Theoretical study of low-lying electronic states of RhSi and IrSi

This study utilises the multi-reference configuration interaction method, incorporating scalar relativistic effects and spin-orbit coupling, to compute all low-lying electronic states of RhSi below 25,000cm−1 and IrSi below 30,000cm−1. The resulting potential energy curves, spectroscopic constants, and radiative lifetimes are presented and employed to assign the experimentally observed electronic states. The theoretical findings reveal that both RhSi and IrSi share the same ground states as their analogous monocarbides, X2Σ1/2+ for RhSi and X2Δ5/2 for IrSi, and feature quasi-triple bonds. These results offer valuable insights for future investigations into the electronic structures and spectroscopic properties of RhSi, IrSi, and related molecular systems.