Electronic Structure and Spectra of the RbAr van der Waals System Including Spin–Orbit Interaction

Abstract

The potential energy curves and spectroscopic constants of the ground and excited states of the RbAr van der Waals system have been determined using a one-electron pseudopotential approach. This technique is used to replace the effect of the Rb(+) core and the electron-Ar interactions by effective potentials. The core-core interaction for Rb(+)Ar was incorporated using the accurate CCSD(T) potential of Hickling et al. [Hickling, H. L.; Viehland, L. A.; Shepherd, D. T.; Soldán, P.; Lee, E. P. F.; Wright, T. G. Phys. Chem. Chem. Phys. 2004, 6, 4233-4239]. This model reduces the number of active electrons of the RbAr van der Waals systems to just the single valence electron, permitting the use of very large basis sets for the Rb and Ar atoms. Using this approach, the potential energy curves of the ground and excited states dissociating into Rb(5s, 5p, 4d, 6s, 6p, 6d, and 7s) + Ar are calculated at the SCF level. Spin-orbit interaction was also considered within a semiempirical scheme for the states dissociating into Rb(5p) and Rb(6p). Spectroscopic constants are derived and compared with the available theoretical and experimental data. Such comparisons for RbAr show very good agreement for the ground and the first excited states. Furthermore, we have predicted the B(2)Σ(+)(1/2) ← X(2)Σ(+), A(2)Π(1/2) ← X(2)Σ(+), A(2)Π(3/2) ← X(2)Σ(+), A(2)Π(3/2) ← X(2)Σ(+), 5(2)Σ(+) ← X(2)Σ(+), 3(2)Π(1/2) ← X(2)Σ(+), and 3(2)Π(3/2) ← X(2)Σ(+) absorption spectra.

Kennard-Stepanov Relation Connecting Absorption and Emission Spectra in an Atomic Gas

“…(11) The lineshapes presented in this paper, as shown in Fig. 1(b), were computed by using the theoretical ab initio Rb-Ar interaction potentials from [17]. Note that ∆U (r) and ρ e,g (r) are spherically symmetric in the case of the 5 2 S 1/2 and 5 2 P 1/2 states of Rb (X 2 Σ 1/2 and A 2 Π 1/2 potential curves) and are anisotropic for the 5 2 P 3/2 state of Rb, for which A 2 Π 3/2 and B 2 Σ 1/2 potential curves describe Rb-Ar interaction along two orthogonal directions.…”

“…We thank H. Berriche for providing numerical data of rubidium-argon interaction potentials [17]. Financial support from the DFG (We 1785/15) and the ERC (IN-PEC) is acknowledged.…”

“…1(a) gives calculated quasistatic rubidium-argon molecular potential curves, as derived by ab-initio methods in Ref. [17]. For large interatomic distance, the shown curves asymptotically approach the energy of rubidium atoms in the 5S 1/2 , 5P 1/2 , and 5P 3/2 electronic states.…”

“…(color online) (a) Theoretical rubidium-argon interaction potentials[17], as relevant for collisional broadening of the rubidium D-lines. (b) Calculated fluorescence (solid red line) and absorption (dashed blue line) spectra of rubidium atoms perturbed by collisions with argon buffer gas atoms.…”

Laser refrigeration of gas filled hollow-core fibres

“…Numerical illustration -We focus our numerical analysis to the Rb-Ar exciplex [24][25][26], for which experimental results indicating cooling have been shown in Refs. [16,17].…”