Introduction
to
to
X-ray Diffraction (XRD)
Historical
Perspective
1912:
Maxwell von Laue first discovered X-ray
diffraction
- determined that
X-rays would be scattered by atoms in a
crystalline solid if there was similarity in the
wavelength
of X-rays and the interatomic distances of the
crystalline material.
1913:
Sir William H. Bragg and and his son Sir W.
Lawrence Bragg derived the equation known as
Bragg’s Law to define diffraction as a function
of the angle of incidence
2d sinq = nl
l = wavelength of the x-ray
q = scattering angle
n = integer representing the order of the diffraction peak
d = inter-plane distance of (i.e atoms, ions, molecules)
-determined why
the cleavage faces of crystals appeared to
reflect X-ray beams at certain angles of
incidence (q).
This is due to constructive interference.
- simulated the
experiment, using visible light and tiny arrays
of dots and pinholes to mimic atomic
arrangements on a
much larger scale.
These experiments provided similar
patterns to X-rays but were safer to work with
than X-rays.
1914:
von Laue
awarded Nobel Prize for discovery of X-ray
diffraction by crystals and showing X-rays are
electromagnetic waves
1915:
Braggs awarded Nobel Prize for their work
determining the crystal structure of diamond,
NaCl and ZnS.
Celeste Morris, Bradley Sieve and Heather Bullen, Department of Chemistry, Northern Kentucky University, Highland Heights, KY 41099