Intermediate infrared absorption spectra based method for multi-component mixed gas qualitative and quantitative analysis and system thereof

Abstract

The invention belongs to the technical field of optics, and particularly relates to an intermediate infrared absorption spectra based method for multi-component mixed gas qualitative and quantitative analysis and a system thereof. The method provided by the invention includes the steps as follows: a nonlinear optimization method is adopted, repeated fitting for the characteristic absorption spectra is performed through adopting a series of Voigt functions, so as to judge the absorption peaks of to-be-tested gases for forming the tested absorption peak, and further obtain a list of peak positions; default positions of peak values of spectra of different objects obtained from a standard data bank are compared with the peak positions in the list, so that the existence of a certain gas can beconfirmed within a certain acceptable error range; and the gas concentration can be acquired through the nonlinear optimization algorithm carried out by the computer. The method provided by the invention can obtain an accurate result through numerical analysis even if positions of spectrum lines or line widths tested by an instrument change to a certain extent under the influence of an environment, and does not need an independent spectrometer to obtain reference spectra under different experiment conditions; and meanwhile, the invention provides the system for realizing the method for the qualitative and quantitative analysis.

Description

technical field [0001] The invention belongs to the field of optical technology, in particular to a method and system for qualitative and quantitative analysis of multi-component mixed gas based on mid-infrared absorption spectrum. Background technique [0002] Since the rotational and vibrational energy states of gas molecules in the mid-infrared band can produce strong characteristic absorption spectra, tunable mid-infrared quantum cascade laser (Quantum Cascade laser, QCL) spectroscopy is widely used in the field of atmospheric trace gas monitoring. [0003] Beer's law relates the electrical signal output from the MCT detector to the gas concentration and its corresponding molecular spectrum. [0004] Due to the limitations of the tuning range and spectral resolution of quantum cascade lasers, a variety of numerical fitting methods were used to quantitatively analyze the gas concentration in the monitored spectrum. [0005] The widely used linear least squares fitting me...

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Problems solved by technology

[0006]1. Unable to qualitatively analyze the spectrum containing unknown gas, it is necessary to manually input the gas that may exist, and then analyze the type of gas that may exist under a specific environmental condition The absorption spectra obtained by a separate spectrometer are linearly weighted and summed to obtain the concentration of the corresponding gas species

[0007]2. There is a large inaccuracy in the quantitative analysis of gas concentration

That is, when the experimental conditions are far away from normal temperature and pressure, due to the influence of peak position shift and peak width change on the absorption spectrum, the gas concentration results obtained by the CLS method will have a large error

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