Fourier-transform spectroscopy and global deperturbation treatment of the A1Σu+ and b3Πu states of K2 in the entire bound energy range.

Rotationally resolved Fourier-transform spectra of laser-induced fluorescence A1Σu+∼b3Πu→X1Σg+ of K2 molecules were recorded and analyzed, yielding 4053 term values of the spin-orbit (SO) coupled A ∼ b complex of the 39K2 isotopologue with ∼0.01 cm-1 accuracy. Their compilation with 1739 term values from previously published sources allowed them to cover the energy range [9955, 17 436] cm-1 from the bottom of the lower-lying b3Πu state up to the vicinity of the atomic asymptote 4s2S12 + 4p2P12, with a rotational quantum number J ∈ [0, 149].

Observation and modeling of bound-free transitions to the XΣ and aΣ states of KCs.

The oscillation continuum in laser-induced fluorescence spectra of bound-free cΣ → aΣ and (4)Σ → XΣ transitions of the KCs molecule was recorded by a Fourier-transform spectrometer and modeled under the adiabatic approximation. The required interatomic potentials for ground aΣ and XΣ states were reconstructed in an analytical Chebyshev-polynomial-expansion form in the framework of the regularization direct-potential-fit procedure based on the simultaneous consideration of experimental line positions from Ferber et al. [Phys.

Theoretical study of the Coriolis effect in LiNa, LiK, and LiRb molecules.

The non-adiabatic electronic matrix elements, LΠΣ(R), that arise from the spin-conserving electron-rotational interactions between all mΣ+ and mΠ states, where multiplicity m = 1, 3, converging to the lowest three dissociation limits of Li-containing alkali diatomics, LiM (M = Na, K, Rb), were calculated ab initio up to large internuclear distances, R. The required electronic wavefunctions were obtained within the framework of the multi-reference configuration interaction treatment of the two-valence-electron problem constructed using small-core scalar-relativistic effective core potentials and l-independent core-polarization potentials. A least squares analysis of the ab initio functions at large internuclear distances in conjunction with long-range perturbation theory (LRPT) revealed three different asymptotic behaviors of the LΠΣ(R → +∞)-functions: const.

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

The spin-orbit (SO) interactions in low-lying electronic states of the LiM (M = Na, K, Rb, Cs) molecular series are studied through ab initio calculations of potential energy curves and SO coupling matrix elements as functions of the interatomic distance, R. Two different approaches are employed: (a) the Fock-space relativistic coupled-cluster calculations (FS-RCC) which directly yield full relativistic energies, U(R); the SO coupling functions, ξ(R), are extracted a posteriori through projecting scalar-relativistic wave functions onto the subspaces spanned by their full-relativistic counterparts; (b) the evaluation of the scalar-relativistic electronic energies, U(R), and relevant ξ(R) functions using the configuration interaction method with core-valence correlation accounted for using core polarization potentials (CI-CPP). The SO-free potentials and SO coupling functions obtained within the framework of both approaches are in good agreement with each other and their prior theoretical and empirical counterparts.

Long-range behavior of the transition dipole moments of heteronuclear dimers XY (X, Y = Li, Na, K, Rb) based on ab initio calculations.

The ab initio electronic transition dipole moments (ETDMs) of heteronuclear dimers XY (X, Y = Li, Na, K, Rb) were calculated between the ground and excited states converging to the lowest three dissociation limits. The spin-allowed ETDMs were evaluated in a wide range of interatomic distances, R, by means of the quasi-relativistic electronic wave functions obtained by the multi-reference configuration interaction method. The inner-shell electrons (2 electrons for Li and Na atoms, and 10 and 28 for K and Rb, respectively) were described using the non-empirical shape-consistent effective core potentials.