Development Of High Sensitivity Acetonitrile Sensor Using A DFB-ICL

Acetonitrile（CH₃CN）is a kind of volatile and combustible toxic substance,which harmful to industrial safety and human health.Based on the demand of gas phase acetonitrile detection in production and daily life,it is necessary to develop a highly sensitive on-line detection sensor.High quality spectral data is also necessary to ensure the high accuracy of the sensor.The main works of this thesis are summarized as follow:First,the method of on-line spectral measuring instrument response function correction based on extended internal standard is proposed and validated for the first time,in which methane（CH₄）was used as a standard substance in the CH₃CN sample,and the linear form of CH₄ absorption spectrum was used as the correction standard to correct multi-dimensional correction of the signal,so as to solve the influence of non-linearity of detector and signal channel,baseline drift and various interference in the signal.This method not only simplifies the calibration process,but also improves the spectral accuracy further and realizes the calibration of multiple measurement parameters by a standard substance.Second,the high-resolution and-precision direct absorption spectrum of acetonitrile in v₅-band were measured for the first time.The spectral measurement system based on TLAS technology was constructed,and the influencing factors of spectral resolution and accuracy were analyzed and optimized.In this thesis,the high-resolution and-precision direct absorption spectrum of CH₃CN based on air broadening was finally obtained,and the spectral accuracy up to 10E-4,the spectral resolution was calculated to be 2.15×10^-5 cm^-1（23 fm/637 kHz）,the uncertainty of absorption cross section was 1.1%.The experimental results make up for the spectrum data vacancy of CH₃CN in the v₅-band.Third,the mid-infrared gas phase CH₃CN sensor was developed.The mixed signals of acetonitrile,methane and water in the air were obtained based on the WMS method,and the concentration of each gas component was determined by multispectral fitting.The various parameters of the sensor were evaluated.the detection limit of the sensor could reach 2.75 ppb,and corresponding absorbance was 3.95E-6.The simultaneous measurement of gas phase acetonitrile,methane and water in atmospheric environment was studied.In this thesis,the high-resolution and-precision direct absorption spectra of acetonitrile under air broadening of v₅-band are measured with using TLAS technology.Meanwhile,it is also the first time that an extended internal standard method is proposed to correct the non-linearity and deviation in the signal,and a good effect is obtained.The sensor which can simultaneously measure the concentration of acetonitrile,water and methane in atmosphere is developed and evaluated by using WMS technology combined with multispectral fitting method.Modified acetonitrile spectral data can provide high quality standard data for acetonitrile sensor and other related researches,and the developed multi-component gas sensor based on mid-infrared can simultaneously measure acetonitrile,methane and water in atmospheric environment with high sensitivity and low detection limit.