The Science Island team has made new progress in the Faraday rotation spectrum NOx two-component synchronous detection

Recently, the team of Gao Xiaoming, a researcher at the Institute of Optics and Light of the Hefei Institute of Physical Sciences, the Chinese Academy of Sciences, has made new progress in the simultaneous detection of NOx two-component in the static magnetic field Faraday rotation spectrum. The relevant research results were published in the international TOP journal under the title of "Dual mid-infrared wavelength Faraday rotation Spectrum NOx Sensor based on Ndfeb ring Magnetic Array". Sensors and Actuators: B. Chemically.

Nitrogen oxides (NOx = NO+NO2) are at the center of atmospheric chemical reactions, affecting the concentration of ozone, hydroxyl and peroxygen free radicals, and are important precursors to the formation of photochemical smog, acid rain and ash haze pollution. At the same time, NOx released by farmland, wetlands and other ecosystems plays an important role in the global nitrogen cycle.

Aiming at the problems such as slow measurement rate and lack of selectivity for NO and NO2 in the detection of NOx by traditional chemiluminescence method, Dr. Liu Kun, associate researcher Cao Yuante and others proposed a static magnetic field Faraday rotation spectrum NOx two-component synchronous detection device based on Ndfeb ring magnetic array. By designing a gas absorption cell with single cavity and double optical path and coaxial coupling it with Ndfeb ring magnetic array, the interaction between two linearly polarized beams of different bands and NOx molecules under static magnetic field is promoted. At the same time, in view of the problem that the left and right sides of the Ndfeb ring magnetic array are opposite to the internal axial magnetic field, resulting in partial cancellation of the magneto-optical signal stimulated by the internal axial magnetic field, it is proposed that the length of the absorption pool should be less than or equal to the length of the permanent magnet array. The modulation of the detected laser polarization state is generated by combining the wavelength modulation spectrum with the static magnetic field, and the detection sensitivity of 0.58 ppb NO2 and 0.95 ppb NO is achieved at 23.7 m optical path and 100s integration time. This work lays a foundation for the research team to further study soil-plant-atmosphere NOx interface fluxes in ecosystems based on the vorticity correlation method.

This work was supported by the Research Equipment Development Project of the Chinese Academy of Sciences, the National Natural Science Foundation of China, the Advanced Laser Technology Laboratory Open Fund of Anhui Province, the President's Fund of the Hefei Institute of Physical Sciences, and the China Postdoctoral Surface Fund.

Spatial magnetic field intensity distribution between single cavity double optical path gas pool and Ndfeb ring magnetic array

Faraday rotation spectrum NOx two-component synchronous detection device

The relationship between signal, noise and signal-to-noise ratio of Faraday rotation spectrum and deflection Angle of analyzer

Source: Anhui Institute of Optics and Fine Mechanics