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

ABSTRACT: 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.

SUBMITTER: Qiao Y 

PROVIDER: S-EPMC8844726 | biostudies-literature | 2022 Mar

REPOSITORIES: biostudies-literature