Question

Briefly explain the difference between electron beam and laser diffraction.

Answer 1

The basic difference between the Electron beam and Laser diffraction can be derived based on what they are used for although both apply the same techniques of Diffraction grating.

So in an electron beam diffraction,accelerated electrons passes through a thin crystal, the crystal planes can act like a diffraction grating. (For a grating d sinθ = mλ-Braggs law.) Different crystal planes can produce different diffraction patterns. Planes that are spaced farther apart produce a narrower patterns.Now if we know the wavelength of the electron beam ,we can calculate the interplanar distance from Braggs law and thus we can calculate the interplanar symmetry as well using Electron beam diffraction.

While Laser diffraction measures particle size distributions by measuring the angular variation in intensity of light scattered as a laser beam passes through a dispersed particulate sample. Large particles scatter light at small angles relative to the laser beam and small particles scatter light at large angles. The angular scattering intensity data is then analyzed to calculate the size of the particles responsible for creating the scattering pattern, using the Mie theory of light scattering. The particle size is reported as a volume equivalent sphere diameter.

So the conclusion is Electron beam.measures the interplanar distance between the cystals while the Laser diffraction measures the size of the crystal or particle distribution. Electron beam uses Braggs law for the analysis while Laser Diffraction uses Mie theory of light scattering for particle size analysis.