Sub‐ppb nitrogen dioxide detection based on resonant photoacoustic spectroscopy

Abstract A photoacoustic spectroscopy sensor for nitrogen dioxide (NO 2 ) detection was presented based on a high‐power broadband blue diode laser emitting at 446 nm. An optical chopper was replaced by a transistor transistor logic modulation signal generated by the signal generator to reduce mechanical noise. The detection limit of NO 2 sensor system reached to 46 ppt by the Allan variance analysis on the benefit of reflection‐enhanced. A continuous detection of NO 2 in the atmosphere for 48 h was implemented in collaboration with an adaptive Kalman filter for lessening the noise in the measurement. The experimental results were highly consistent with the data of the China National Environmental Monitoring Center, demonstrating the accuracy and reliability of our NO 2 sensor system. This work provides a promising method for NO 2 and other atmospheric pollution gasses.