Extended Fourier-transform spectroscopy studies and deperturbation analysis of the spin-orbit coupled A1Σ+ and b3Π states in RbCs

Abstract

The article presents a study of the strongly spin-orbit coupled singlet A(1)Σ(+) and triplet b(3)Π states of the RbCs molecule, which provide an efficient optical path to transfer ultracold molecules to their rovibrational ground state. Fourier-transform A(1)Σ(+) - b(3)Π → X(1)Σ(+) and (4)(1)Σ(+) → A(1)Σ(+) - b(3)Π laser-induced fluorescence (LIF) spectra were recorded for the natural mixture of the (85)Rb(133)Cs and (87)Rb(133)Cs isotopologues produced in a heat pipe oven. Overall 8730 rovibronic term values of A(1)Σ(+) and b(3)Π states were determined with an uncertainty of 0.01 cm(-1) in the energy range [9012, 14087] cm(-1), covering rotational quantum numbers J ∈ [6, 324]. An energy-based deperturbation analysis performed in the framework of the four A(1)Σ(+) - b(3)Π(Ω = 0, 1, 2) coupled-channels approach reproduces 97% of the experimental term values of both isotopologues with a standard deviation of 0.0036 cm(-1). The reliability of the deperturbed mass-invariant potentials and spin-orbit coupling functions of the interacting A(1)Σ(+) and b(3)Π states is additionally proved by a good reproduction of the A - b → X and (4)(1)Σ(+) → A - b relative intensity distributions. The achieved accuracy of the A - b complex description allowed us to use the latter to assign the observed (5)(1)Σ(+) → A - b and (3)(1)Π → A - b transitions. As is demonstrated, LIF to the A - b complex becomes as informative as to the ground X(1)Σ(+) state, which is confirmed by comparing the results of (4)(1)Σ(+) state analysis based on (4)(1)Σ(+) → A - b LIF with the data from V. Zuters et al. [Phys. Rev. A 87, 022504 (2013)] based on (4)(1)Σ(+) → X LIF.

Dynamic dipole polarizabilities of heteronuclear alkali dimers: optical response, trapping and control of ultracold molecules

“…We emphasize that table I is by no mean an exhaustive listing of spectroscopic studies on bialkali molecules. For example recent studies have been made on LiNa [73,92,[97][98][99][100], LiK [101], LiCs [102], NaK [103], NaRb [104], NaCs [105], KCs [106][107][108][109][110][111][112], RbCs [113][114][115]. However we show in following sections that a more precise de-TABLE I. References for all the electronic PECs used in the calculations (SOCME ≡ Spin-Orbit Coupling Matrix Elements).…”

Fourier-transform spectroscopy, direct potential fit, and electronic structure calculations on the entirely perturbed (4)1Πstate of RbCs

“…was determined from calculated term values E A∼b of the A 1 Σ + ∼ b 3 Π complex, which, according to Refs. [16,18],…”

“…In performing the experiments, a particular (4) 1 Π(v ′ , J ′ ) rovibronic level was reached via an intermediate level of fully mixed singlet-triplet A 1 Σ + ∼ b 3 Π complex, which has been comprehensively studied in Ref. [18]. This made it possible to predict with sufficient accuracy the required wave numbers of the first step of (4…”

Fourier-transform spectroscopy and relativistic electronic structure calculation on the $c^3Σ^+$ state of KCs

“…For Rb or Cs containing polar alkali diatomics a coupled-channels (CC) deperturbation analysis has been successfully applied to the A 1 Σ + and b 3 Π states fully mixed by a strong SO interaction. The 4x4 coupled-channels model yielded deperturbed potentials for both A and b states, as well as the on-diagonal and off-diagonal SO functions, which allowed one to reproduce thousands of rovibronic term values of the isolated singlet-triplet A − b complex with standard deviation of about 0.01 cm −1 , or even better, see [13] for NaRb, [14] for NaCs, [15][16][17] for KCs, [18,19] for RbCs, and [20] for KRb.…”