We carry out quantum inelastic scattering calculations of collisions of Rb atoms with inverting NH3 and ND3 molecules in the energy range between 0 and 100 cm-1, which are important for experiments using velocity-controlled molecular beams to probe scattering resonances. We focus on molecules initially in the upper level of the ammonia inversion doublet, which are low-field-seeking and can be controlled in a Stark decelerator. We calculate the integral elastic and state-to-state inelastic cross sections in the coupled states approximation. We demonstrate the presence of both shape and Feshbach resonances in the elastic and inelastic cross sections at low collision energies and discuss their origin in terms of the bound states of Rb--ND3 complex. We also consider elastic and inelastic cross sections in the ultracold regime, using close-coupling calculations, in order to assess the viability of sympathetic cooling of ND3 by Rb. The inelastic cross section for relaxation to the lower level of the inversion doublet is smaller than expected for such a strongly coupled system, but is still likely to be too large to allow sympathetic cooling for ND3 in low-field-seeking states. However, there is a good prospect that sympathetic cooling will be possible for molecules in high-field-seeking states, even when the collision partner is a magnetically trapped atom in a low-field-seeking state.
Resonant dipolar collisions of ultracold molecules induced by microwave dressing
我们演示了微波敷料上的超冷，费米子${}^{23}$ Na ${}^{40}$ K基态分子和观察共振偶极碰撞的横截面超过三倍的$s$波幺正极限。这些碰撞的起源是接近分子的偶极子沿着分子间轴的共振排列，这导致了强烈的吸引力。我们解释我们的观察与一个概念上简单的两个国家的图片的基础上的康登近似。此外，我们进行耦合通道的计算，同意与实验观察到的碰撞率。虽然这里观察到的碰撞作为激光诱导的损失，微波敷料上的化学稳定的分子被困在盒电位可以使分子的强烈相互作用的偶极气体的创建。
Controlled state-to-state atom-exchange reaction in an ultracold atom-dimer mixture
超冷分子提供了在接近零度的温度下研究化学反应的绝佳机会。虽然在探索超冷双分子反应方面已经取得了显著的进展，但研究通常限于反应物的总损失率的测量。反应产物的检测将为理解反应机理提供新的思路，并为研究态-态反应动力学提供了独特的机会。在这里，我们报告的放能原子交换反应中的超冷原子二聚体混合物的直接观察。观察到了原子和分子产物，并表征了量子态。通过改变磁场，可以开启或关闭反应，并且可以控制反应速率。该反应是有效的，我们已经测量了状态到状态的反应速率高达$1.1(3)\times10^{-9}$ cm $^{3}/$ s从反应物和产物的时间演变。我们的工作代表了一个可控的量子态选择/分辨超冷反应的实现。所观察到的原子交换反应也是Feshbach分子与费米子原子之间有效的自旋交换相互作用，可以用来实现超冷原子和分子的近藤效应的量子模拟。
