Industry
Hundt, P.M., Tuzson, B., Aseev, O., Liu, C., Scheidegger, P., Looser, H., Kapsalidis, F., Shahmohammadi, M., Faist, J., Emmenegger, L.
Appl. Phys. B 124, 108; 2018
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Instrumentation for environmental monitoring of gaseous pollutants and greenhouse gases tends to be complex, expensive, and energy demanding, because every
compound measured relies on a specific analytical technique. This work demonstrates an alternative approach based on mid-infrared laser absorption spectroscopy
with dual-wavelength quantum cascade lasers (QCLs). The combination of two dual- and one single-DFB QCL yields high-precision measurements of CO (0.08 ppb),
CO2 (100 ppb), NH3 (0.02 ppb), NO (0.4 ppb), NO2 (0.1 ppb), N2O (0.045 ppb), and O3 (0.11 ppb) simultaneously in a compact setup (45 × 45 cm2). The lasers are driven
time-multiplexed in intermittent continuous wave mode with a repetition rate of 1 kHz. The individual spectra are real-time averaged (1 s) by an FPGA-based data
acquisition system. The instrument was assessed for environmental monitoring and benchmarked with reference instrumentation to demonstrate its potential for
compact multi-species trace gas sensing.
Industry
L. Emmenegger , M. Hundt, M. Graf, P. Scheidegger, M. Müller, H. Looser and B. Tuzson
12th International Conference on Air Quality Science and Application, 18-22 May 2020; 2020
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Mid-IR spectroscopy using quantum cascade lasers (QCLs) allows sensitive, selective, and fast detection of air pollutants and greenhouse gases. Recent developments,
including dual-wavelength QCLs, create tantalizing options for compact, multispecies analysis in air quality monitoring and other environmental applications.
Air Quality Industry Science: Lab & Fields
Tillmann, R., Gkatzelis, G. I., Rohrer, F., Winter, B., Wesolek, C., Schuldt, T., Lange, A. C., Franke, P., Friese, E., Decker, M., Wegener, R., Hundt, M., Aseev, O., and Kiendler-Scharr, A.
Atmos. Meas. Tech., 15, 3827–3842; 2022
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A Zeppelin airship was used as a platform for in situ measurements of greenhouse gases and short-lived air pollutants within the planetary boundary layer
(PBL) in Germany. A novel quantum cascade laser-based multi-compound gas analyzer (MIRO Analytical AG) was deployed to simultaneously measure in situ
concentrations of greenhouse gases (CO2, N2O, H2O, and CH4) and air pollutants (CO, NO, NO2, O3, SO2, and NH3) with high precision at a measurement rate of
1 Hz. These measurements were complemented by electrochemical sensors for NO, NO2, O
x (NO2 + O3), and CO, an optical particle counter, temperature,
humidity, altitude, and position monitoring. Instruments were operated remotely without the need for on-site interactions. Three 2-week campaigns were
conducted in 2020 comprising commercial passenger as well as targeted flights over multiple German cities including Cologne, Mönchengladbach, Düsseldorf,
Aachen, Frankfurt, but also over industrial areas and highways.
Vertical profiles of trace gases were obtained during the airship landing and take-off. Diurnal variability of the Zeppelin vertical profiles was compared to
measurements from ground-based monitoring stations with a focus on nitrogen oxides and ozone. We find that their variability can be explained by the
increasing nocturnal boundary layer height from early morning towards midday, an increase in emissions during rush hour traffic, and the rapid photochemical
activity midday. Higher altitude (250–450 m) NO
x to CO ratios are further compared to the 2015 EDGAR emission inventory to find that pollutant concentrations
are influenced by transportation and residential emissions as well as manufacturing industries and construction activity. Finally, we report NO
x and CO
concentrations from one plume transect originating from a coal power plant and compare it to the EURopean Air pollution Dispersion-Inverse Modell (EURAD-
IM) model to find agreement within 15 %. However, due to the increased contribution of solar and wind energy and the impact of lockdown measures the
power plant was operating at max. 50 % capacity; therefore, possible overestimation of emissions by the model cannot be excluded.