Knowledge Bank

We obtained 40 absolute line wavenumbers in the $3\nu 3$ band of $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}C16O2$ between 6927 and $6989cm-1$ and more than 600 absolute line wavenumbers in the near infrared absorption spectrum of $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}C2H2$ between 7060 and $9900cm-1$ using high-resolution Fourier transform spectroscopy. The calibration of the $CO2$ line wavenumbers relied on heterodyne frequencies available in the $\nu 1+\nu 3$ band of $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}C2H2$ near $6556cm-1$. We have calibrated the acetylene spectra using heterodyne frequencies available in the 2 - 0 band of $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}C16O$ and the line wavenumbers obtained in the $ev3$ band of $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}C16O2$. Comparison with absolute line wavenumbers obtained independently at JPL in the $3\nu 3$ band of $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}C2H2$ near $9649cm-1$, calibrated using absolute wavenumbers available in the 2 - 0 and 3 - 0 (near $6350cm-1$) bands of $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}C16O$, shows good agreement. Finally, we have also determined vibration-rotation constants for the observed upper vibrational states of $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}C2H2$, without accounting for the perturbations affecting these states however.