IR band intensities of DC ₃N and HC ₃¹⁵N: Implication for observations of Titan's atmosphere

Abstract

We have obtained the infrared spectra and the corresponding absolute band intensities for two HC ₃N isotopomers: DC ₃N and HC ₃¹⁵N. Our results for DC ₃N are in good agreement with previous measurements except for the ν₂ and ν₃ stretching modes. For HC ₃¹⁵N, this study is the first including intensity measurements. We have also studied the possible detection of these isotopomers in Titan's atmosphere using the CIRS spectrograph onboard the Cassini spacecraft. Our simulation of the expected spectra shows that for a signal-to-noise ratio better than 100, the ¹⁵N isotopomer of HC ₃N could be detected. But, further study of HC ₃N hot bands are needed since some of them overlap the HC ₃¹⁵N Q-branch.