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A Demonstration of Broadband Cavity-Enhanced Absorption Spectroscopy at Deep-Ultraviolet Wavelengths: Application to Sensitive Real-Time Detection of the Aromatic Pollutants Benzene, Toluene, and Xylene
journal contribution
posted on 2022-03-04, 20:03 authored by Meng Wang, Ravi Varma, Dean S. Venables, Wu Zhou, Jun ChenBenzene, toluene,
and xylene (BTX) are serious air pollutants emitted
by the chemical industry. Real-time monitoring of these air pollutants
would be a valuable tool to regulate emissions of these compounds
and reduce the harm they cause to human health. Here, we demonstrate
the first detection of BTX using incoherent broadband cavity-enhanced
absorption spectroscopy (IBBCEAS). The instrument was operated in
the deep-ultraviolet spectral region between 252 and 286 nm, where
aromatic compounds have intense π → π* absorption
bands. The mirror reflectivity was calibrated by two methods and exceeded
99.63% at 266 nm. At an integration time of 60 s, the 1σ measurement
sensitivities were estimated to be 7.2 ppbv for benzene, 21.9 ppbv
for toluene, 10.2 ppbv for m-xylene, and 4.8 ppbv
for p-xylene, respectively. The absorption cross
sections of BTX were measured in this work with an uncertainty of
10.0% at a resolution of 0.74 nm. The absorption cross sections reported
in this work were in good agreement with those from earlier studies
after accounting for differences in spectral resolution. To demonstrate
the ability of the instrument to quantify complex mixtures, the concentrations
of m-xylene and p-xylene have been
retrieved under five different mixing ratios. Instrumental improvements
and measurements strategies for use in different applications are
discussed.
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quantify complex mixturesair pollutants would1σ measurement sensitivitiesenhanced absorption spectroscopyabsorption cross sectionsultraviolet spectral regionaromatic pollutants benzeneabsorption bandsultraviolet wavelengthsvaluable tooltwo methodstime monitoringtime detectionspectral resolutionregulate emissionsmirror reflectivitymeasurements strategiesintegration timeinstrumental improvementsibbceas ).human healthgood agreementfirst detectionexceeded 99earlier studiesdifferent applicationschemical industrybroadband cavityaromatic compounds9 ppbv8 ppbv74 nm286 nm266 nm2 ppbv