X-Ray Diffraction

Question 1

Generation of X-rays

Answer 1

Electrons accelerated towards metal target = anode
Rapid deceleration though multiple collusions
Emit radiation
Water cooled ‘sealed tube’ removes excess thermal energy
Wavelength of radiation depends on acceleration voltage

Question 2

Kα peaks

Answer 2

Descent of electron from L to K

Question 3

Kβ peaks

Answer 3

Descent of electron from M to K

Question 4

Generating monochromatic X-rays

Answer 4

β-filter, filters out Κβ radiation, use element in periodic table before the anode material
Crystal monochromator = white source radiation passed through monochromator, orient monochromator so only Kα radiation is scattered towards single crystal and the unwanted radiation is absorbed by the monochromator housing

Question 5

Diffraction pattern

Answer 5

Pattern of radiation scattered by an object

Question 6

Relationship between diffraction pattern and dimensions of the slit

Answer 6

Smaller slit = larger spread

Question 7

Constructive interference

Answer 7

Combination of two waves that are fully in phase

Question 8

Partially constructive interference

Answer 8

Combination of two waves with λ/4 phase difference

Question 9

Destructive interference

Answer 9

Combination of two waves with λ/2 phase difference

Question 10

Increase number of slits

Answer 10

Sharper image

Question 11

Bragg equation

Answer 11

Parallel incident X-rays hit parallel pair of planes with an inter planar spacing of d, max intensity when angle of incidence = angle of reflection, nλ=2dsinθ