High-resolution laser spectroscopy of YbS: Deperturbation analysis of the A0+–X0+ transition

The A0+–X0+ electronic transition of Yb172S32, Yb174S32, and Yb176S32 has been rotationally analyzed for the first time. Doppler-limited laser excitation spectroscopy with selective detection of fluorescence was used to obtain spectra of the 0–0, 0–1, 1–1, 1–2, 2–2, and 2–3 bands with a measurement precision of approximately 0.003 cm−1. The 2–2 and 2–3 bands were found to be perturbed by a level crossing that occurs in the A0+ υ=2 level. In total, over 1500 line positions have been measured, assigned, and employed in least-squares fits of molecular parameters. The principal deperturbed results for the X0+ state, which arises primarily from the Yb2+(4f14)S2− electronic configuration, are Re=2.3591(2) Å and ωe(174YbS)=366.714(2) cm−1, and for the A0+ state, R0(174YbS)=2.3905(2) Å.