The room temperature spectrum of the very weak third overtone band of carbon monoxide in natural isotopic abundance is recorded by cavity ring down spectroscopy (CRDS) referenced to a frequency comb, between 8206 and 8465 cm⁻¹. The sensitivity of the recordings (noise equivalent absorption on the order of α_min ∼ 5 × 10⁻¹² cm⁻¹) allowed for measuring lines with intensity as weak as 1 × 10⁻³⁰ cm/molecule at a recording pressure limited to 10.0 Torr. The use of low pressure values (1.0 and 10.0 Torr) helped to minimize the impact of profile effects on the derived line positions and line intensities. The line profile analysis was performed using the speed dependent Nelkin-Ghatak model for the 10 Torr recordings while the Voigt profile was found sufficient to account for the line shapes recorded at 1.0 Torr.

Overall, line parameters of 227 transitions are derived. The observed transitions belong to the 4-0 band of the ¹²C¹⁶O, ¹³C¹⁶O, ¹²C¹⁸O and ¹²C¹⁷O isotopologues present in natural abundance in the sample and to the 5-1 hot band of ¹²C¹⁶O. For a large part of the observations, line positions are reported with accuracy as good as 4 × 10⁻⁶ cm⁻¹ (∼120 kHz). The self-induced line shift of the 4-0 band is reported for the first time from the position values at 1 and 10 Torr. Using literature values of the 1-0, 2-0 and 3-0 bands, the vibrational dependence of the self-induced pressure shift in CO is discussed. The experimental values of the ¹²C¹⁶O v = 4 energy levels J < 26 are reproduced with a standard deviation of 2.5 × 10⁻⁶ cm⁻¹ (75 kHz). The intensities of the ¹²C¹⁶O lines reported with an accuracy better than 1% show an overall good agreement with literature values in particular with those included in the HITRAN database.

天然同位素丰度中一氧化碳非常弱的第三泛音带的室温光谱通过腔环衰荡光谱法（CRDS）记录，参考频率梳为8206和8465 cm ^-1之间。录音的灵敏度（量级噪声等效吸收α_分钟 〜  5×10 ^{- 12} 厘米^-1允许测量线用强度为弱为1×10）^{- 30} 记录压力不超过10.0托的情况下，每平方厘米/分子。低压值（1.0和10.0 Torr）的使用有助于最小化轮廓效应对导出的管线位置和管线强度的影响。使用速度相关的Nelkin-Ghatak模型对10 Torr记录进行线轮廓分析，而Voigt轮廓足以说明以1.0 Torr记录的线形。

总的来说，导出了227个过渡的线参数。所观察到的转变属于4-0频带的¹² Ç ¹⁶ O，¹³ Ç ¹⁶ O，¹² Ç ¹⁸ O和¹² Ç ¹⁷ ö同位素存在于天然丰度的样品中和到的5-1热轧带¹² Ç ¹⁶ O.对于观测的很大一部分，线位置被报告的精度一样好4×10 ^{- 6} 厘米^-1（〜120 kHz）。首次从1和10 Torr的位置值报告了4-0波段的自感应线移。使用1-0、2-0和3-0波段的文献值，讨论了CO中自感应压力位移的振动相关性。所述的实验值¹² Ç ¹⁶ ö v  = 4个能级Ĵ  <26再现具有2.5×10的标准偏差^{- 6} 厘米^-1（75千赫）。报告的¹² C ¹⁶ O谱线的强度优于1％，显示出与文献值的总体良好一致性，尤其是与HITRAN数据库中包含的那些值。