM OF SAUDI ARABIA Neutron Crystal Diffraction Ångstrom wavelengths – neutron wavelengths range from 0.1 Å to 1000 Å, making them an ideal probe of atomic and molecular structures, be they single atomic species or complex biopolymers. Energies of millielectronvolts – their energies are of the same magnitude as the diffusive motion in solids and liquids, the coherent waves in single crystals (phonons and magnons), and the vibrational modes in molecules. It is easy to detect any exchange of energy between a sample of between 1microeV (even 1 neV with spin-echo) and 1eV and an incoming neutron. Randomly sensitive – with neutrons the variation in scattering power from one nucleus to another within a sample varies in a quasi-random manner. This means that lighter atoms are visible despite the presence of heavier atoms, and neighbouring atoms may be distinguished from each other. In addition, contrast can be varied in certain samples using isotopic substitution (for example D for H, or one nickel isotope for another); specific structural features can thus be highlighted. The neutron is particularly sensitive to hydrogen atoms; it is therefore a powerful probe of hydrogen storage materials, organic molecular materials, and biomolecular samples or polymers. Majmaah University Department of Physics College of Science, Al-Zulfi KINGDOM OF SAUDI ARABIA Neutron Crystal Diffraction Neutrons are used in different fields of research. • • • • Condensed-matter physics, materials science and chemistry Biosciences Nuclear and elementary particle physics Engineering sciences Majmaah University Department of Physics College of Science, Al-Zulfi KINGDOM OF SAUDI ARABIA Neutron Crystal Diffraction Condensed-matter physics, materials science and chemistry • Examination of the structure of new materials, for example new ceramic high-temperature superconductors or magnetic materials (important for electronic and electrical applications). • Clarification of still unknown phenomena in processes such as the recharging of electric batteries. • Storing of hydrogen in metals, an important feature for the development of renewable energy sources. • Analysis of important parameters (for example elasticity) in polymers (for example plastic material). • Colloid research gives new information on such diverse subjects as the extraction of oil, cosmetics, pharmaceuticals, food industry and medicine. Biosciences • Biological materials, naturally rich in hydrogen and other light elements, are ideal samples for analysis with neutrons. , Cell Membranes, Proteins, Virus, Investigations Photosynthesis in Plants Nuclear and elementary particle physics • Experiments on the physical properties of the neutron and the neutrino. • Production of extremely slow neutrons down to 5 m/s (the velocity of the neutrons which leave the reactor is generally about 2200 m/s). This enables completely new experiments to be performed with such particles. • Experiments on atomic fission and the structure of nuclei. Engineering sciences • Since neutron diffraction is non-destructive, it is ideal for the analysis of different technical phenomena in materials. • Visualisation of residual stress in materials (example: railway rails). • Hardening and corrosion phenomena in concrete, Inhomogeneity and trace elements in materials. Majmaah University Department of Physics College of Science, Al-Zulfi KINGDOM OF SAUDI ARABIA Neutron Crystal Diffraction Majmaah University Department of Physics College of Science, Al-Zulfi KINGDOM OF SAUDI ARABIA Neutron Crystal Diffraction Majmaah University Department of Physics College of Science, Al-Zulfi KINGDOM OF SAUDI ARABIA Neutron Crystal Diffraction Majmaah University Department of Physics College of Science, Al-Zulfi KINGDOM OF SAUDI ARABIA Neutron Crystal Diffraction Majmaah University Department of Physics College of Science, Al-Zulfi KINGDOM OF SAUDI ARABIA Neutron Crystal Diffraction Majmaah University Department of Physics College of Science, Al-Zulfi KINGDOM OF SAUDI ARABIA Friday, July 1, 2016 Prof. Dr. Abdul Majid 15 Majmaah University Department of Physics College of Science, Al-Zulfi KINGDOM OF SAUDI ARABIA Friday, July 1, 2016 16
