发展了一种超高灵敏的CO痕量气体测量装置，该装置采用4.65 μm脉冲式中红外外腔量子级联激光器作为激发光源，结合石英增强光声光谱技术，对2135~2225 cm-1之间的CO基频振动光谱带R支进行连续光谱扫描。水被加入到被测气体中，以加快较慢的CO分子振动平动弛豫率。在锁相放大器时间常数为3 ms，激光器占空比和扫描速率为50 %和18 cm-1/s时，获得的最小探测极限为4.6×10-8 (体积分数)，与之对应的归一化噪声等效吸收系数为1.07×10-8 cm-1W/Hz。

An ultra-sensitive gas sensor for trace carbon monoxide (CO) detection is developed. The fundamental ro-vibrational absorption bands of CO from 2135 cm-1 to 2225 cm-1 is continuously measured using a 4.65 μm pulsed external-cavity quantum cascade laser and quartz enhanced photoacoustic spectroscopy. The water vapor, acting as a catalyst for vibrational energy transfer, is added to the targeted analyte mixture to improve signal amplitude. A detection limit of 4.6×10-8 is obtained for 3-ms lock-in amplifier time constant at atmospheric pressure with a laser scan rate of 18 cm-1/s and a 50% duty cycle, which corresponds to a normalized equivalent absorption coefficient of 1.07×10-8 cm-1W/Hz.