The first spectroscopic observation of YbS: the A0+–X0+ visible laser excitation spectrum

The first spectroscopic observation of YbS has been made using visible laser excitation spectroscopy. Gas-phase YbS was produced in a Broida oven by the reaction of Yb metal vapour with either CS2 or OCS. Dispersed fluorescence spectra of an Ω=0–Ω=0 electronic transition were recorded with a CCD array detector. A least-squares fit of 34 band-heads leads to the following molecular parameters for the lower state: ωe″=365.6(2) cm−1 and ωe″xe″=1.14(2) cm−1. Determination of the parameters for the upper state of the transition was precluded by the irregular vibrational spacings, which increased with increasing v′.