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][1] 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][2] or [oxygen][3]. 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? [1]: https://webbook.nist.gov/cgi/cbook.cgi?ID=C124389&Units=SI&Type=IR-SPEC&Index=1#IR-SPEC [2]: https://webbook.nist.gov/cgi/cbook.cgi?ID=C7727379&Mask=608 [3]: https://webbook.nist.gov/cgi/cbook.cgi?ID=C7782447&Mask=1000