Accurate spectroscopic properties of 19 low-lying states of PCl radical including the electronic transition properties

Abstract

The spectroscopic properties are in detail studied for the 11Σ−, 21Σ−, b1Σ+, c1Π, 21Π, 31Π, a1Δ, 21Δ, X3Σ−, C3Σ−, 33Σ−, 13Σ+, A3Π, B3Π, 33Π, 13Δ, 23Δ, 15Σ− and 15Π states, which are yielded from the first two dissociation limits, P(4Su)+Cl(2Pu) and P(2Du)+Cl(2Pu), of the PCl radical. Of the nineteen states, the 33Σ−, 13Σ+, 13Δ, 23Δ and 15Π states are the repulsive ones. The 21Σ−, 21Δ and 15Σ− states and the second well of A3Π state are very weakly-bound ones. The A3Π and B3Π states, the B3Π and 33Π states, and the 21Π and 31Π states have the avoided crossings. The A3Π state is found to possess the double well. The potential energy curves (PECs) are calculated with the CASSCF method followed by the internally contracted MRCI approach with Davidson correction together with the Dunning’s correlation-consistent basis sets, aug-cc-pV6Z. To improve the quality of PECs, core–valence correlation and scalar relativistic correction calculations are included simultaneously. The PECs are extrapolated to the complete basis set limit. The vibrational properties are evaluated for several weakly-bound states. The spectroscopic parameters are determined, and compared with those available in the literature. The Franck–Condon factors and radiative lifetimes of the transitions from the A3Π, B3Π and 33Π states to the X3Σ− state and from the c1Π, 21Π and 31Π states to the a1Δ state are calculated for several low vibrational states. And some necessary discussion is performed. Analyses demonstrate that the spectroscopic properties of PCl radical reported in this paper can be expected to be reliably predicted ones.