Recent experiments on rotational quenching of HD in the v = 1, j = 2 rovibrational state in collisions with H₂, D₂, and He near 1 K have revealed strong stereodynamic preference stemming from isolated shape resonances. So far, the experiments and subsequent theoretical analyses have considered the initial HD rotational state in an orientation specified by the projection quantum number m or a coherent superposition of different m states. However, it is known that such stereodynamic control is generally not effective in the ultracold energy regime due to the dominance of the incoming s-wave (l = 0, partial wave). Here, we provide a detailed analysis of the stereodynamics of rotational quenching of HD by He with both m and m′ resolution, where m′ refers to the inelastically scattered HD. We show the existence of a significant m dependence in the m′-resolved differential and integral cross sections even in the ultracold s-wave regime with a factor greater than 60 for j = 2 → j′ = 1 and a factor greater than 1300 for j = 3 → j′ = 2 transitions. In the helicity frame, however, the integral cross section has no initial orientation (k) dependence in the ultracold energy regime, even resolving with respect to the final orientation (k′). The distribution of final rotational state orientations (k′) is found to be statistical (uniform), regardless of the initial orientation.

中文翻译：

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超冷旋转非弹性碰撞的立体动力学

HD在v = 1，j = 2振动状态下与H ₂，D ₂和He接近1 K碰撞时对HD进行旋转淬火的最新实验表明，强烈的立体动力学偏好是由孤立的形状共振引起的。到目前为止，实验和随后的理论分析已经考虑了由投影量子数m或不同m状态的相干叠加指定的取向的初始HD旋转状态。但是，众所周知，由于进入的s波占主导地位，这种立体动力学控制通常在超冷能量状态下无效（l= 0，部分波）。在这里，我们提供了由He在m和m '分辨率下对HD旋转淬灭的立体动力学的详细分析，其中m '指的是非弹性散射的HD。我们显示了即使在超冷s波态中，在m ′分辨的微分和积分截面中也存在显着的m依赖性，其中j = 2→ j ′= 1的因子大于60，对于j = 2的因子大于1300。j = 3→ j '= 2个转换。但是，在螺旋框架中，整体横截面没有初始方向（k）依赖于超冷能态，甚至相对于最终取向（k '）也可以解析。发现最终旋转状态取向（k '）的分布是统计的（均匀的），而与初始取向无关。