Proposal for Laser Cooling of Complex Polyatomic Molecules

Abstract

An experimentally feasible strategy for direct laser cooling of polyatomic molecules with six or more atoms is presented. Our approach relies on the attachment of a metal atom to a complex molecule, where it acts as an active photon cycling site. We describe a laser cooling scheme for alkaline earth monoalkoxide free radicals taking advantage of the phase space compression of a cryogenic buffer-gas beam. Possible applications are presented including laser cooling of chiral molecules and slowing of molecular beams using coherent photon processes.

Cold collisions of heavy Σ2 molecules with alkali-metal atoms in a magnetic field: Ab initio analysis and prospects for sympathetic cooling of SrOH(Morita1, Kłos2, Buchachenko3 et al. 2017Phys. Rev. A242441View full textAdd to dashboardCite

“…We find that inelastic spin relaxation in fully spin-polarized Li + SrOH collisions is strongly suppressed (with the ratio of elastic to inelastic collision rates γ > 10 2 -10 3 ), suggesting good prospects for sympathetic cooling of spin-polarized SrOH molecules with Li atoms in a magnetic trap. In the context of rapid experimental progress in buffer-gas cooling and Sisyphus laser cooling of polyatomic radicals [20,35,36], our results open up the possibility of sympathetic cooling of polyatomic molecules with magnetically co-trapped ultracold alkali-metal atoms, potentially leading to new advances in low-temperature chemical dynamics and spectroscopy of large molecules in the gas phase [30,37].…”

“…Cooling and trapping polyatomic molecular radicals is expected to provide new insights into many-mode vibrational dynamics, photochemistry, and chemical reactivity at ultralow temperatures [20,[30][31][32][35][36][37] [20,36].…”

Precision Measurement of Time-Reversal Symmetry Violation with Laser-Cooled Polyatomic Molecules

“…However, the ideas discussed are generally applicable to other polyatomic species. We show that these molecules have the significant additional advantage of being laser coolable, as was recently demonstrated with the polyatomic molecule SrOH [16] and proposed for a number of other species [15,17,18]. The essential property is the nonbonding s electrons being removed from the bonding region by orbital hybridization [19], resulting in highly diagonal Franck-Condon factors (FCFs).…”

“…In particular, for symmetric top molecules the K doublet is analogous to the l doublet, where K is the projection of the total rotational, orbital, and vibrational angular momentum on the symmetry axis [21]. The advantageous features of l doublets are preserved, as is the ability to laser cool species such as YbCH 3 and YbOCH 3 [17,18]. However, K-doublet splittings are even smaller, typically ≲kHz, meaning that complete polarization requires only ≲1 V=cm electric fields, and the excited K levels are even closer to the ground state (typically ∼100 GHz).…”

“…The essential property is the nonbonding s electrons being removed from the bonding region by orbital hybridization [19], resulting in highly diagonal Franck-Condon factors (FCFs). This property is not strongly dependent on the type of functional group bound to the metal atom [17,18]. Thus, polyatomic molecules isoelectronic to suitable diatomic candidates for fundamental physics searches such as BaF, YbF, HgF, and RaF have promise for laser cooling.…”