A sulfur dioxide detection platform based on photoacoustic spectroscopy and a 266.22 nm high-power stabilized...

A ppb-level sulfur dioxide (SO₂) monitoring platform was developed by exploiting standard photoacoustic spectroscopy and a novel, highly stable UV laser. A 266.22 nm LD-pumped solid-state, acousto-optic modulator Q-switched laser with high beam quality (M² =1.0275) and excellent output optical power stability (δ_Pσ ˂ 1 % ∼24 h) was selected as light source of the photoacoustic sensor. The performance of the SO₂ sensor was evaluated in terms of gas flow rate, pressure, and detection sensitivity. An ultimate detection limit of 3 ppb for SO₂ detection in N₂ was demonstrated with 1 s integration time, in laboratory environment. Continuous outdoor monitoring for five days verified the excellent stability and reliability of the reported SO₂ photoacoustic sensor.