3
$\begingroup$

I am new to spectroscopy, so I am not sure how my questions are perceived. I just want to make sure that I am not lost, so any kind of suggestion is welcome.

I am interested in the infrared absorption spectrum of molecular nitrogen and oxygen. I thought it would be more streamlined to obtain this information, but it is not easy as I thought.

What I did is, I went to the HITRAN database and downloaded the line strengths of both $\ce{N2}$ and $\ce{O2}$, and I extracted the $\texttt{.par}$ file, and I am able to see some obvious peaks.

I also have a range of interest for both temperature (~70-300 K) and pressure (~300-3000 Pa), but I don't know where to start.

Another point of confusion for me is as follows: On the NIST page for $\ce{CO2}$, the is a section titled "IR spectrum", which clearly shows absorption/emissions spectrum of $\ce{CO2}$. However, such a section does not exist for nitrogen or oxygen. Why is there no section for this?

How do I go about finding absorption spectrum for $\ce{N2}$ and $\ce{O2}$ in my range of interest? Should I simply google keywords and try to see if I can find what I find on Google image search?

Improve this question
$\endgroup$
3

1 Answer 1

Reset to default
7
$\begingroup$

There is a good reason for not being able to find the mid-IR absorption spectra of nitrogen and oxygen. Their vibrations are infrared inactive. Infrared absorption peaks are observed when there is a change in the dipole moment during a vibration. In such cases, one can resort to rotational-vibrational Raman spectroscopy to get molecular information.

Oxygen does absorb near the deep-red visible region (liquid oxygen is light blue). One can see such absorption bands in the solar spectrum.

Improve this answer
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.