We use numerically exact quantum dynamics calculations to demonstrate universal stereoselectivity of cold collisions of ${}^2\mathrm{\Pi }$ molecules with ${}^1\mathrm{S}$-state atoms in an external electric field. We show that cold collisions of OH molecules in their low-field-seeking $f$-states, whose dipole moments are oriented against the field direction, are much more likely to lead to inelastic scattering than those of molecules oriented along the field direction, causing nearly perfect steric asymmetry in the inelastic collision cross sections. The universal nature of this effect is due to the threshold suppression of inelastic scattering between the degenerate $\pm M$ Stark sublevels of the high-field-seeking $e$-state, where $M$ is the projection of the total angular momentum of the molecule on the field axis. Above the $\mathrm{\Lambda }$-doublet threshold, the stereodynamics of inelastic atom-molecule collisions can be tuned via electric-field-induced resonances, which enable effective control of Ne $+$ OH scattering over the range of collision energies achievable in current merged beam experiments.

中文翻译：

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电场中冷原子-分子碰撞的通用立体动力学

我们使用数值精确的量子动力学计算来证明冷碰撞的普遍立体选择性 ${}^2\mathrm{\Pi }$ 分子与 ${}^1\mathrm{秒}$- 外电场中的状态原子。我们表明 OH 分子在其低场寻求中的冷碰撞$F$偶极矩与场方向相反的状态比沿场方向取向的分子更容易导致非弹性散射，从而在非弹性碰撞截面中导致近乎完美的空间不对称。这种效应的普遍性质是由于退化之间的非弹性散射的阈值抑制$\pm 米$ 高场寻求的鲜明子层次 $\mathrm{电子}$-状态，其中 $米$是分子总角动量在场轴上的投影。以上$\mathrm{\Lambda }$-doublet 阈值，非弹性原子-分子碰撞的立体动力学可以通过电场引起的共振进行调整，从而能够有效控制 Ne $+$ 在当前合并光束实验中可实现的碰撞能量范围内的 OH 散射。