Raman spectroscopy is a commonly used optical and mostly non-invasive research method, for example for chemical analysis or in solid state physics. Similarly X-ray photoelectron spectroscopy (XPS) is a quantitative spectroscopic technique that measures the elemental composition, empirical formula, chemical state and electronic state of the elements that exist within a material.
I am trying to know distinguishing features between XPS and Raman spectroscopy - if anyone has some ideas, or references regarding this, please share.
In addition to Larry's comment I send you detail information about Raman scattering and XPS techniques, where are also presented the physics of these different processes.
XPS probes core and valence levels of an atom, while Raman probes chemical bonds. Thus XPS peaks can be used to determine stoichiometry of a material. Shifts in those peaks contain information about chemical state of atoms. I just read a paper on Raman spectroscopic characterization of the different forms of amorphous carbon, which highlights nicely the information that technique can provide, beyond XPS, when looking to characterize materials. Reading something along those lines would help you. Reference: Chu and Li, Materials and Chemical Physics 96 (2005), p.253
In addition to Larry's comment I send you detail information about Raman scattering and XPS techniques, where are also presented the physics of these different processes.
The Raman spectroscopy allows you to characterise your sample from a "crystalline structure" point of view. The laser beam (that is photons) impinging on the sample is modulated by the phonons (or dually waves) which are the fingerprints of the lattice structure of the sample (the principle is the same as the solar light reflected by a pool full of water on a wall: the light is modulated by the waves which ripple the surface of the pool). This method works really well if you are interest in structure changes or transitions. It is essentially a surface method.
I do not know really well the XPS, but it essentally allows you a chemical analysis of your samples using electron emitted by photoelectric effect and Auger electrons.
Some general reference on Raman:
- C. Kittel, “Introduction to Solid State Physics”, J. Wiley and Sons, New York 1996 (7th Edition), Chapter 4
- J. H. Parker, Jr., D. W. Feldman, and M. Ashkin, Phys. Rev., 155 (1967), 712
An example of a Raman study on UO2 is attached
Good answer Andrea. As you rightly pointed out, Raman Spectroscopy is the best tool for the analysis of the local environment of the crystal structure. It is used when it is needed to probe the local structure, which accurately gives the information especially when the material exhibits polymorphism.Since XRD gives only the global/average structure, Raman Spectroscopy tool can be utilized to establish the local structure further.
I dont know much about XPS.
Thank you every one. I have to study to give my view. actually I am new in Material Characterization. Thank you once again
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