Accurate spectroscopic data of carbon dioxide are widely used in many important applications, such as carbon monitoring missions. Here, we present comb-locked cavity ring-down saturation spectroscopy of the second most abundant isotopologue of CO₂, ¹³C¹⁶O₂. We determined the positions of 88 lines in three vibrational bands in the 1.6 μm region, 30011e/30012e/30013e–00001e, with an accuracy of a few kHz. Based on the analysis of combination differences, we obtained for the first time the ground-state rotational energies with kHz accuracy. We also provide a set of hybrid line positions for 150 ¹³C¹⁶O₂ transitions. The rotational energies (J < 50) in the 30013e vibrational state can be fitted by a set of rotational and centrifugal constants with deviations within a few kHz, indicating that the 30013e state is free of perturbations. These precise isotopic line positions will be utilized to improve the Hamiltonian model and quantitative remote sensing of carbon dioxide. Moreover, they will help to track changes in the carbon source and sink through isotopic analysis.

中文翻译：

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以千赫兹精度测定 13C16O2 的旋转振动能

准确的二氧化碳光谱数据广泛应用于许多重要应用，例如碳监测任务。在这里，我们提出了 CO ₂的第二丰富同位素体¹³ C ¹⁶ O ₂的梳状锁定腔衰荡饱和光谱。我们确定了 1.6 μm 区域 30011e/30012e/30013e–00001e 三个振动带中 88 条线的位置，精度为几 kHz。基于组合差异分析，我们首次获得了kHz精度的基态旋转能量。我们还提供了一组用于 150 ¹³ C ¹⁶ O ₂跃迁的混合线位置。 30013e振动态下的旋转能（J < 50）可以通过一组偏差在几kHz以内的旋转和离心常数来拟合，表明30013e态没有扰动。这些精确的同位素线位置将用于改进哈密顿模型和二氧化碳定量遥感。此外，它们将有助于通过同位素分析跟踪碳源和碳汇的变化。