Knowledge of rotational energy transfer (RET) involving carbon monoxide (CO) molecules is crucial for the interpretation of astrophysical data. As of now, our nearly perfect understanding of atom-molecule scattering shows that RET usually occurs by only a simple “bump” between partners. To advance molecular dynamics to the next step in complexity, we studied molecule-molecule scattering in great detail for collision between two CO molecules. Using advanced imaging methods and quasi-classical and fully quantum theory, we found that a synchronous movement can occur during CO-CO collisions, whereby a bump is followed by a move similar to a “do-si-do” in square dancing. This resulted in little angular deflection but high RET to both partners, a very unusual combination. The associated conditions suggest that this process can occur in other molecule-molecule systems.

涉及一氧化碳（CO）分子的旋转能量转移（RET）知识对于解释天体物理数据至关重要。到目前为止，我们对原子-分子散射的近乎完美的理解表明，RET通常仅通过伙伴之间的简单“碰撞”发生。为了使复杂的分子动力学进一步发展，我们对两个CO分子之间的碰撞进行了详细的分子-分子散射研究。使用先进的成像方法以及准经典和完全量子理论，我们发现在CO-CO碰撞期间可能发生同步运动，从而在颠簸之后跟随着类似于广场舞中“ do-si-do”的运动。这导致几乎没有角度偏移，但对两个伙伴的RET都很高，这是非常不同的组合。