What additional information other than the phases present does the Raman spectroscopy generate that we could not get from XRD analysis?
I fully agree the Thomas,
but as far as you want to do training for Raman spectroscopy you should do that, since you know the results already by XRD.
Training is always necessary and meaningfull.
Of course, those methods are different and give you different information.
XRD - structural analysis, where you receive info about how atoms of molecules are packed in the crystalline structure.
Raman - analysis of thin structure electronic levels. Literally speaking, it tells you what kind on vibration modes you have in a sample.
For example, CNTs have non-informative XRD, whereas by Raman you may study change in various modes, detect attachment or detachment of smth to CNT etc. Vice versa, some crystals (various phases TiO2) have amazingly rich XRD, but also useful for Raman studies.
Hello All,
My opinion, it's better to do Raman Analysis to confirm your results.
Regards,
If your XRD data is clear about the material structure and the secondary phases ( if it is present), there is no need for Raman Analysis.
It's better to carry out a Raman Analysis to confirm your XRD results.
You can analyze the crystal structure with the use of XRD data and you can confirm the crystal structure by Raman spectra by using the location of vibration modes.
Another point: Raman is very surface sensitive, so gives you surface information not bulk information. XRD gives you "bulk" information and has a fairly high detection limit for secondary phases. So, if you are e.g. watching a reaction, XRD might not show you anything because the reaction product is just in a thin layer on the surface while the bulk is not yet affected. Raman would show you the reaction phase on the surface.
Remember, characterisation techniques are complementary, they use different mechanisms (spectroscopy vs diffraction, vibration modes vs crystal structure) and might also give you information from different parts of the sample. Better to use different techniques if available and confirm what you think you have or give yourself a headache trying to explain why wo results might superficially not agree.
Some times very small amount of impurity can not be detected with XRD in that case Raman is very helpful as it is sensitive to the small change of the bond length of the participating atoms.
XRD gives information about crystal structure of the sample while Raman spectroscopy can give you information about " site symmetry' of various " legands" present in your sample. I will suggest to record the Raman spectra; however, interpretation of the spectra may be harder compared to that of XRD
X-ray diffraction provides structural informations such as lattice parameters, Wyckoff positions, bond length etc. Raman spectroscopy also provides structural informations (indirectly), purity of the sample, amorphous nature, lattice dynamics etc. Since low Z elements are weak X-ray scatterers, in those cases Raman spectroscopy is a powerful tool to study such materials (Eg. Graphene, diamond etc). In many systems, if you combine Raman and XRD together, then you will get complete informations including structural aspect provided the system should be Raman active.
despite the confirmation of micro and lattice structure, an idea about polarizibilty is eviden which may be motivationa to further explore your material. so i think one must do it inspite of XRD if he wants to go ahead in the same problem
Dear Rohini. In my opinion, it to make or not Raman, it depend on what do you want to know. sometime structural changes it does not possible observe by XRD. In Raman is possible. For example, by Raman, is possible you to see defect at nanotube of carbon, in the XRD it isn't possible. but despite you have XRD, I think better you also make Raman.
Dear Rohini, As pointed out by Marcio Aurélio Pinheiro Almeida it is a question of what type of material you want to study is important. Whether it is Raman or XRD or SEM etc. You have to decide, depending upon the material, the type of study it needs. In a simpler sense XRD gives you information about what type of lattice and unit cell characteristics like cubic, tetragonal or orthorhombic etc. while the Raman spectroscopy tells you about the octahedral symmetry, tetrahedral symmetry and octahedral tilting of cages etc (In the case of Perovkite and ilemnite structures). If it is for learning if you have facilities available I would suggest you learn and master both.
Respected Prof. Karin Pruessner,
I am quite fascinated by the facts you stated for differentiating XRD from Raman spectroscopy analysis. I would be highly grateful to you if you could share any references for this point you highlighted that ''XRD has high detection limit for secondary phases compared to Raman''.
Thanks in advance.
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