A theoretical contribution to the characterization of the electronic structure and spectroscopic properties of the low-lying states of strontium monoiodide, SrI

A high-level theoretical approach - SA-CASSCF/MRCI - is used to explore the electronic structure and spectroscopic properties of a manifold of low-lying electronic states of the radical strontium monoiodide, SrI. For both Lambda + S and Omega representations, potential energy curves are constructed, and the associated spectroscopic parameters derived. Dipole moment functions and vibrationally averaged dipole moments allow one to quantify the polarity of the various states. With the transition dipole moment functions, Einstein A(v'v'') coefficients for spontaneous emission were computed for pairs of selected states and radiative lifetimes evaluated for the low-lying vibrational levels of the excited electronic states. Reliable results are also provided for the yet unknown states A' (2)Delta and E (2)Sigma(+) which can guide spectroscopists to their experimental detection. Combined with recent theoretical work on SrF, SrCl, and SrBr one now can have a broad perspective of the trends in spectroscopic properties of this series of halides. (C) 2021 Published by Elsevier Ltd.