We present an experimental study of carbon dioxide absorption in the transparency window near 700 nm, where different calculations predicted several extremely weak bands. The measurements were done using the optical frequency comb-assisted cavity ring-down spectrometer reaching sensitivity (noise-equivalent absorption) of cm. None of 21 lines, predicted by the most comprehensive calculations, were detected in five separate spectral regions near 700 nm. Our estimated detection limit ranges between 3 and 21 times lower than the expected peak absorption in the conditions of the experiment.

中文翻译：

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理论上预测的 700 nm 附近的 CO2 谱线未观测到

我们提出了一项关于 700 nm 附近透明窗口中二氧化碳吸收的实验研究，其中不同的计算预测了几个极弱的谱带。使用光频梳辅助腔衰荡光谱仪进行测量，灵敏度（噪声等效吸收）达到 cm。通过最全面的计算预测，在 700 nm 附近的 5 个独立光谱区域中没有检测到 21 条谱线。我们估计的检测限比实验条件下预期的峰值吸收低 3 到 21 倍。