- #1
Scott Gray
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I've been doing IR spectroscopy to examine to the absorption spectrum of water and carbon dioxide, after which I took another absorption spectrum with a methane gas cell. The absorption spectrum without the methane shows absorption from carbon dioxide around 4000nm, however, this is not apparent on the spectrum with the methane which appears at a around . What else is it that contributes to the absorption in IR Spectroscopy?
Also why is it that the rotational line structure of Carbon Dioxide cannot be seen, does this have something to do with the moment of inertia of the carbon dioxide molecules?
Since carbon dioxide has no Q band (i.e. no transitions where the vibrational energy changes but the rotational energy doesn't) wouldn't it be expected that the wavelength at which it would occur if it happened to have one spike back up to match the observed intensity of the general curve? Since this doesn't happen there is some absorption resulting in a small spike but what else is absorbing this energy?
Thanks.
Also why is it that the rotational line structure of Carbon Dioxide cannot be seen, does this have something to do with the moment of inertia of the carbon dioxide molecules?
Since carbon dioxide has no Q band (i.e. no transitions where the vibrational energy changes but the rotational energy doesn't) wouldn't it be expected that the wavelength at which it would occur if it happened to have one spike back up to match the observed intensity of the general curve? Since this doesn't happen there is some absorption resulting in a small spike but what else is absorbing this energy?
Thanks.