Yes, apparently it is true what Mr. Anatoly just said. It belongs to the adsorption doublet band. But I would suggest one more thing as well for your understanding and better training. You can find the literature regarding the IR spectra of Ceria nanoparticles as a lot of research has been done in this. From there, you can easily compare. This will be very good for your future research. I hope I made myself clear. And don't mind the way I answered your question as I only intend to help you how to do it in future :)