Department of Chemistry, Stanford University, Stanford, CA, USA.
Nat Chem. 2022 Jun;14(6):658-663. doi: 10.1038/s41557-022-00926-z. Epub 2022 May 2.
The collision dynamics between a pair of aligned molecules in the presence of a partial-wave resonance provide the most sensitive probe of the long-range anisotropic forces important to chemical reactions. Here we control the collision temperature and geometry to probe the dynamics of cold (1-3 K) rotationally inelastic scattering of a pair of optically state-prepared D molecules. The collision temperature is manipulated by combining the gating action of laser state preparation and detection with the velocity dispersion of the molecular beam. When the bond axes of both molecules are aligned parallel to the collision velocity, the scattering rate drops by a factor of 3.5 as collision energies >2.1 K are removed, suggesting a geometry-dependent resonance. Partial-wave analysis of the measured angular distribution supports a shape resonance within the centrifugal barrier of the l = 2 incoming orbital. Our experiment illustrates the strong anisotropy of the quadrupole-quadrupole interaction that controls the dynamics of resonant scattering.
在存在分波共振的情况下，一对对准分子的碰撞动力学为化学反应中重要的长程各向异性力提供了最敏感的探针。在这里，我们控制碰撞温度和几何形状来探测一对经光态制备的 D 分子的冷（1-3 K）旋转非弹性散射的动力学。通过将激光态制备和检测的选通作用与分子束的速度分散结合起来，可以操纵碰撞温度。当两个分子的键轴都平行于碰撞速度对齐时，当碰撞能量>2.1 K 被移除时，散射率下降了 3.5 倍，这表明存在一个与几何形状有关的共振。对测量的角分布的分波分析支持在 l=2 入射轨道的离心势垒内存在一个形状共振。我们的实验说明了控制共振散射动力学的四极-四极相互作用的强烈各向异性。
