Spectroscopy and rovibrational cooling of AuF and its cation

The feasibility of laser cooling of AuF molecule and its cation are investigated from vibrational and rotational perspectives. The spectroscopy of AuF molecule and AuF⁺ molecular cation are obtained by the method of multireference configuration interaction plus Davidson correction (MRCI + Q) and spin-orbit coupling (SOC) effect. On account of the accurate molecular spectroscopy and the transition dipole moment, the Franck-Condon factors and radiative lifetimes of AuF molecule and AuF⁺ molecular cation are calculated. Comparing the criterias of laser cooling candidate molecules, the AuF is an excellent candidate for laser cooling and while AuF⁺ is not sutable. The b³Π₀₊ ↔ Χ¹Σ⁺₀₊ transition of AuF is selected for laser cooling and an optical cycling scheme is proposed. The scheme possesses highly diagonally Franck-Condon factors and the scattered photons achieve ∼ 10⁴. Furthermore, the rotational transition analysis is also included in our work and found that its Franck Condon factors and Einstein coefficients are undistorted. Our work could provide theoretical support and accelerate the laser cooling of AuF molecules in experiments.

Spectroscopy and laser cooling of SiBr+: A computational perspective

In the previous work, the SiBr⁺ cation is suggested as a candidate molecule for laser cooling, and in this work, on the basis of high-level ab initio calculation, the possibility of SiBr⁺ cation laser cooling is studied by considering the core-valence electrons correlations and spin-orbit coupling (SOC) effect. The potential energy curves of 12 Λ-S states and 36 Ω states considering SOC were obtained by using the multi-reference configuration interaction method and Davidson correction. Our computed results show that the Franck-Condon factor f₀₀ for SiBr⁺ is only 0.619, which cannot guarantee that the number of the leaked photons is enough small, and more pumping laser beams are needed. Based on the calculated molecular properties, we discuss in detail the feasibility of laser cooling of SiBr⁺ and the results indicate that it is a challenge for laser cooling of SiBr⁺ .

Characterization of the low-lying electronic states of tin monohydride cation including the spin-orbit coupling effect: A theoretical perspective

High-level ab initio computations have been performed on SnH⁺. The potential energy curves and spectroscopic constants of the low-lying Λ-S electronic states, as well as their associated Ω states, are derived at the icMRCI + Q level employing basis sets of quintuple-ζ quality. The transition dipole moments, Einstein coefficients, radiative lifetimes and Franck-Condon factors of three spin-forbidden transition bands ( [Formula: see text] , [Formula: see text] and [Formula: see text] ) are determined. Comparisons between our predictions and available experimental results indicate reasonable agreement. The spin-orbit coupling effect has been proved to affect these low-lying electronic states significantly.

The study of laser cooling of TeH- anion in theoretical approach

The probabilities of laser cooling of TeH^- anion via a spin-forbidden transition and a three-electronic-level transition are proposed. The potential energy curves of the X¹Σ⁺, a³∏, A¹∏, and b³Σ⁺ electronic states of tellurium monohydride anion (TeH^-) are calculated using multi-reference configuration interaction method. Davidson corrections, core-valence correlations and spin-orbit coupling effects are also considered. The AWCV5Z-PP pseudopotential basis set of Te atom is used. Spectroscopic parameters of the Λ-S and Ω states are obtained by solving radial Schrodinger equation. These results are reported at the first time. Permanent dipole moments of the Ω states and transition dipole moments of the a₂1↔X0⁺ and A1↔X0⁺ transitions are also calculated. Highly diagonally distributed Franck-Condon factors of the a₂1↔X0⁺ and A1↔X0⁺ transitions are obtained, the value of f₀₀ is 0.9970 and 0.9980, respectively. Spontaneous radiative lifetimes of the a₂1 and A1 excited states are predicted. i.e. τ(a₂1) = 200.3 ns and τ(A1) = 84.3 ns. Only the main pump laser is required to driving a₂1↔X0⁺ and A1↔X0⁺ transitions. The laser wavelengths both are in the visible region. Doppler temperatures and recoil temperatures of laser cooling TeH^- anion are also predicted.

In search of molecular ions for optical cycling: a difficult road

Optical cycling, a continuous photon scattering off atoms or molecules, is the key tool in quantum information science.