Photoassociation spectroscopy of the B [sup 1]Π state of LiCs

A first principles study of the spin–orbit coupling effect in LiM (M = Na, K, Rb, Cs) molecules

Both fully relativistic and scalar-state based perturbation models provided the spin–orbit functions of the LiM (M = Na, K, Rb, Cs) molecules at almost experimental level of confidence.

Long-range interactions between polar bialkali ground-state molecules in arbitrary vibrational levels

We have calculated the isotropic C6 coefficients characterizing the long-range van der Waals interaction between two identical heteronuclear alkali-metal diatomic molecules in the same arbitrary vibrational level of their ground electronic state X(1)Σ(+). We consider the ten species made up of (7)Li, (23)Na, (39)K, (87)Rb, and (133)Cs. Following our previous work [Lepers et al., Phys. Rev. A 88, 032709 (2013)], we use the sum-over-state formula inherent to the second-order perturbation theory, composed of the contributions from the transitions within the ground state levels, from the transition between ground-state and excited state levels, and from a crossed term. These calculations involve a combination of experimental and quantum-chemical data for potential energy curves and transition dipole moments. We also investigate the case where the two molecules are in different vibrational levels and we show that the Moelwyn-Hughes approximation is valid provided that it is applied for each of the three contributions to the sum-over-state formula. Our results are particularly relevant in the context of inelastic and reactive collisions between ultracold bialkali molecules in deeply bound or in Feshbach levels.

Experimental studies of the NaCs 5(3)Π0 and 1(a)3Σ+ states

We report high resolution measurements of 372 NaCs 5(3)Π(0)(v, J) ro-vibrational level energies in the range 0 ≤ v ≤ 22. The data have been used to construct NaCs 5(3)Π(0) potential energy curves using the Rydberg-Klein-Rees and inverted perturbation approximation methods. Bound-free 5(3)Π(0)(v, J) → 1(a)(3)Σ(+) emission has also been measured, and is used to determine the repulsive wall of the 1(a)(3)Σ(+) state and the 5(3)Π(0) → 1(a)(3)Σ(+) relative transition dipole moment function. Hyperfine structure in the 5(3)Π(0) state has not been observed in this experiment. This null result is explained using a simple vector coupling model.

High sensitive trap loss spectroscopic detection of the lowest vibrational levels of ultracold molecules

We present a controllable three-dimensional fluorescence modulation technique for the high sensitive trap loss detection of ultracold molecules. The lowest vibrational levels (v = 0 and 1) of the pure long-range state 0(-)(g) (6S(1/2) + 6P(3/2)) of a cesium molecule are detected directly with high rotational resolution. Our technique proved to be a robust tool for effectively improving the detection sensitivity of trap loss spectroscopy.

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%.