Electronic structure and spectra of the RbAr van der Waals system including spin-orbit interaction

Theoretical Modeling of Sr(q+) He (q = 0, 1, 2) van der Waals Systems Including Spin-Orbit Coupling

Using an ab initio methodology that incorporates pseudopotential technique in conjunction with pair potential approaches, core polarization potentials (CPP), large basis sets of Gaussian type, and full configuration interaction calculations, we investigate interaction of neutral and charged Srq+(q = 0,1,2) with helium atom. In this context, the core-core interaction of Sr2+-He is included using an accurately performed potential for the ground state at CCSD(T) level of calculation. Also, the potential energy curves and permanent and transition dipole moments of the ground state and numerous excited states have been performed respectively for Sr+He and SrHe systems. Subsequently, the spin-orbit effect is considered by utilizing a semiempirical method for states dissociating into Sr+(5p) + He, Sr+(6p) + He, Sr+(4d) + He, Sr+(5d) + He, Sr(5s5p) + He, and Sr(5s4d) + He. The spectroscopic constants of the Srq+(q = 0, 1, 2) He states, with and without spin-orbit interaction, are derived and assessed in comparison to the existing theoretical and experimental studies. Such comparison has revealed good agreement, especially, for the Sr+He ionic system. Additionally, the spin-orbit effect is considered for the X2Σ+ → 22Π1/2,3/2 and X2Σ+ → 32Σ1/2 + transition dipole moments for Sr+He.

Theoretical Investigation of the Electronic Structure and Spectra of Mg(2+)He and Mg(+)He

The ground and many excited states of the Mg(+)He van der Waals molecular system have been explored using a one-electron pseudopotential approach. In this approach, effective potentials are used to consider the Mg(2+) core and the electron-He effects. Furthermore, a core-core interaction is included. This has reduced the number of active electrons of the Mg(+)He, to be considered in the calculation, to a single valence electron. This has permitted to use extended Gaussian basis sets for Mg and He. Therefore, the potentianl energy and dipole moments calculations are carried out at the Hartree-Fock level of theory, and the spin-orbit effect is included using a semiclassical approach. The core-core interaction for the Mg(2+)He ground state is included using accurate CCSD(T) calculations. The spectroscopic constants of the Mg(+)He electronic states are extracted and compared with the existing theoretical works, where very good agreement is observed. Moreover, the transition dipole function has been determined for a large and dense grid of internuclear distances including the spin-orbit effect.

Kennard-Stepanov relation connecting absorption and emission spectra in an atomic gas

The Kennard-Stepanov relation describes a thermodynamic, Boltzmann-type scaling between the absorption and emission spectral profiles of an absorber, which applies in many liquid state dye solutions as well as in semiconductor systems. Here we examine absorption and emission spectra of rubidium atoms in a dense argon buffer gas environment. We demonstrate that the Kennard-Stepanov relation between absorption and emission spectra is well fulfilled in the collisionally broadened atomic gas system. Our experimental findings are supported by a simple theoretical model.