XRD

X-ray Diffraction Technique: 

X-ray Diffraction Technique Presentation By Rakesh Gullapelli M.Pharm (Pharmaceutics) Department of Pharmaceutics School of Pharmacy ( Lalitha ) Anurag Group of Institutions Hyderabad

CONTENTS: 

CONTENTS INTRODUCTION GENERATION OF X-RAYS X-RAY TECHNIQUES PRINCIPLE INSTRUMENTATION APPLICATIONS CONCLUSIONS ACHIEVEMENTS REFERENCES 2

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INTRODUCTION: X-rays are discovered by Wilhelm Roentgen who called them x-rays because the nature at first was unknown so, x-rays are also called Roentgen rays. X-ray diffraction was discovered by Max.The wavelength range is 10 -7 to about 10 -15 mts . The penetrating power of x-rays depends on energy also, there are two types of x-rays. i ) Hard x-rays : which have high frequency and have more energy. ii) soft x-rays : which have less penetratig and have low energy 3

X-RAYS: 

X-RAYS 1 .X-rays are short wave length electromagnetic radiations produced by the deceleration of high energy electrons or by electronic transitions of electrons in the inner orbital of atoms 2 .X-ray region 0.1to100 A ˚ 3 .Analytical purpose 0.7 to 2 A ˚ 4

GENERATION OF X-RAYS: 

GENERATION OF X-RAYS By bombarding matter by High energy electrons X-ray photons By use of radioactive source From synchrotron radiation Cornell-high-energy synchrotron radiation laboratory Stanford synchrotron radiation laboratory Brookhaven national laboratory 5

X-RAY TECHNIQUES: 

X-RAY TECHNIQUES X-RAY ABSORPTION METHOD X-RAY DIFFRACTION METHOD X-RAY FLOURESCENCE METHOD 6

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RAY DIFFRACTION

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Max Theodor Felix von Laue (9 October 1879 – 24 April 1960) was a German physicist who won the Nobel Prize in Physics in 1914 for his discovery of the diffraction of X-rays by crystals . 8

PRINCIPLE: 

PRINCIPLE X-ray diffraction is based on constructive interference of monochromatic x-rays and a crystalline sample. These x-rays are generated by a cathode ray tube, filtered to produce monochromatic radiation ,collimated to concentrate and directed towards the sample. The interaction of incident rays with the sample produces constructive interference when conditions satisfy Bragg’s law. 9

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BRAGG’s EQUATION d     dSin  The path difference between ray 1 and ray 2 = 2d Sin For constructive interference: n = 2d Sin Ray 1 Ray 2  Deviation = 2  10

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“ Constructive interference of the reflected beams emerging from two different planes will take place if the path lengths of two rays is equal to whole number of wavelengths”. for constructive interference, n λ =2dsin Ф this is called as BRAGG’S LAW 11

INSTRUMENTATION: 

INSTRUMENTATION Production of x-rays Collimator Monochromator a.Filter b.Crystal monochromator Detectors a.Photographic methods b.Counter methods Geiger muller tube counter Proportional counter Scintillation counter Solid state semi-conductor detector Semi-conductor detectors 12

Instrumentation of XRD: 

Instrumentation of XRD 13

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PRODUCTION OF X-RAYS: X-rays are generated when high velocity electrons impinge on a metal target. Approximately 1% of the total energy of the electron beam is converted into x-radiation. The remainder being dissipated as heat. Many types of x-ray tubes are available which are used for producing x-rays. 14

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Coolidge tube It consists of a Cathode which is a filament of tungsten metal heated by a battery B to emit the thermoionic electrons.This beam of electrons constitutes the cathode ray stream.If a positive voltage in the form of an anode(target) is kept near these electrons,the electrons are accelerated towards anode.On striking the anode, electrons transfer their energy to its metallic surface which then gives off X-rays . 15

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X-ray production at instrumental level 16

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COLLIMATOR: In order to get a narrow beam of x-rays, the x-rays generated by the target material are allowed to pass through a collimator which consists of two sets of closely packed metal plates separated by a small gap. The collimator absorbs all the x-rays except the narrow beam that passes between the gap. 17

TYPES OF MONOCHROMATORS: 

TYPES OF MONOCHROMATORS In order to do monochromatization,2 methods are available 1.Filter 2.Crystal monochromator a)Flat crystal monochromator b)Curved crystal monochromator Materials used- Nacl,LiF,quartz etc,. 18

DETECTORS: 

DETECTORS The x-ray intensities can be measured and recorded either by photographic or counter methods. Both these types of methods depends upon ability of x-rays to ionize matter and differ only in the subsequent fate of electrons produced by the ionizing process. 19

DETECTORS: 

DETECTORS Photographic methods D= logIo /I Counter methods Geiger- muller tube counter Proportional counter Scintillation detector Solid-state semi-conductor detector Semi conductor detectors:si (Li) & Ge (Li) 20

A) photographic method: : 

A) photographic method: In order to record position and intensity of x-ray beam a plane cylindrical film is used. The film after exposing to x-rays is developed,the blackening of the developed field is expressed in terms of density units D given by D=logIo/I D is related to the total x-ray energy that causes the blackening of the photographic film and measured by densitometer. . 21

B) Counter methods:: 

B) Counter methods: These are of many types, like Geiger-muller tube counter Proportional counter Scintillation counter Solid-state semiconductor detector Semiconductor detector 22

a) Geiger-muller tube counter: 

a) Geiger- muller tube counter Filled with inert gases like argon. Positive potential of 800-2500 Volts ADVANTAGES: inexpensive,trouble free detector,higher signal. DISADVANTAGES: used only for counting low rates,efficiency falls off rapidly at λ <1A°,cannot be used to measure energy of ionising radiation. 23

b) Proportional counter: : 

b) Proportional counter: Construction is similar to Geiger-tube counter only but proportional counter is filled with a heavier gas like xenon or krypton. Heavier gas is preferred because it is easily ionised. 24

c) Scintillation counter: 

c) Scintillation counter In this detector, there is a large sodium iodide crystal activated with a small amount of thallium. When x-rays incident upon crystal, the pulses of visible light are emitted which can be detected by photomultiplier tube. 25

SCINTILLATION DETECTOR: 

SCINTILLATION DETECTOR 26

d)Solid state semi-conductor detector: 

d)Solid state semi-conductor detector The electrons produced by X-ray beam are promoted into conduction bands and the current which flows is directly proportional to the incident X-ray energy . Disadvantage: Mainted at very low Temp to minimise the noise and prevent deterioration of the detector. 27

e) Semi-conductor detectors: 

e) Semi-conductor detectors When x-ray falls on a semiconductor or a silicon lithium-drifted detector,it generates an electron(-e) and a hole(+e) in a fashion analogous to the formation of a primary ion pair in a proportional counter. The principle is similar to that of gas ionization detector as used in a proportional counter, except that the materials used are in a solid state. 28

X-RAY DIFFRACTION METHODS: 

X-RAY DIFFRACTION METHODS These are generally used for investigating the internal structures and crystal structures of various solid compounds. They are 1.Laue’s photographic method a)Transmission method b)Back reflection method 2.Bragg’s X-ray spectrometer method 3.Rotating crystal method 4.Powder method 29

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b)Back-reflection method: 

b)Back-reflection method This method is similar to Transmission method . However, black-reflection is the only method for the study of large and thick specimens. Disadvantage: Big crystals are required 31

2)Bragg’s x-ray spectrometer method:: 

2)Bragg’s x-ray spectrometer method : This method is based on Bragg’s law, bragg analysed the structures of Nacl,KaI and ZnS . 32

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APPLICATIONS: 

APPLICATIONS Structure of crystals Polymer characterisation State of anneal in metals Particle size determination Spot counting method Broadening of diffraction lines Low-angle scattering 5.Applications of diffraction methods to complexes Determination of cis-trans isomerism Determination of linkage isomerism 6.Miscellaneous applications 35

1.STRUCTURE OF CRYSTALS: 

1.STRUCTURE OF CRYSTALS a -x-ray pattern of salt Nacl b -x-ray pattern of salt Kcl c -x-ray pattern of mixture of Nacl &Kcl d -x-ray pattern of a powder mixed crystal of Nacl & Kcl 36

2.POLYMER CHARACTERISATION: 

2.POLYMER CHARACTERISATION Determine degree of crystanillity Non-crystalline portion scatters x-ray beam to give a continuous background(amorphous materials) Crystalline portion causes diffraction lines that are not continuous.(crystalline materials) 37

3.State of anneal in metals:XRD is used to to test the metals without removing the part from its position and without weakening it.: 

3.State of anneal in metals: XRD is used to to test the metals without removing the part from its position and without weakening it. 4.PARTICLE SIZE DETERMINATION Spot counting method: v=V. δθ . cos θ /2n V =volume of individual crystallite V=total volume irradiated n=no. of spots in diffraction ring δθ =divergence of x-ray beam 38

APPLICATIONS OF DIFFRACTION METHODS TO COMPLEXES: 

APPLICATIONS OF DIFFRACTION METHODS TO COMPLEXES a)Determination of cis -Trans Isomerism : Bis (pyridine-2-carboxamido) nickle (II) chloride b)Determination of linkage isomerism : Biuret+copper (II)= pottassiumbis ( biureto ) cuprate (II) tetrahydrate 39

MISCELLANEOUS APPLICATIONS: 

MISCELLANEOUS APPLICATIONS Soil classification based on crystallinity Analysis of industrial dusts Assessment of weathering & degradation of minerals & polymers Study of corrosion products Examination of tooth enamel & dentine Examination of bone state & tissue state Structure of DNA&RNA 40

CONCLUSIONS: 

CONCLUSIONS For materials including metals, minerals, plastics, pharmaceuticals and semiconductors XRD apparatus provide highly accurate tools for non-destructive analysis. The diffraction systems are also supported by an extensive range of application software 41

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X-ray diffraction pattern for a single alum crystal. Image by Dr H. J. Milledge , Department of Geology, University College, London

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X-ray diffraction image of a crystal of lysozyme 43

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Bruker's X-ray Diffraction D8-Discover instrument

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1895 W.C. Roentgen discoversed X-rays ( Nobel Prize 1901 ) 1910 Max von Laue: Diffraction Theory ( Nobel Prize: 1912 ) 1915 W.L. Bragg & W.H. Bragg: NaCl , KCl ( Nobel Prize Physics ) 2 • d • sin Θ = n • λ 1934 D. Bernal & D. Crowfoot examine first Proteins 1950 DNA double helix structure: Watson, Crick, Wilkins ( Nobel Prize 1963 ) 1958 Myoglobin Structure ( Nobel Prize 1962 Kendrew, Perutz) 1971 Insulin (Blundell) 1978 First Virus Structure (S.C Harrison) 1988 Nobel Prize : Photosynthetic reaction center (Huber, Michel, Deisenhofer) 1997 Nobel Prize : ATP- synthase structure (Walker) 1997 Nucleosome core particle (T. Richmond) 1999 Ribosome Structures ( Steitz , …) 2000 Reovirus core structure (S.C. Harrison) 2000 Rhodopsin structure, GPCR ( Palczewski et al.) 2002 ABC-Transporter (D. Rees et al.) 2003 R.MacKinnon : structures of ion channel ( Nobel Prize Chemistry 2003 ) X-Ray diffraction achievements 48

REFERENCES: 

REFERENCES 1)Instrumental methods of chemical analysis ,B.K.sharma,17 th edition 1997-1998,GOEL publishing house.page no:329-359 2)Principles of instrumental analysis,5 th edition ,by Dougles a.skoog,f.James holles,Timothy A.Niemen.page no:277-298 3)Instrumental methods of chemical analysis , Gurudeep R.chatwal,sham k.anand,Himalaya publications page no:2.303-2.332 4) Instrumental Methods Of Chemical Analysis – H. Kaur pg.no:727-729,737 5) http://www.scienceiscool.org/solids/intro.html 6) http://en.wikipedia.org/wiki/X-ray_crystallography 48

TanQ: 

TanQ ANY QUERIES… 49