Question

8.1. What is the resolution and observed scattering angle of the {21 0 15} reflection from a cubic crystal with a unit cell length of 79 Å when using Cu-Kα radiation (λ=1.5418 Å)?

Answer 1

From Bragg's law, n = 2dsin, where is the scattering angle, d is the distance between two consecutive planes, n is an interger, which denotes order of reflection and is the wavelength of incident radiation.

Also d= a/(h²+k²+l²)^1/2 where a is the unit cell length and h, k, l are the lattice parameters. From this equation, d= 3.06

Thus sin= / 2d = 0.2519;   = 14.59, which is the observed scattering angle.

d= 3.06 is called the resolution of the X-ray scattering experiment.