基于双共振吸收光谱法的14CO2探测

快速且准确地定量探测¹⁴CO₂在许多领域都有着重要应用. 超灵敏的光腔衰荡光谱技术是一种极具潜力的光学探测方法，但其存在灵敏度不足和易受其他CO₂同位素/杂质分子干扰的问题. 本文提出利用阶梯型双共振光谱法将¹⁴CO₂从基态激发至中间能级后，再用光腔衰荡光谱法去探测. 双共振的吸收过程可以有效提高探测的选择性. 本文分析了双共振吸收光谱的定量探测能力，模拟结果显示双共振光谱探测是无多普勒的，可以减少其他分子的吸收干扰，有望实现亚ppt水平的¹⁴CO₂高选择性探测.

Detection of Radiocarbon Dioxide with Double-Resonance Absorption Spectroscopy

Fast and accurate quantitative detection of sup>14CO₂ has impor-tant applications in many fields. The optical detection method based on the sensitive cavity ring-down spectroscopy technol-ogy has great potential. But currently it has diffculties of insufficient sensitivity and susceptibility to absorption of other isotopes/impurity molecules. We propose a stepped double-resonance spectroscopy method to excite sup>14CO₂ molecules to an intermediate vibrationally excited state, and use cavity ring-down spectroscopy to probe them. The two-photon process significantly improves the selectivity of detection. We derive the quantitative measurement capability of double-resonance absorption spectroscopy. The simulation results show that the double-resonance spectroscopy measurement is Doppler-free, thereby reducing the effect of other molecular absorption. It is expected that this method can achieve high-selectivity detection of sup>14CO₂ at the sub-ppt level.