Knowledge Bank

The three bending fundamentals of cyanoacetylene $(HC3N)$ have been recorded on the BOMEM FTS at the HIA/NRC in Ottawa with resolutions of $0.0025cm-1$ for $\nu 5(663cm-1)$ and $\nu 5(499cm-1)$ and $0.010cm-1$ for $\nu 7(222.5cm-1)$. The $\nu 5$ and $\nu 6$ bands have been observed in the Voyager/IRIS data$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ and were the motivation for this study. None of these bands had been recorded with high resolution methods previously although excellent excited state MW have been reported.2 The lowest fundamental had been seen only once before at low resolution $(0.6cm-1)$. The rotational structure for the fundamentals has been assigned and analyzed. Ground state constants in excellent agreement with the MW have been obtained confirming the assignments. Upper state constants have also been obtained for the fundamentals and will be reported. Assignment of the many hot and hot-hot bands is in progress along with diode laser measurements of individual line strengths. These will be utilized to complete the modelling effort needed for both simulating the infrared spectrum of the Titanian atmosphere and for the interpetation of ground based laser heterodyne experiments.