Despite its apparently simple nature with four valence
electrons,
the strontium dimer constitutes a challenge for modern electronic
structure theory. Here we focus on excited electronic states of Sr2, which we investigate theoretically up to 25000 cm–1above the ground state, to guide and explain new spectroscopic measurements.
In particular, we focus on potential energy curves for the 11Σu+, 21Σu+, 11Πu, 21Πu, and 11Δustates computed using several variants of ab initio coupled-cluster
and configuration-interaction methods to benchmark them. In addition,
a new experimental study of the excited 21Σu+state using polarization labeling spectroscopy is presented, which
extends knowledge of this state to high vibrational levels, where
perturbation by higher electronic states is observed. The available
experimental observations are compared with the theoretical predictions
and help to assess the accuracy and limitations of employed theoretical
models. The present results pave the way for future more accurate
theoretical and experimental spectroscopic studies.