Good day,
I have a Raman spectra for 4 samples including Graphene oxide (GO) and its nanocomposites. According to the attached figure can sb tell me whether the different peak positions of the four samples are attributed to the uncertainty or the peak shift?
Thanks.
These are the D (1350) and G modes (15xx). You can easily find plenty of literature on these characteristic bands which I highly recommend you to read if you want to advance working with graphene derivatives. Long story short: higher D -> many defects, higher G -> larger intact domains.
Regarding your question: no, a shift of the G-mode as large as this is definitely not within the uncertainty. The G-mode is, among other things, sensitive towards deformations and twisting, so you can say that the deformation geometry in the red and black line are similar, while green and blue may be deformed differently.
Hi!
As your base sample (functionalized graphene) contains sp^2 hybridized carbon, you are getting a modified G mode at ~1570 cm ^{-1}. In addition, you are getting a D mode for defects in the system. The ratio between G anad D mide gives you the idea about "degree/concentration of defects".
For the graphene family, D and G band positions are not only known, but also their shifts as a function of defect-density, temperature, pressure etc are well-cultivated. From your data, the shifts for the G-band is quite clear.
Regarding the error or standard-deviation that you are doubtful about, you can easily know this information from the instrumental details. I use a Raman spectrometer with two gratings: 600 grooves/mm (Deviation~ 3 - 4.5 cm^-1) and 1800 grooves/mm (Deviation~ 1 - 1.5 cm^-1). Only lower shifts than these specified values are because of instrumental limitation or uncertainty.
In general, a shift in Raman peak position could be attributed to various reasons such as size effect (going from bulk to nano), pressure, temperature, doping, strain etc
I also agree with Jürgen Weippert and Souvik Bhattacharjee. The significant shift in the G band is no uncertainty. But, the shift in the D band is most likely an uncertainty which further depends on the spectral resolution of Instrument, still change in its intensity is also informative. You can find a lot of papers in this context.
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