HOT BANDS IN SYMMETRIC TOP SPECTRA PROPYNE AS A TEST CASE
Georges Graner · The Knowledge Bank (The Ohio State University) · 1989
In the recent years, we have studied at high resolution the spectrum of propyne (or methyl-acetylene) $CH_{3} C\\equiv CH$ in two spectral regions; the region $9-11 \\mu m$ which is dominated by the two fundamental bands $v_{5}(A_{1})$ and $v_{8} (E)$ and the region of the lowest fundamental band $v_{10}$ (E) at $30 \\mu m$. Since the $v_{10} = 1$ level is so low (Boltzmann factor equal to 0.21), hot bands originating from this level are often seen and, in several cases, their rotational structure can be assigned. Moreover, the fact that it is a E-type level, with the well-known Coriolis splitting and the $\\ell$-type doubling, produces unusual effects in these hot hands, especially for the subbands with $k``\\ell''=1$. Details will be given on the following hot bands, which being to five different types: $(v_{8} + v_{10})^{2} - V_{10}. (v_{8} + v_{10})0 - V_{10}. (v_{5} + v_{10})1 . V_{10}. (2v_{10})^{2} - V_{10}$ and $(2V_{10})^{0}-V_{10}$. These studies have led to a precise determination of the $A_{0}$ rotational constant of propyne.