Hello.
Recently I have become interested in N, S -doped carbon material. In many publications, raman spectroscopy is used for characterization of the suggested materials. Especially the authors analyze G&D band, from the global vibrational mode.
However, I want to know "Are there any raman bands that indicate local vibration around Nitrogen doped site? If not, what is the reason? Because the local vibrational modes around N site is assymetric?"
As always, thank you for reading my question. I'm looking forward your answers.
What do you mean of local vibration? I think you must refer to the vibrations of the atoms nearby N,S atoms. Band should connect with the collective behaviors and is always related to a periodic long arrangement of the atoms, while non-periodic (random) local behavior only leads to localization. Therefore the local vibrations can only broaden or shift a characteristic Raman peak but probably can't give a local band! However, it is my opinion based on my limited knowledge, which, obviously, is not the true answer. So what you do, I think, is to do experiment and see if there are local bands! Caution: All the bands will break into many peaks for a limit sample if you use a vey expensive high-resolution Raman spectrometer. Good luck!
You can easily find literature about the use of Raman spectroscopy for doped carbon nanomaterials, especially for C nanotubes (e.g. Nguyen, Gaur, Shim, PRL98, 145504, 2007; Chan et al, PRL58, 1528, 1987) and for graphene (PRL 97, 266407, 2006). As there is a change of electron transfer per C atom due to doping, the frequency of phonon changes, and there is therefore a shift of the G band.
Alain
hello. I would like to know the meaning of negative Raman bands for a organic compound?
Thanks in advance
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