Difference between X-ray Diffraction techniques and Raman spectroscopy

[ralden]

Hi everyone, I'm little bit confuse about non destructive techniques such as XRD (X-ray Diffraction) and Raman spectroscopy, I know that both techniques can determine the crystal structure of the certain materials, and also, I know that XRD is working with the principle of emission of x-ray and Bragg's law while Raman spectroscopy is the Raman Scattering (Honestly i don't know much about this techniques), so when my professor ask me, "why you don't use Raman instead of XRD?" so besides of my professor's question my question is what is/are the disadvantage/s and advantage/s of using Raman over XRD?. thank you.

 

[hokhani]

I think x ray interact with electrons and with small wavelenght (large wave vector) can reveal the reciprocal space by diffraction while Raman spectroscopy uses radiation with long wavelenght (low energy) which interacts with atoms, molecules or ions and can reveal the vibration frequencies of system by scattering.

 

[ralden]

yes you are right, but I'm expecting of a kind of an answers regarding the limitation of using xrd over the raman. (for example xrd only operates/function in a low temperature while raman only operate/function in high temp, but it's just a guess).

 

[M Quack]

X-ray or (elastic) neutron diffraction measure long range order of the ground state and are therefore very well suited to determining crystal structures.

Raman spectroscopy measures excitations.

These are really quite different things. Selection rules of allowed and forbidden Raman transitions may help in determining the crystal symmetry (space group), but I don't know if you can get the complete crystal structure from Raman.

Unless you go to very significant efforts you cannot get vibrational excitation spectra from x-rays. It is possible, but there are only a hand full of instruments on the planet that can do that.