Difference between X-ray Diffraction techniques and Raman spectroscopy

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Discussion Overview

The discussion revolves around the differences between X-ray Diffraction (XRD) and Raman spectroscopy as non-destructive techniques for determining the crystal structure of materials. Participants explore the principles behind each technique, their advantages and disadvantages, and the contexts in which one might be preferred over the other.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant notes that XRD operates on the principle of X-ray emission and Bragg's law, while Raman spectroscopy relies on Raman scattering.
  • Another participant suggests that X-rays interact with electrons and have a small wavelength, allowing them to reveal reciprocal space through diffraction, whereas Raman spectroscopy uses longer wavelengths to interact with atoms and reveal vibrational frequencies.
  • A participant expresses a desire for information on the limitations of XRD compared to Raman, speculating that XRD may only function at low temperatures while Raman operates at high temperatures.
  • It is mentioned that X-ray and neutron diffraction measure long-range order and are suited for determining crystal structures, while Raman spectroscopy measures excitations and may not provide complete crystal structure information.
  • One participant points out that obtaining vibrational excitation spectra from X-rays is possible but requires significant effort and specialized instruments.

Areas of Agreement / Disagreement

Participants express differing views on the capabilities and limitations of XRD and Raman spectroscopy, indicating that multiple competing perspectives remain without a consensus on which technique is superior or under what conditions one should be preferred over the other.

Contextual Notes

Participants mention various assumptions regarding temperature conditions for XRD and Raman, as well as the completeness of structural information obtainable from each technique, but these points remain unresolved.

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

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