Electronic structure with spin-orbit coupling effect of HfH molecule for laser cooling investigations

The electronic structure, including the spin-orbit coupling effect of the HfH molecule, has been studied to determine if it can be cooled through Doppler and Sysphus laser cooling techniques. The multi-reference configuration interaction plus Davidson correction (MRCI + Q) method has been used to calculate its potential energy curves (P.E.C.s) in the Ω(±) and 2s+1Ʌ(+/-) representation. The spectroscopic constants Te, Re, ωe, Be, αe, the dipole moment µe, and the dissociation energies De agree very well with previously published work. In addition, we present in this work twenty new doublet and quartet states in the Ω(±) representation. The electronic transition dipole moment curves (TDMCs) between the lowest-lying electronic states have been investigated for the Δ - Π, Π - ∑+ and Δ - Φ transitions among specific Ω(±) states. The Franck-Condon factors (FCFs), the Einstein coefficient of spontaneous emission [Formula: see text] , and the radiative lifetime τ have been computed for the investigated transitions. In addition, properties of the molecules' electronic and vibrational states, such as the static dipole moment curves (D.M.C.s), the ionic character fionic, and the rovibrational constants are calculated. We deduce from our results that the HfH molecule is indeed a laser-cooling candidate that can reach a temperature as low as the nK regime. We present a complementary scheme with suitable experimental parameters. These results can be of great interest to experimental spectroscopists interested in ultracold diatomic molecules and their applications.

Laser Cooling and Electronic Structure of Be Halides Anions BeX- (X=Cl, Br, F, and I)

The adiabatic potential energy curves of the low lying electronic states of the Be halides anions BeX- (Cl, Br, F, and I) have been investigated in the representation 2s+1Ʌ(+/−) by using the complete active space self-consistent field (CASSCF) with multireference configuration interaction (MRCI+Q) method. The spectroscopic parameters Te,, Re, ωe, and Be, the static and transition dipole moment μe, and a rovibrational study of the investigated electronic states have been performed. New electronic states were investigated here for the first time. The highly diagonal FCF and the short radiative lifetime for the molecular anion BeF- prove its candidacy for direct Doppler laser cooling. The experimental proof of the stability and the calculated experimental parameters such as the vibrational branching ratio, the slowing distance, the recoil and Doppler temperatures with the experimental conditions of the buffer gas cell of this anion open the route for experimental work on the BeF- molecular ion.