Abstract
A molecular beam of PbS molecules was excited by a CW Ar+ laser in single and multimode operation. Fluorescence spectra induced by the 4880 AA line were recorded and four fluorescence series originating from the nu =7, 8 and 9 levels of the A0+ state were analysed. Using a pulsed dye laser, lifetimes of the nu =4, 5, 6, 7 and 8 level of the A0+ state, the nu =0, 1, 2 and 3 levels of the B1 state and the nu =21 level of the a1 state were measured. The electronic transition moments of the a-X, A-X and B-X transitions were calculated and the lifetimes of the a, A and B states of PbS are compared with those of PbO.