Abstract
Ultracold collisions of the polyatomic species CaOH are considered, in internal states where the collisions should be dominated by long-range dipole–dipole interactions. The computed rate constants suggest that evaporative cooling can be quite efficient for these species, provided they start at temperatures achievable by laser cooling. The rate constants are shown to become more favorable for evaporative cooling as the electric field increases. Moreover, long-range dimer states (CaOH) are predicated to occur, having lifetimes on the order of microseconds.
Highlights
The technology to laser cool molecules leads the way to a wave of truly ultracold molecular species, achieving temperatures on the microKelvin scale rather than the milliKelvin scale [1]
It is not known whether this reaction occurs at low temperatures in the gas phase. This is obviously a detriment to producing and maintaining a stable, ultracold gas of CaOH. For these reasons we will disregard the possibility of the reaction, as the potential energy surface is unknown, and focus instead on ultracold collisions where the molecules are expected to be shielded by the repulsive parts of the dipole-dipole interaction
We here report two significant properties of ultracold collisions of (0, 11, 0) CaOH molecules, at least among those that are dominated by long-range physics
Summary
The technology to laser cool molecules leads the way to a wave of truly ultracold molecular species, achieving temperatures on the microKelvin scale rather than the milliKelvin scale [1] These temperatures are low enough that the molecules can be confined in magnetic [2, 3] or optical dipole traps [4, 5], can be produced in individual quantum states, tend to collide in individual partial waves, and have collisions that respond strongly to laboratory electric and magnetic fields [6]. Central to our approach is that, for certain collisions at ultralow temperature, the scattering rates and their field dependence rely on physics that occurs when the molecules are far apart, that is, on scales larger than the range of the exchange potentials between them This circumstance simplifies the description of scattering, and leads to certain common behaviors. The ones that we single out are: 1) a suppression of inelastic scattering at sufficiently high electric field and sufficiently low temperature, for states that can be optically trapped; and 2) a set of electric-field resonances, previously described as “field linked states,” [14, 15] that could serve as an additional platform for controlling these species and their interaction
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