Rovibronic spectrum of PbS in 19520-22900 cm^-1

The rovibronic spectrum of PbS in the range of 19520-22900 cm-1 are investigated using the laser ablation-laser induced fluorescence method. The spectra in this range are assigned as the transitions of A-X and B-X according to the spectral analyzation. The upper electronic state of the transition in the range of 19520-22900 cm-1 is analyzed and discussed, and it is concluded that the upper state, A, is a mixture of 3Π0+ and 3ς0+- states, the 3Π0+ state is in domination. The spectrum in the range of 22025-22900 cm-1 is assigned as the B3Π1-X1ς+ transition. The molecular constants of these two transitions are derived from the observed spectra. The Frank-Condon factors (FCFs) of these two transitions are also calculated using the RKR/LEVEL method. All the results are compared with the reported theoretical and experimental results, showing that the A state is a mixing state which is in consistent with Balasubramanian's relativistic configuration interaction calculation result. And our calculated FCFs are in agreement with our recorded spectra.