Chapter 12, Problem 12.131QP

Interpretation Introduction

Interpretation:

The angle of reflection for the crystal having interplanar distance of $\text{312 pm}$ has to be calculated.

Concept Introduction:

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

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

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.”