Chapter 12, Problem 12.35QP

Interpretation Introduction

Interpretation:

The wavelength of X-rays used in an experiment involving $\text{NaCl}$ has to be determined.

Concept introduction:

               The structure of a crystalline solid can be determined by X-ray diffraction method using the Bragg equation,

                                  Where,   $\begin{array}{l}\text{nλ}\text{=}\text{2d}\text{sinθ}\\ \\ \text{n}\text{=}\text{order of diffraction, positive integer}\text{.}\\ \lambda \text{=}\text{wavelength of incident light}\text{.}\\ \text{d =}\text{interplanar distance of a crystal}\text{.}\\ \theta =\text{angle of incident light}\text{.}\end{array}$

Bragg equation was derived from Bragg’s law which states –

“When X-ray is incident onto a crystal surface, the angle of incidence $\text{θ}$ gets reflected back with similar angle $\text{θ}$ which is known as angle of scattering.  When the path difference is equal to the whole number, constructive interference occurs.”