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Secret Behind Bragg's law (nλ = 2dsinθ) - Reflected angle vs. Diffracted angle

Reflection and Diffraction are the two confusing words in XRD analysis & Bragg law (nλ = 2dsinθ). Let's explain it❗ Here, the focus is only on XRD analysis (Bragg law, nλ = 2dsinθ) Diffraction is more complex phenomena than the Reflection. Diffraction is sometimes also confused with Scattering. The diffraction is the special or sub-type of Scattering! ✅ NO 1:✍ ⇒ Reflection only takes place from the surface / thin surface layer / layers of atomic planes ⭕ ⇒ Diffraction take place through the entire bulk volume of the sample (here the x-rays is scattered by the electrons → atoms → unit cells in all directions and in some directions, the scattered incident x-rays are in phase and reinforce each other, therefore, forming the diffracted beam). ✅NO 2:✍ ⟹ Reflection takes place at any angle, i.e., there are NO fast and hard rules that some condition must be satisfied for Reflection to occur⭐ ⟹ Diffraction takes place at those particular incident angles (at angles where the Bragg law satisfied and we get XRD peaks) ✅NO 3:✍ ⇒ In reflection, ~100 % of the intensity may be reflected from the surface (depends on the nature of the surface) ⇒ In diffraction, only a SMALL fraction of the intensity is diffracted (this mean that most of the radiations are absorbed by the sample or scattered in directions where the reinforcement is NOT occurs i.e., destructive interference occurs and NO PEAKS)! Finally, let's discuss briefly the diffraction and scattering in XRD analysis. A diffracted beam is composed of a large number of scattered x-rays mutually reinforcing each other. Therefore, diffraction is essentially a scattering phenomenon as we know that atoms scatter incident x-rays in all directions and in some directions, these scattered beam are in complete phase and reinforce each other, forming the diffracted beam! Very important! Please NOTE the following points❓❌❎ We usually use "reflecting planes" and "reflected beams" when we really mean diffracting planes and diffracted beams i.e., all the diffracted beams called ‘reflections’ because inside the bulk volume, there are planes so the x-rays get reflected from those planes (Let's make it more simple, every plane in the sample behave like a MIRROR........) Source: Book title: "Elements of X-RAY DIFFRACTION" by B. D. CULLITY