Chemical Sciences Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Laboratoire de Météorologie Dynamique/IPSL, CNRS, Sorbonne Université, Ecole Polytechnique, Institut polytechnique de Paris, Ecole Normale Supérieure, PSL Research University, 4 place Jussieu, 75252, Paris, France.
Phys Rev Lett. 2023 Apr 7;130(14):143001. doi: 10.1103/PhysRevLett.130.143001.
Using cavity ring-down spectroscopy to probe R-branch transitions of CO in N_{2}, we show that the spectral core of the line shapes associated with the first few rotational quantum numbers, J, can be accurately modeled using a sophisticated line profile, provided that a pressure-dependent line area is introduced. This correction vanishes as J increases and is always negligible in CO-He mixtures. The results are supported by molecular dynamics simulations attributing the effect to non-Markovian behavior of collisions at short times. This work has large implications because corrections must be considered for accurate determinations of integrated line intensities, and for spectroscopic databases and radiative transfer codes used for climate predictions and remote sensing.
利用腔衰荡光谱探测 N_{2}中 CO 的 R 支跃迁，我们表明，与前几个转动量子数 J 相关的谱线形状的光谱核心可以通过使用复杂的谱线轮廓进行精确建模，前提是引入与压力有关的线面积。随着 J 的增加，该修正项趋于零，并且在 CO-He 混合物中总是可以忽略不计。分子动力学模拟支持这一结果，该模拟将这种效应归因于短时间内碰撞的非马尔可夫行为。这项工作具有重要意义，因为必须考虑修正项才能准确确定积分线强度，以及用于气候预测和遥感的光谱数据库和辐射转移代码。
