Knowledge Bank

By using microwave discharges, D.C. discharges, or a high temperature oven, we have been able to measure the $v=1\leftarrow 0$ absorption spectra of C10, BC1, Sn0, and A1F and the $\nu =2$ $\leftarrow 1$, $3\leftarrow 2$, and $4\leftarrow 3$ transitions in the latter three molecule. The measurements include transitions due to the two chlorine isotopes, the two boron isotopes, and the eight most abundant tin isotopes. For each molecular species a set of Dunham coefficients is determined that is able to fit the infrared and microwave data for all isotopic species within experimental error. C10 has been measured by other workers but the present measurements are more accurate and allow one to calculate the important transitions with an uncertainty of $\pm 0.0002$ $cm-1$.