该研究团队进行了一氧化氮(NO)和氘化氨(ND3)分子在0.1/cm到580/cm能量范围内的非弹性碰撞截面测量，具有完整的量子态分辨率。在相互作用势井深度约为100/cm以下的能量范围内，他们观察到来自奇特U形轨迹的向后光辉。在0.2/cm以下的能量范围内，他们观察到Langevin俘获模型的崩溃，并将其解释为在碰撞期间相互极化被抑制，从而有效地关闭了分子偶极矩。基于NO-ND3势能面的第一性原理散射计算，揭示了具有相反宇称的近简并旋转能级在低能偶极碰撞中的关键作用。
研究人员表示，冷极性分子之间的碰撞代表了一个迷人的研究前沿，但已被证明很难在实验上探测。
附：英文原文
Title: Quantum state–resolved molecular dipolar collisions over four decades of energy
Author: Guoqiang Tang, Matthieu Besemer, Stach Kuijpers, Gerrit C. Groenenboom, Ad van der Avoird, Tijs Karman, Sebastiaan Y. T. van de Meerakker
Issue&Volume: 2023-03-10
Abstract: Collisions between cold polar molecules represent a fascinating research frontier but have proven hard to probe experimentally. We report measurements of inelastic cross sections for collisions between nitric oxide (NO) and deuterated ammonia (ND3) molecules at energies between 0.1 and 580 centimeter-1, with full quantum state resolution. At energies below the ~100-centimeter-1 well depth of the interaction potential, we observed backward glories originating from peculiar U-turn trajectories. At energies below 0.2 centimeter-1, we observed a breakdown of the Langevin capture model, which we interpreted in terms of a suppressed mutual polarization during the collision, effectively switching off the molecular dipole moments. Scattering calculations based on an ab initio NO-ND3 potential energy surface revealed the crucial role of near-degenerate rotational levels with opposite parity in low-energy dipolar collisions.
DOI: adf9836
Source: https://www.science.org/doi/10.1126/science.adf9836