Knowledge Bank

A tunable diode laser has been used to mesure the spectra of a number of molecules that are difficult to observe in the gas phase at room temperature. Measurements have been made on KF, LiF, SnO, PbS, and other species that absorb between $828cm-1$ and $880cm-1$. Temperatures between 1000 k and 1425k were used. Either $\Delta v=1$ or $\Delta v=2$ transitions were observed, depending on the match between the molecular vibrational frequency and the available diode laser element. The spectra were fit directly to a Dunham potential function by means of a non-linear least-squares program. A single potential function with a mass dependent $Be$ and $we$ has been used to fit the spectra for several isotopic species.