Excited electronic states of Sr${}_2$: ab initio predictions and experimental observation of the $2^1{\Sigma }_u^{+}$ state

Abstract

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 Sr${}_2$, which we investigate theoretically up to 25000 cm${}^{-1}$ above the ground state, to guide and explain new spectroscopic measurements. In particular, we focus on potential energy curves for the $1^1{\Sigma }_u^{+}$, $2^1{\Sigma }_u^{+}$, $1^1{\Pi }_u$, $2^1{\Pi }_u$, and $1^1{\Delta }_u$ states computed using several variants of advanced \textit{ab initio} methods to benchmark them. In addition, a new experimental study of the excited $2^1{\Sigma }_u^{+}$ state using polarisation labelling 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.

arXiv comment11 pages, 5 figures

References in corpus (20)

• Search for New Physics with Atoms and Molecules
• Cold and Ultracold Molecules: Science, Technology, and Applications
• Production of cold molecules via magnetically tunable Feshbach resonances
• Cold molecules: Progress in Quantum Engineering of Chemistry and Quantum Matter
• Precision Test of Mass Ratio Variations with Lattice-Confined Ultracold Molecules
• Precise study of asymptotic physics with subradiant ultracold molecules
• Molecular lattice clock with long vibrational coherence
• Interatomic potentials, electric properties, and spectroscopy of the ground and excited states of the Rb_2 molecule: Ab initio calculations and effect of a non-resonant field
• Photodissociation of ultracold diatomic strontium molecules with quantum state control
• The ^1S+^1S asymptote of Sr_2 studied by Fourier-transform spectroscopy
• Rovibrational dynamics of the strontium molecule in the A^1Σ_u^+, c^3Π_u, and a^3Σ_u^+ manifold from state-of-the-art ab initio calculations
• Fourier-transform spectroscopy of Sr2 and revised ground state potential
• Prospects for application of ultracold Sr${}_2$ molecules in precision measurements
• Formation of ultracold SrYb molecules in an optical lattice by photoassociation spectroscopy: theoretical prospects
• A terahertz vibrational molecular clock with systematic uncertainty at the $10^{-14}$ level
• The RbSr ${}^2{\Sigma }^{+}$ ground state investigated via spectroscopy of hot & ultracold molecules
• Quantum phases of quadrupolar Fermi gases in optical lattices
• Ultracold ${}^{88}{\mathrm{Sr}}_2$ molecules in the absolute ground state
• The states 1^1Σ^+_u, 1^1Π_u and 2^1Σ^+_u of Sr_2 studied by Fourier-transform spectroscopy
• Ab initio electronic structure of the Sr${}_2^{+}$ molecular ion

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