Knowledge Bank

By using a tuneable diode laser and a tube oven operating at temperatures between $800\circ C$ and $1350\circ C$ the v = 1-0, 2-1, 3-2, and 4-3 transitions of $\mathrm{<mrow\; data-mjx-texclass="ORD">28</mrow>}Si16O$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">31</mrow>}P14N$ have been observed between $1210cm-1$ and $1320cm-1$. The $v=5-4$ transition has also been measured for $\mathrm{<mrow\; data-mjx-texclass="ORD">28</mrow>}Si16O$ and a few transitions due to the $\mathrm{<mrow\; data-mjx-texclass="ORD">29</mrow>}Si16O$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">30</mrow>}Si16O$ species have been measured. Some SiO v = 1 – 0 transitions have also been observed in a microwave discharge of $SiCl4$ and $N2O$. Combining these infrared measurements with microwave measurements made by others has led to an improved set of Dunham coefficients for describing the energy levels of these molecules. The SiO measurements are of particular interest to those who seek to understand the Inversion mechanism for the interstellar SiO maser. The results of attempts to measure other diatomic species will also be presented.