The central problem in diffraction methods is to interpret the data obtained from diffraction experiments and identify uniquely the nature of the crystal responsible for the diffraction pattern. Nowadays, there are standard softwares built into the diffractometers which just about give a printout of the three dimensional structure. In this lecture we will illustrate some important features and concepts involved in this process.
We know from Bragg's law that n
= 2d h k lsin
and dh k l = a [ h2 + k2 + l 2 ] -1/ 2 where dh k l is the perpendicular distance between two adjacent Miller planes and a is the edge length of the unit cell of a cubic lattice. These two equations can be combined to give
sin = (h2 + k2 + l 2 ) 1/ 2 / 2a
(19.1)
For each hkl plane present in the crystal, there will be a maximum intensity corresponding to in Eq (19.1).
= 2d h k lsin
and dh k l = a [ h2 + k2 + l 2 ] -1/ 2 where dh k l is the perpendicular distance between two adjacent Miller planes and a is the edge length of the unit cell of a cubic lattice. These two equations can be combined to give 
