1. Exploring the excited states of the AsCl radical: A theoretical contribution.
- Author
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Yang, Ying, Zhang, Xiaomei, He, Wei, and Liu, Yufang
- Subjects
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EXCITED states , *DIPOLE moments , *POTENTIAL energy , *SPIN-orbit interactions , *RADICALS (Chemistry) , *DEUTERIUM - Abstract
Highlights • Total 34 Λ-S states of AsCl have been studied with the MRCI+Q method. • High-precision spectroscopic results are obtained from the calculated PECs. • The SOC effect makes 34 Λ-S states split into 74 Ω states. • The transition mechanism of a1Δ-X3Σ− and b1Σ+-X3Σ− has been detailedly analyzed. • The accurate lifetimes of a1Δ and b1Σ+ are determined. Abstract A manifold of electronic states for the AsCl radical are accurately characterized at the MRCI+Q level of theory. The potential energy curves (PECs) of 34 Λ-S states, correlated with three dissociation channels, have been constructed, and the spectroscopic constants of the bound Λ-S are determined. The calculated spectroscopic results well reproduce the measurement. A characteristic feature for AsCl is that the open-shell π2 configuration can give rise to the lowest three strongly bound states X3Σ−, a1Δ, and b1Σ+. The spin-orbit (SO) coupling is included using the state interacting method. The calculated SO matrix element indicates that strongly bound a1Δ and b1Σ+ states can be predissociated by A3Π. The SO coupling effect leads to total 74 Ω states. And the calculated energy splitting of X3Σ− amounts to 125 cm−1, in good agreement with the experimental value of 140 ± 8 cm−1. Both a1Δ and b1Σ+ have no SO coupling splitting, and their spectroscopic constants almost keep unchanged. Nevertheless, their dissociation energies D e are strongly decreased due to the avoided crossing. Transition mechanism of several important transitions for AsCl has been clearly expounded. Particularly, the nonzero transition dipole moments (TDMs) of transitions a1Δ-X3Σ− and b1Σ+-X3Σ− are borrowed from spin-allowed Λ-S transitions. Ultimately, the radiative lifetimes of a1Δ and b1Σ+ are determined to be 27.1 ms and 1.1 ms, respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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