Trace gas detection device and method based on intermediate infrared quantum cascade laser direct absorption spectrum method

Abstract

The invention discloses a trace gas detection device and a trace gas detection method based on an intermediate infrared quantum cascade laser direct absorption spectrum method. A tunable quantum cascade laser serves as a light source, and concentration information of gas molecules to be measured is acquired by utilizing fundamental frequency fingerprint absorption characteristics of the gas molecules in an intermediate infrared wave band; the measured result is slightly influenced by light-intensity variation of the laser and has higher signal to noise ratio and certain anti-jamming capability by utilizing a direct absorption spectrum technology; and whether the measured gas contain expected gas components can be analyzed and determined by contrasting the measured spectrum with spectral line characteristics of corresponding gas in a HITRAN database, and concentration inversion is performed by utilizing spectral line parameters provided by the HITRAN database. The system is simple and compact in structure and convenient to use and maintain, has the characteristics of high measuring sensitivity, high accuracy and high response speed, can rapidly and accurately analyze and detect a plurality of trace gases and isotope ratios on line, and can be used for indicating and rapidly and accurately positioning intermediate infrared light spots.

Description

technical field [0001] The invention relates to a detection method of trace gas and a laser spectrum measuring device and method for gas analysis, which can continuously and rapidly measure extremely low concentration gas content, such as CH 4 , N 2 O, CO, NO and other gases (such low-concentration gases are generally referred to as trace gases), can also measure the concentration of gases containing stable isotopes, such as 13 CO 2 、H 2 18 O. 13 CH 4 , so it can also be used to measure the stable isotope ratio of carbon, hydrogen and oxygen ( 13 C / 12 C. 18 O / 16 O and D / H). Background technique [0002] Trace gas refers to the concentration in the atmosphere below 10 -6 Gases such as CO and N in the atmosphere 2 O, SO 2 , O 3 , NO, NO 2 、CH 4 , NH 3 、H 2 S, halides, organic compounds, etc. are all trace gases. They are affected by various physical, chemical, biological, and earth processes and participate in biogeochemical cycles, which have a significan...

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Problems solved by technology

However, research on stable isotope ratios started relatively late, mainly using imported sensors, and there is an urgent need to develop technical products and equipment with independent intellectual property rights

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