Recently, Prof. GAO Xiaoming's group from the Anhui Institute of Optics and Fine Mechanics (AIOFM) of the Hefei Institutes of Physical Science (HFIPS) demonstrated how they designed and manufactured a photoacoustic spectroscopy based sensor to measure aerosols and nitrogen dioxide (NO₂) simultaneously.

Atmospheric aerosols and NO₂ are considered as main pollutants in the air, while the online measurement of aerosol absorption characteristics still faces many challenges. Since the photoacoustic spectroscopy (PAS) is not affected by light scattering, and the acoustic transducer is not limited by the wavelength of light, it has unique advantages in the measurement of aerosols and trace gases.

"This PAS (D-PAS) is based on a 443 nm laser diode," explained Prof. LIU Kun, member of the research team. "By optimizing the structure of acoustic resonator, we realized high-sensitivity and large-flow rate for online measurement of aerosol absorption and NO₂."

During the experiment, both the intercomparison and good consistency between the developed D-PAS and commercial NO_X analyzer when measuring NO₂ in the atmosphere proved the reliability of this novel D-PAS sensor.

With important potential application in the development of aerosol absorption and NO₂ analyzer, this sensor can be applied to the field of atmospheric measurement or environmental monitoring.

The research work was supported by the National Natural Science Foundation of China and the National Key Research and Development Program.

Experimental setup of the D-PAS (Image by LIU Kun) 

Calibration results of the developed D-PAS (Image by LIU Kun) 

Time series measurements of aerosol absorption coefficient and NO₂ concentration (Image by LIU Kun)