Sensitivity enhanced NIR photoacoustic CO detection with SF6 promoting vibrational to translational relaxation process

Photoacoustics

Chongxin Shan¹  Lei Li²  Yang Gao³  Fengtao Han³  Chenguang Liu³  Yingying Qiao³  Liping Tang³ 

[1] School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China;Corresponding author.;School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China;

关键词: Photoacoustic spectroscopy;    Near-infrared light source;    Carbon monoxide sensor;    Vibrational to translational relaxation process;    Sulfur hexafluoride;    High sensitivity;   

DOI  :  

来源: DOAJ

【 摘 要 】

A challenge for slowly relaxing carbon monoxide (CO) molecules detection using photoacoustic spectroscopy (PAS) is to promote the vibration-translation (V-T) relaxation process. Addressing this challenge, a sensitivity enhanced photoacoustic CO sensor with sulfur hexafluoride (SF6) as the promotor is investigated and demonstrated. A 1568 nm near-infrared (NIR) laser diode and a customized optical amplifier are used as the excitation source to generate the photoacoustic signal. A differential photoacoustic cell is simulated and designed to obtain identical laminar flow distribution in the resonant cell to suppress the flow noise. The modulation frequency and added SF6 volume ratio are optimized experimentally to achieve optimal sensitivity. Feasibility and performance of the CO sensor with a small amount of SF6 as promotor is discussed and evaluated, obtaining a ~ 2 times improvement of signal value compared to the one with pure N2 background and resulting in a minimum detection limit of 467.5 ppb for CO detection.

【 授权许可】

Unknown