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COMPUTER SCIENCE ENGINEERING
ENGINEERING PHYSICS
TOPICS COVERED- BRAGG’S SPECTROMETER
X RAYS AND THEIR TYPES, CRYSTALLINE AND
AMORPHOUS SOLIDS AND TYPES OF CRYSTAL
LATTICE (BRAVIS LATTICES).
1
Bragg's Spectrometer
Bragg's Spectrometer is used to determine the wavelength of X-Rays incident on a material.
Its structure is very similar to an optical spectrometer. In Bragg's spectrometer, X-rays from an X-Ray Tube pass through two fine slits, S1 and S2, to form a fine single ray.
This fine X-Ray beam is directed onto a crystal (C) mounted on the spectrometer table (T). This table has the capability to rotate about its vertical axis, and its rotation can be observed from a circular graduated scale attached to the table.
The reflected beam from the crystal passes through S3 and S4 slits, which then enters the ionization chamber (IC). The X-rays entering the ionization chamber ionize the gas present, leading to the formation of a current.
This current is measured to determine the intensity of the X-rays reflected by the crystal. (Mostly X-ray diffraction 10-90) SAXS Small angle x-ray spectroscopy.
DIAGRAM:
COMPUTER SCIENCE ENGINEERING
ENGINEERING PHYSICS
TOPICS COVERED- BRAGG’S SPECTROMETER
X RAYS AND THEIR TYPES, CRYSTALLINE AND
AMORPHOUS SOLIDS AND TYPES OF CRYSTAL
LATTICE (BRAVIS LATTICES).
2
COMPUTER SCIENCE ENGINEERING
ENGINEERING PHYSICS
TOPICS COVERED- BRAGG’S SPECTROMETER
X RAYS AND THEIR TYPES, CRYSTALLINE AND
AMORPHOUS SOLIDS AND TYPES OF CRYSTAL
LATTICE (BRAVIS LATTICES).
4
● Cathode: Its primary work is to produce an electron beam which strikes the anode material. For this, the cathode uses thermionic emission.
Glass Envelope: The cathode and anode are put in an airtight glass envelope. It also provides electrical insulation to the anode and cathode assemblies. On the contrary, if gases are present in the tube, they will aid in the conduction of electricity.
Housing: The housing of X-Ray tubes encloses and supports other components. The space between the housing and the X-ray tube is filled with oil, which provides electrical insulation and heat transfer from the tube to the housing surface^35.
X-RAY TUBE: It is an energy converter which converts electrical energy into two forms:
➔ X-Rays and 98% heat. As the current flows from the tube from cathode to anode, electrons undergo energy loss which leads to the production of X-Rays.
Definition of X-Rays: X-Rays are electromagnetic waves having wavelengths between X-rays up to 30 keV are known as soft X-Rays. After that, up to 110 eV, they are known as hard X-Rays.
There are two types of X-Rays:
COMPUTER SCIENCE ENGINEERING
ENGINEERING PHYSICS
TOPICS COVERED- BRAGG’S SPECTROMETER
X RAYS AND THEIR TYPES, CRYSTALLINE AND
AMORPHOUS SOLIDS AND TYPES OF CRYSTAL
LATTICE (BRAVIS LATTICES).
5
- Continuous X-Ray
- Characteristic X-Ray
In continuous X-Rays , the X-Rays are emitted when high-speed electrons from the source interact with the nucleus of the target and lose their energy due to electrostatic interaction^44.
Characteristics X-Rays: These are monochromatic, high intensity with constant wavelength^45. These X-rays are produced when high-energy particles such as electrons, protons, or ions are bombarded onto an element^46.
This leads to striking out of the outermost electrons of the target^47.
Crystalline Solids:
● It is formed by the regular repetition of its building blocks such as atoms and/or molecules in a three-dimensional array^48.
● Crystalline solids show periodicity^49. For example, NaCl, metals, ceramics, etc. 50
Amorphous Solids:
● In these kinds of solids, atoms and molecules are not arranged in a periodic manner over a long range^51.
● Sometimes periodicity can be observed over a small range, but it is not sufficient.
● For example, glasses, rubbers, polymers, plastics, etc.
● Unit Cell: Consists of lattice and basis.
COMPUTER SCIENCE ENGINEERING
ENGINEERING PHYSICS
TOPICS COVERED- BRAGG’S SPECTROMETER
X RAYS AND THEIR TYPES, CRYSTALLINE AND
AMORPHOUS SOLIDS AND TYPES OF CRYSTAL
LATTICE (BRAVIS LATTICES).
7
2D: There are five types of 2D crystal lattices:
- Square
- Rectangle
- Centered Rectangle
- Hexagonal
- Oblique
3D: There are seven types of crystal systems in 3D crystal lattices , which are further divided into 14 types of lattices, each known as Bravais lattices.
- Tetragonal
- Hexagonal
- Monoclinic
- Triclinic
- Rhombohedral
- Orthorhombic
- Cubic
Cubic:
COMPUTER SCIENCE ENGINEERING
ENGINEERING PHYSICS
TOPICS COVERED- BRAGG’S SPECTROMETER
X RAYS AND THEIR TYPES, CRYSTALLINE AND
AMORPHOUS SOLIDS AND TYPES OF CRYSTAL
LATTICE (BRAVIS LATTICES).
8
● Simple ● Body Centered (BCC) ● Face Centered (FCC) 81
Tetragonal:
● Simple ● Body Centered
Orthorhombic:
● Simple ● BCC ● FCC ● End Centered
The following table:
● Monoclinic: Simple ● End centered
● Hexagonal: Simple
● Triclinic: Simple
● Rhombohedral: Simple
Diagram:
Cubic :
a=b=c
α=β=γ=90 degree
COMPUTER SCIENCE ENGINEERING
ENGINEERING PHYSICS
TOPICS COVERED- BRAGG’S SPECTROMETER
X RAYS AND THEIR TYPES, CRYSTALLINE AND
AMORPHOUS SOLIDS AND TYPES OF CRYSTAL
LATTICE (BRAVIS LATTICES).
10
Eg. Zinc, Magnesium Etc.
● Monoclinic: α=γ=90∘ not equal to beta, ● a=b=c (not equal)
Triclinic:
a=b=c (not equal)
α=β=γ (not equal)
For example, K2Cr2O
● Trigonal or Rhombohedral:
α=β=γ<120 degree not equal to 90∘
a=b=c
● DIAGRAM ILLUSTRATIONS-
COMPUTER SCIENCE ENGINEERING
ENGINEERING PHYSICS
TOPICS COVERED- BRAGG’S SPECTROMETER
X RAYS AND THEIR TYPES, CRYSTALLINE AND
AMORPHOUS SOLIDS AND TYPES OF CRYSTAL
LATTICE (BRAVIS LATTICES).
11
COMPUTER SCIENCE ENGINEERING
ENGINEERING PHYSICS
TOPICS COVERED- BRAGG’S SPECTROMETER
X RAYS AND THEIR TYPES, CRYSTALLINE AND
AMORPHOUS SOLIDS AND TYPES OF CRYSTAL
LATTICE (BRAVIS LATTICES).
13
