We use three independent spectroscopic techniques, operating in the millimeter-wavelength range, to study molecule-atom collisions, and validate our quantum-scattering calculations on two recent potential energy surfaces. We study the first pure rotational transition in a CO molecule perturbed by Ar. This molecular system is a good prototype of atmospherically relevant cases. It is, on the one hand, affordable for calculation of the line shape parameters by modern ab initio methods, and on the other hand, is very convenient for experimental studies because of its regular, well spaced rotational spectrum having a moderate intensity. We show that the simulated collision-perturbed spectra, which are based on our fully ab initio calculations, agree with the experimental line profiles at sub-percent level over a wide range (more than four orders of magnitude) of pressures. We demonstrate that the agreement between theory and experiment can be further improved if the model accounts for the collisional transfer of an optical coherence between different rotational transitions (the line-mixing effect). We show that the two surfaces tested in this work lead to a very similar agreement with the experiment. Capability of calculating line shape parameters in a broad range of temperatures is demonstrated.

我们使用三种独立的光谱技术，在毫米波长范围内运行，研究分子-原子碰撞，并验证我们在两个最近的势能表面上的量子散射计算。我们研究了被 Ar 扰动的 CO 分子中的第一个纯旋转跃迁。这个分子系统是大气相关案例的一个很好的原型。一方面，通过现代从头算方法计算线形参数是负担得起的，另一方面，由于其规则的、间隔良好的旋转光谱具有中等强度，因此非常便于实验研究。我们展示了模拟的碰撞扰动光谱，这是基于我们完全从头开始的计算，在很宽的压力范围内（超过四个数量级）与亚百分比水平的实验线轮廓一致。我们证明，如果模型考虑了不同旋转过渡（线混合效应）之间的光学相干性的碰撞转移，则可以进一步提高理论与实验之间的一致性。我们表明，在这项工作中测试的两个表面与实验非常相似。展示了在广泛的温度范围内计算线形参数的能力。