Abstract
A compact gas sensor system based on quartz-enhanced photoacoustic spectroscopy (QEPAS) employing a continuous wave (CW) distributed feedback quantum cascade laser (DFB-QCL) operating at 4.59 µm was developed for detection of carbon disulfide (CS2) in air at trace concentration. The influence of water vapor on monitored QEPAS signal was investigated to enable compensation of this dependence by independent moisture sensing. A 1 σ limit of detection of 28 parts per billion by volume (ppbv) for a 1 s lock-in amplifier time constant was obtained for the CS2 line centered at 2178.69 cm-1 when the gas sample was moisturized with 2.3 vol% H2O. The work reports the suitability of the system for monitoring CS2 with high selectivity and sensitivity, as well as low sample gas volume requirements and fast sensor response for applications such as workplace air and process monitoring at industry.
Highlights
Carbon disulfide (CS2) is being used as a raw material in a variety of industrial applications, at which the production of regenerated cellulose in form of rayon fibers and cellophane is the dominant industrial use, accounting for three-fourth of the total demand [1]
The United States regulatory permissible exposure limit (PEL) value of CS2 directed by the Occupational Safety and Health Administration (OSHA) is 20 ppm expressed as a timeweighted average for an 8-hour workshift of a 40-hour workweek
The sensitivity of the quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor is a function of the gas pressure p and the Quantum cascade lasers (QCLs) wavelength modulation depth m
Summary
Carbon disulfide (CS2) is being used as a raw material in a variety of industrial applications, at which the production of regenerated cellulose in form of rayon fibers and cellophane is the dominant industrial use, accounting for three-fourth of the total demand [1]. Quartz-enhanced photoacoustic spectroscopy (QEPAS) is a very powerful technique that allows selective and sensitive measurements of trace gases in an ultra-small acoustic detection module (ADM) with a total sample volume of only a few mm3 [8]. The principle of this technique is based on the photoacoustic (PA) effect, where the absorption of modulated laser radiation by gas molecules causes a periodic heating of the chemical species. A compact and robust sensor system is presented, capable for continuous monitoring of this molecule in an industrial environment
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