Knowledge Bank

Spectral measurements have been made of a $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}C$ enriched sample of $CO2$ heated to 800K in a 1.75 m optical path absorption cell. The enriched sample consisted of 88% $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}C16O2$, 11% $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}C16O18O$, and 1% various other isotopes. The spectra were measured using the Geophysics Directorate high resolution Fourier transform spectrometer using a maximum optical path difference of 1.5 m resulting in an apodized resolution of $0.007cm-1$. Interferometric data were collected with sample pressures of 5 and 20 Torr. A different optical filter was used in the spectrometer during the measurement of the spectrum for each pressure. The 5 Torr spectrum was used to study the stronger bands found in the 580 to $850cm-1$ region and the 20 Torr spectrum was use for the weaker absorption bands in the 700 to $1070cm-1$ region. Rovibrational molecular constants were obtained from a weighted least squares fit to the observed line positions. The results of the line position analyses will be presented. This work was supported by the Air Force Office of Scientific Research (AFOSR) a& part of PL/GL Task 2310G1.