Question

Discuss the application of difraction in your field (Chemistry, Biology, Materials science ).

Are visible wavelength light sources useful there?

Can any light be used for diffraction? If not, why?

Answer 1

The main application of diffraction in material science is X-ray diffraction. It is a powerful technique to identify the crystal structure of different materials.
The criterion for diffraction is that,
n = 2d sin
For the first order diffraction, n= 1 and the wavelength must be of the same oder of d (comparable), which is the lattice spacing of crystals. But d-spacings for materials is in the angstrom range (10^-10 m). So x-rays are used, which have wavelength in the range of angstroms.
We can not use light since its wavelength is between 400 to 750 nm, which is too big for the d-spacings.