Knowledge Bank

The first spectroscopic observation of YbS has been made using visible laser absorption spectroscopy. The $A0+-X0+$ electronic transition of $\mathrm{<mrow\; data-mjx-texclass="ORD">172</mrow>}Yb32S,174Yb32S$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">176</mrow>}Yb32S$ has been recorded using the output of a Coherent 699-29 ring dye laser with selective detection of fluorescence. Spectra of the 0-0, 0-1, 1-1, 1-2, 2-2 and 2-3 bands were recorded with a measurement precision of approximately $0.003cm-1$, and from perturbations observed in the structure of the 2-2 and 2-3 bands, it was concluded that a level crossing occurs in the $A0+v=2$ level, In total, over 1500 line positions have been measured, assigned and employed in least-squares fits of the molecular parameters. The deperturbation and rotational analysis of the $A - $X system will be discussed.