Infrared cavity ring-down spectroscopy trace gas detection method based on quantum cascade laser

Abstract

The invention discloses an infrared cavity ring-down spectroscopy trace gas detection method based on quantum cascade laser; comprising the following steps: using a tunable quantum cascade laser as alight source, and selecting measuring waveband and wavelength scan step length aiming at spectrum line characteristic of the gas to be detected; respectively measuring the cavity ring-down time of each wavelength in the cavity with absorption or without absorption by cavity ring-down technique, and calculating the gas absorption coefficient of corresponding wavelength so as to obtain a relation curve that is an absorption spectrogram of the measured gas absorption coefficient and toned laser wavelength. The spectrogram is contrasted with spectrum line characteristic of corresponding gas in HITRAN database, thereby being capable of analyzing and determining weather the measured gas contains the predetermined gas component; the absolute concentration of the gas to be measured can be calculated and obtained and the absolute concentration of the gas to be measured can be measured through scaling measurement by using absorption peak wavelength of the absorption spectrum as the best detection wavelength and the relation among the gas absorption coefficient of the wavelength, the absorption cross section and concentration. The method has high measuring sensitivity and high property of resisting interference so that the fast and exact on-line analysis and detection of multiple trace gases are easily realized.

Description

technical field [0001] The invention relates to a detection method of trace gas, in particular to an infrared optical cavity ring-down spectrum trace gas detection method based on quantum cascade laser. Background technique [0002] Trace gas analysis and detection technology has a wide range of application requirements in many fields such as toxic gas and explosive gas detection, atmospheric monitoring, industrial waste gas and vehicle exhaust pollution measurement, agricultural environmental gas monitoring, disease diagnosis, and various industrial manufacturing process monitoring. Gas detection methods are mainly divided into two categories: traditional chemical detection methods and new spectral detection methods. Infrared cavity ring-down spectroscopy technology is an infrared absorption spectroscopy technology based on cavity ring-down technology (CRDS). Optical cavity ring-down technology measures the ring-down time of light in the ring-down cavity, which is only rela...

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Problems solved by technology

The pulsed OPO light source used in the mid-to-far infrared band is bulky, expensive, and difficult to maintain, which is not conducive to instrumentation

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