Technology And Instrumentation Of Carbon Disulfide Detection With High Sensitivity Using A DFB-QCL

Carbon disulfide?CS₂?,a toxic and stinky pollutant with wide distribution,has strong band absorption spectrum features in the mid-infrared region.Carbon disulfide is not only harmful to the atmosphere,but also highly threating to both industrial safety and human health.In order to achieve accurate emission control of carbon disulfide and ensure the security of all aspects,it is urgent to develop high-precision and high-sensitivity detection method focusing on band spectrum to realize in site,real time and on line carbon disulfide monitoring.Firstly,a standard laser mount for unpacked distributed feedback quantum cascade laser?DFB-QCL?chip was designed,manufactured and tested.According to the high heating power of the QCL and the temperature controlling requirement in actual operation,the well-cooling laser mount was designed with three main modules as two-stage heatsink,laser holder and fine tuning collimation.Then the laser mount was manufactured and assembled,meanwhile,its effectiveness and stability was verified under laboratory.Secondly,two methods for carbon disulfide spectral detection were developed based on DFB-QCL.To begin with,the spectrum databases were used to analyze the interference from ambient air and common industrial pollutants,and the CS₂ spectrum features were screened.Then,on one hand,the differential optical absorption spectroscopy with DFB-QCL was applied to achieve simultaneous detection of CS₂with spectral interferents CO and N₂O,which was verified by mathematically analysis,simulation and experiments.On the other hand,the wavelength modulation absorption spectroscopy with DFB-QCL was applied to achieve specific detection of CS₂,and the modulation index optimizing and optical fringes removing were cautiously investigated to enable the wavelength modulation spectroscopy with band spectrum.Thirdly,the carbon disulfide online analyzer was developed based on the well-cooling QCL mount and the modulation absorption spectroscopy,and a series of experiments was designed to evaluate the analyzer performance such as linearity,noise,zero drift,detection limit and optimal integration time.In summary,the standard laser mount for DFB-QCL could provide stable temperature control in actual operation;and the differential optical absorption spectroscopy with DFB-QCL achieved simultaneous multi-component detection in the narrow spectral region of QCL,while the wavelength modulation spectroscopy with DFB-QCL achieved higher sensitivity and specificity in the CS₂ detection,so both of them are suitable and effective for sensitive and online CS₂ detection.Moreover,benefitting from the exquisite laser mount and optimized WMS with band spectrum,the carbon disulfide analyzer with high sensitivity and strong anti-interference capacity is promising for online carbon disulfide monitoring in complicated applications.