Precise Detection Technology for Sensing Nitrogen Dioxide in the Air

Unique detection technology that can realize fast and sensitive detection of nitrogen dioxide (NO2) was established by a research group led by Professor Zhang Weijun of the Hefei Institute of Physical Sciences (HFIPS), Chinese Academy of Sciences (CAS) recently.

Schematic diagram of the experimental installation of the device AM-CEAS. (Image authorship: Zhou Jiacheng).

Relevant research results are published in the journal Analytical Chemistry.

NO2 is one of the most significant pollutants in the troposphere and plays a very important role in the process of air pollution. Therefore, NO measurements are very sensitive and accurate2 are of great importance for research in atmospheric chemistry and the prevention and control of air pollution.

In this study, researchers were the first to apply the amplitude modulation method to multimode diode lasers and created an amplitude modulated multimode diode laser spectroscopy (AM-CEAS) system for high-sensitivity NO.2 detection.

The new instrument, which is controlled by TTL at 35 kHz, operated at 406 nm, using phase-sensitive detection for supersensitive absorption measurement. The accuracy of the instrument was 35 pptv and 8 pptv, respectively, during the data collection time of 1 second and 30 seconds, which is more than 4 times lower than that achieved by resonance spectroscopy (CRDS) using the same instrument. .

Integration with call reduction time measurement, AM-CEAS technology can remove the mirror reflectivity calibration process, thus not reaching2 absolute concentration measurements. It also has the advantages of high injection efficiency, such as CRDS axis alignment, low resonance noise level, such as off-axis alignment CEAS, and phase-sensitive modulation spectroscopy detection.

The AM-CEAS instrument is a basic, reliable, cost-effective tool for self-calibration, ideal for long-term stability and low maintenance requirements, which has favorable prospects in research and operational applications.

The newly developed instrument undergoes extensive field observation in the city of Beijing and is used to calculate total reactive nitrogen in the air during the 2022 Beijing Winter Olympics.

This study was supported by the National Science Foundation of China, the Second Scientific Expedition and Research Program of the Tibetan Plateau, the CAS Youth Innovation Promotion Association, the Chinese Academy of Sciences Tool Development Project and the HFIPS Foundation Director.

Information about the magazine:

Zhou, J., et al. (2022) Amplitude-Modulated Absorption Spectroscopy with Improved Absorption with Phase-Sensitive Detection: A New Approach to Rapid and Sensitive NO Detection2. Analytical Chemistry.


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