Development of a 443 nm diode laser-based differential photoacoustic spectrometer for simultaneous measurements of aerosol absorption and NO2

The experimental data are obtained by the differential photoacoustic spectrometer established in this paper. A novel photoacoustic resonator was designed and employed in the D-PAS for controlling a large flow rate, improving response time, and keeping the flow noise at a low level. The measured results of NO2 are consistent with the NOx analyzer and environmental monitoring station results.