Knowledge Bank

We have recently determined the molecular constants of propyne ($CH3C=CH$) in its ground vibrational state and in its low lying excited states $(\nu 10=1;2$ and $\nu a=1)$. We are now studying the next states which ly between 900 and $1100cm-1$. This polyad includes the levels: $\nu 5=1,\nu 8=1,\nu 9=\nu 10=1$ and $\nu 10=3$. The rotational spectra of these states were measured up to 470 GHz. $\nu 5\nu 8$ and a part of $(\nu 9+\nu 10)0$ bands were analyzed at $10\mu$m. But most of the information concerning $\nu 9=\nu 10=I$ was found by studying the hot bands $(\nu 9+\nu 10)2-\nu 10$ and $(\nu 9+\nu 10)0-\nu 10$ on diode laser spectra at $16\mu$m. The information on the $\nu 10=3$ levels was obtained from the hot bands at $30\mu$m on a Fourier transform spectrum. A global fit of the upper state energies and rotational frequencies gives the molecular parameters.