Excited Electronic States of Sr: Ab Initio Predictions and Experimental Observation of the 2Σ State.

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, which we investigate theoretically up to 25000 cm above the ground state, to guide and explain new spectroscopic measurements. In particular, we focus on potential energy curves for the 1Σ, 2Σ, 1Π, 2Π, and 1Δ states computed using several variants of ab initio coupled-cluster and configuration-interaction methods to benchmark them.

On the 3Π state in caesium dimer.

Polarisation labelling spectroscopy technique was employed to study the 3Π state of Cs molecule. The main equlibrium constants are T=20684.56cm,ω=30.

Determination of the C(3)Σ state potential energy curve in KCs molecule based on polarisation labelling spectroscopy data.

The C(3)Σ state of KCs molecule was studied experimentally employing the polarisation labelling spectroscopy (PLS) technique. The experiment extended the prior knowledge of the state adding more than 40 vibrational levels to the previously existing data. A pointwise potential energy curve was constructed for the investigated state with the inverted perturbation approach (IPA) method, basing on experimentally determined energies of over 1300 rovibrational levels.

The RbSr Σ ground state investigated via spectroscopy of hot and ultracold molecules.

We report on spectroscopic studies of hot and ultracold RbSr molecules, and combine the results in an analysis that allows us to fit a potential energy curve (PEC) for the X(1)Σ ground state bridging the short-to-long-range domains. The ultracold RbSr molecules are created in a μK sample of Rb and Sr atoms and probed by two-colour photoassociation spectroscopy. The data yield the long-range dispersion coefficients C and C, along with the total number of supported bound levels.

Experimental investigation of electronic states of LiCs dissociating to Li(2(2)S) and Cs(5(2)D) atoms.

Polarization labeling spectroscopy technique was used to measure excitation spectra of LiCs molecule in the spectral range of 16,000-18,500 cm(-1). Four band systems were observed and assigned to transitions from the ground X(1)Σ(+) state to excited states (4)Ω = 0(+), (5)Ω = 0(+), (5)Ω = 1, and (6)Ω = 1 (in Hund's case (c) notation proper here), the latter three states being fine structure components of the states d(3)Π and e(3)Σ(+), nominally of triplet symmetry. The observed states are characterized spectroscopically and the experimental results are compared with predictions of theoretical calculations, showing accuracy of the theoretical electronic term values better than 100 cm(-1) and of the ω(e) and R(e) constants within 5%.