IR Spectra: Why is CO2 a doublet at 2350cm-1?

by nbd
Tags: 2350cm1, doublet, spectra
nbd is offline
Jan27-13, 03:30 PM
P: 3
CO2 is supposed to create a "doublet" peak at 2350 cm-1 according to my IR correlation chart. Why is this doublet created? As DrDu explained in my previous post, two peaks are seen for the N-O bond because it has IR-active symmetric and asymmetric stretches. But CO2 is a linear molecule, and thus should not have an IR-active symmetric stretch.

I found another post on this forum in which chemistree explains the doublet as resulting from "symmetric and asymmetric" stretching, but that doesn't make sense to me considering the above. Does anyone know why the CO2 doublet exists? Thank you!
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DrDu is online now
Jan28-13, 01:59 AM
Sci Advisor
P: 3,370
That's the classical example of a "Fermi resonance".

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