Acta Optica Sinica, Vol. 34, Issue 1, 130002 (2014)
Mid-IR Ultra-Sensitive CO Detection Based on Pulsed Quartz Enhanced Photoacoustic Spectroscopy
Lei Dong*, Weiguang Ma, Lei Zhang, Wangbao Yin, and Suotang Jia
- [in Chinese]
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.
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