The ground and low-lying excited states and feasibility of laser cooling for GaH+ and InH+ cations

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

“…44 Alternatively, one can exploit elements from group 1 (ns 1 configuration) to achieve the desirable molecular electronic structure. For example, molecular cations AH + (A = B, Al, Ga, In) were studied in the context of laser-cooling both experimentally and theoretically [31][32][33]40,98 . In particular, Odom and co-workers have demonstrated rotational cooling of trapped AlH + molecules to temperature of 3.8 K. 30 Below we revisit the electronic structure of AH + molecules using EOM-EA-CCSD and discuss the prospects of laser-cooling of an isoelectronic series of ALi + molecules with A = B, Al, and Ga. show that at the equilibrium geometry of AH + (A = B, Al, and Ga) the charge distribution in the ground X 2 Σ + state is mainly localized at atom A with Mulliken's charge varying in 0.89-1.01 range.…”

“…Our FCF estimations are consistent with previous studies. 32,40,98 Despite the diagonal FCFs of BH + and AlH + , challenges exist in efficient laser-cooling of these candidates [30][31][32][33] . In particular, continuous photon scattering may populate dissociative states either via the coupling of the A 2 Π state to a repulsive region of the ground X 2 Σ + state or by sequential absorption of the two photons.…”

“…Odom, Brown, and co-workers have explored optical cycling in AlH + , 30-32 BH + , 33 SiO + , 34,35 and TeH + , 36 often with an eye towards precision measurement. Other molecular ions have been studied theoretically including both cations [37][38][39][40] and anions [41][42][43] .…”

In Search of Molecular Ions for Optical Cycling: A Difficult Road

“…44 Alternatively, one can exploit elements from group 1 (ns 1 configuration) to achieve the desirable molecular electronic structure. For example, molecular cations AH + (A = B, Al, Ga, In) were studied in the context of laser-cooling both experimentally and theoretically [31][32][33]40,98 . Figure 6.…”

Optical Pumping of TeH+: Implications for the Search for Varying mp/me

“…The systematic uncertainties for reasonable experimental conditions are projected at the 1 × 10 −18 level or below. Furthermore, TeH + is one of a small, but growing class of molecular ions identified as having so-called diagonal Franck-Condon factors (FCFs), offering the possibility of rapid state preparation through broadband rotational cooling [15][16][17][18][19][20].…”