On-line measuring system and on-line measuring method for concentration of NO3 free radicals in atmosphere

Abstract

The invention discloses an on-line measuring system and method for the concentration of NO3 free radicals in the atmosphere based on broadband cavity-enhanced absorption spectroscopy. The on-line measuring system at least comprises a light source controller, a light source, a first convex lens, a second convex lens, a pair of high-reflectivity lenses, a detection cavity, an optical fiber, a spectrometer and a zero-point generator. According to the invention, the pair of high-reflectivity lenses compose a resonant cavity, a LED is used as the light source, and the spectrometer is used as a detector; dynamic zero points are employed for elimination of the influence of other absorbed components on the measurement of NO3 free radicals, so on-line accurate measurement of the NO3 free radicals in the atmosphere is realized. The on-line measuring system and method provided by the invention have the characteristics of low detection limit, high sensitivity, high temporal-spatial resolution, high stability and low cost.

Description

technical field [0001] The invention belongs to the technical field of air quality measurement and relates to NOx in the atmosphere 3 On-line measurement of free radicals, especially related to a kind of atmospheric NO based on broadband cavity-enhanced absorption spectroscopy 3 Free radical concentration online measurement system and method. Background technique [0002] Atmospheric NO 3 Free radicals are very important oxidants in the nighttime atmosphere. Their high activity, short atmospheric lifetime and low concentration levels make their accurate online measurement very difficult. Existing atmospheric NO 3 Free radical online measurement techniques include differential absorption spectroscopy (DOAS), laser-induced fluorescence (LIF) and cavity ring-down spectroscopy (CRDs). The average concentration cannot obtain the concentration information on a small spatial scale, and it is easily affected by the environment; the complex calibration of LIF technology can achie...

AI Technical Summary

Problems solved by technology

[0002] Atmospheric NO 3 Free radicals are very important oxidants in the nighttime atmosphere. Their high activity, short atmospheric lifetime and low concentration levels make their online accurate measurement very difficult.

Existing atmospheric NO 3 Free radical online measurement techniques include differential absorption spectroscopy (DOAS), laser-induced fluorescence (LIF) and cavity ring-down spectroscopy (CRDs). The average concentration cannot obtain the concentration information on a small spatial scale, and it is easily affected by the environment; the complex calibration of LIF technology can achieve accurate measurement, its sensitivity is low, the operation is complicated and the maintenance cost is high; the CRDs technology measures the light intensity in the resonant cavity The change of the ring-down time is used to obtain the concentration level of the substance to be measured. This technology uses a narrow-band laser as the light source and has high requirements for system stability.

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