41 - OBJECTIVE The objective of this experiment is to learn...

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OBJECTIVE The objective of this experiment is to learn how atoms are arranged in some common crystals and how this arrangement determines the way in which a particular crystal diffracts X-rays.Moreover we have another objective namely to find an unknown material by using X-ray diffraction. APPARATUS X-ray diffractometer SAMPLE USED An unkown sample THEORY Most of our knowledge regarding the atomic and molecular arrangements in solids has resulted from X-ray diffraction investigations.Before X-ray diffraction we have to say something about the X-rays , the production and detection of X-rays and the geometry of crystals. X –rays were discovered in 1895 by the German physicist Röntgen and were so named becouse their nature was unknown at that time.Although X-rays were discovered in 1895 the determination of crystal systems and interatomic distance of an unknown material by X-ray diffraction method is discovered in 1912.Unlike ordinary light , these rays were invisible,but they traveled in straight lines and affected photographic film in the same way as light.On the other hand ,they were much more penetrating then light and could easily pass through the human body,quite thick pieces of metal and other opaque objects. Now we understood the nature of X-rays.But how we produce these rays?We can produce X-rays whenever a high speed electron strike to a metal target.For our aim(production of these rays)we arrange X-ray tubes.Any X-ray tube must contain: A source of electrons A high accelareting voltage A metal target
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After these knowledge of course the detection of these rays are also important for us.The principal means used to detect X-ray beams are: Fluorcent screens Photographic film Ionization Devices By using X-rays we can gain knowledge about geometry of crystals so we have to talk about this issue and give some definitions.A crystal may be defined as a solid composed of atoms arranged in a pattern periodic in three dimensions The crystal
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41 - OBJECTIVE The objective of this experiment is to learn...

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