Did you think about following possibilities?

1) If you record pure MWCNT RA under the same conditions, these bands, e.g. from some aromatic C-H, C=C (or even from unwanted oxygen or sulphur containing groups) are not present? In the position ~2600 cm-1 vibration from S-H can be found. Do you work and handle under inert atmosphere or under air?

2) Under which conditions the MWCNTs/SnO2 composite was prepared? Is there some possibility of MWCNTs oxidation during this synthesis? Or contamination by sulphur?

3) SnO2 is very interesting (and therefore examined) material. See the links bellow if some of these effect is not responsible for your problems.

http://pubs.rsc.org/en/Content/ArticleLanding/2014/CP/C4CP00540F#!divAbstract

http://www.surface.tulane.edu/pdf/surface%20science%20of%20Tin%20Oxide.pdf

thanks a lot... sir

1. The triple carbon-cabon and carbon-nitrogen bonds have characteristic bands in this region. But they are usually narrow.

2. Always compare the sample spectra with substrate spectra. Try also to change excitation wavelengths (if possible) and compare results.

thanks sir..

Raman band occours in 3500-400 so it is good and use it