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How to detect NO2 more sentitive? TEXT SIZE: A A A
Date:2017.01.23 Author:Kun Liu Clicks:

Nitrogen dioxide (NO2) is a major primary pollutant in the atmosphere. It also plays a key role in the tropospheric chemistry reactions that produce ground level ozone (O3). Conventional sensors for measurements of ambient NO2 concentration have certain drawbacks such as that they are slow (minutes-hours) and non selective in discriminating between NO and NO2, particularly at low concentrations. How to improve it ?

Recently, through cooperation with Prof. Frank Tittel at Rice University, Dr. Kun Liu from Prof. XIAOMING Gao’s group at Anhui Institute of Optics and Fine Mechanics (AIOFM), Hefei Institutes of Physical Science, Chinese Academy of Sciences, has completed the development and performance evaluation of a NO2 sensor based on faraday rotation spectroscopy (FRS). FRS exploits magnetic circular birefringence (MCB) observed in the vicinity of Zeeman split absorption lines. The advantages of FRS include high detection sensitivity, zero background and free from the influence of diamagnetic species, such as humidity and carbon dioxide. The sensitivity of the Dr. Liu developed FRS based NO2 sensor was enhanced by combining a compact multi-pass absorption cell which widely used in tunable laser absorption spectroscopy, and an ultra-high sensitivity of 95 pptv for NO2 detection was achieved. The developed FRS based NO2 sensor was successfully applied for long time, field measurements of atmospheric NO2. The sensor was also capable of remote access which enabled real-time monitoring of the sensor performance from anywhere via internet. This function was successfully demonstrated by controlling the NO2 sensor located in Houston, TX from Hefei, China, ~10,000 miles from its location in the USA.

These results entitled "Development of a mid-infrared nitrogen dioxide sensor based on Faraday rotation spectroscopy" have been published in Sensors and Actuators B: Chemical.

The work was supported by the National Natural Science Foundation of China and a US National Science Foundation (NSF) ERC MIRTHE award.




                                         Schematic of the FRS based NO2 sensor (Image by Kun liu)



                     Episode of high concentration of NO2 observed during measurements (Image by Kunliu 



              Diurnal profiles of NO2 (a), (b) mean values of NO2 concentration levels during a field measurement campaign, and (c) O3 concentrations obtained during the measurement campaign (Image by Kun liu).  

The article Link:


Development of a mid-infrared nitrogen dioxide sensor based on Faraday rotation spectroscopy



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