A differential absorption spectroscopy system for measuring the concentration of glyoxal in the atmosphere based on LED light source

Abstract

The invention belongs to the technical field of optical measurement and specifically relates to an LED light source-based differential optical absorption spectroscopy system for measuring concentration of glyoxal in the atmosphere. The system of the invention is composed of an LED light, a plane mirror, a main concave mirror, an optical corner reflector, a secondary mirror, a fiber, a spectrometerand a computer, etc. A virtual image generated by the LED light in the plane mirror is positioned near the focus of the main concave mirror; after collimation by the main concave mirror, light beamsenter the atmosphere and reach the optical corner reflector after transmitted for some distance; the light beams are reflected back to the main concave mirror along the original path and are gatheredto the fiber after focusing by the secondary mirror; after light splitting by a spectrometer and photoelectric conversion, absorption spectrum information is obtained; by the least square method for spectral interpretation, the calibrated NO2 standard absorption spectrum is used as a fitting item for inversion of glyoxal to reduce the interference of NO2 with analysis of glyoxal, thereby achievingaccurate measurement of concentration of glyoxal in the atmosphere.

Description

technical field [0001] The invention belongs to the technical field of optical measurement, in particular to a differential absorption spectrum system for measuring the concentration of glyoxal in the atmosphere. Background technique [0002] Glyoxal is the smallest α-dicarbonyl substance present in the atmosphere. It mainly comes from the direct emission of biomass combustion and the oxidation reaction of volatile organic compounds (VOCs) with OH radicals. The oxidation process is also accompanied by the generation of ozone. . The species has an atmospheric lifetime of only a few hours and is subsequently removed by oxidation with OH radicals and heterogeneous reactions on the aerosol surface, so this species is extremely important for the study of atmospheric oxidation and secondary organic aerosol formation . [0003] The measurement of this substance mainly focuses on chromatography, mass spectrometry, and spectroscopic techniques, among which gas phase and liquid chro...

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Problems solved by technology

[0003] The measurement of this substance mainly focuses on chromatography, mass spectrometry, and spectroscopic techniques, among which gas phase and liquid chromatography are relatively cumbersome for the pretreatment process of samples, and cannot be measured quickly and in real time; mass spectrometry requires mechanical vacuum and high voltage power supply, etc. Higher, which greatly increases the cost of scientific research and the difficulty of operation; the spectral techniques used to measure glyoxal are mainly laser-induced fluorescence spectroscopy (LIF), incoherent broadband light source cavity-enhanced absorption spectroscopy (IBBCEAS) and long optical path difference Optical Absorption Spectroscopy (LP-DOAS)

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