High accuracy theoretical investigations of CaF, SrF, and BaF and implications for laser-cooling

Yongliang Hao, L. F. Pasteka, Lucas Visscher, Parul Aggarwal, Rick Bethlem, Alexander Boeschoten, Anastasia Borschevsky*, Malika Denis, Kevin Esajas, Steven Hoekstra, Klaus-Peter Jungmann, Virginia Marshall, Thomas Meijknecht, Maarten Mooij, Robertus Timmermans, Anno Touwen, W. Ubachs, Lorenz Willmann, Yanning Yin, Artem Zapara

*Bijbehorende auteur voor dit werk

OnderzoeksoutputAcademicpeer review

23 Citaten (Scopus)
150 Downloads (Pure)

Samenvatting

The NL-eEDM collaboration is building an experimental setup to search for the permanent electric dipole moment of the electron in a slow beam of cold barium fluoride molecules [NL-eEDM Collaboration, Eur. Phys. J. D 72, 197 (2018)]. Knowledge of the molecular properties of BaF is thus needed to plan the measurements and, in particular, to determine the optimal laser-cooling scheme. Accurate and reliable theoretical predictions of these properties require the incorporation of both high-order correlation and relativistic effects in the calculations. In this work, theoretical investigations of the ground and lowest excited states of BaF and its lighter homologs, CaF and SrF, are carried out in the framework of the relativistic Fock-space coupled cluster and multireference configuration interaction methods. Using the calculated molecular properties, we determine the Franck-Condon factors (FCFs) for the A2Π1/2→X2Σ+1/2 transition, which was successfully used for cooling CaF and SrF and is now considered for BaF. For all three species, the FCFs are found to be highly diagonal. Calculations are also performed for the B2Σ+1/2→X2Σ+1/2 transition recently exploited for laser-cooling of CaF; it is shown that this transition is not suitable for laser-cooling of BaF, due to the nondiagonal nature of the FCFs in this system. Special attention is given to the properties of the A′2Δ state, which in the case of BaF causes a leak channel, in contrast to CaF and SrF species where this state is energetically above the excited states used in laser-cooling. We also present the dipole moments of the ground and excited states of the three molecules and the transition dipole moments (TDMs) between the different states. Finally, using the calculated FCFs and TDMs, we determine that the A2Π1/2→X2Σ+1/2 transition is suitable for transverse cooling in BaF.
Originele taal-2English
Artikelnummer034302
Aantal pagina's17
TijdschriftJournal of Chemical Physics
Volume151
Nummer van het tijdschrift3
DOI's
StatusPublished - 15-jul-2019

Citeer dit