A compact incoherent broadband cavity-enhanced absorption spectrometer for trace detection of nitrogen oxides, iodine oxide and glyoxal at levels below parts per billion for field applications

Abstract

Abstract. We present a compact, affordable and robust instrument based on incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) for simultaneous detection of NOx, IO, CHOCHO and O3 in the 400–475 nm wavelength region. The instrument relies on the injection of a high-power LED source in a high-finesse cavity (F∼33 100), with the transmission signal being detected by a compact spectrometer based on a high-order diffraction grating and a charge-coupled device (CCD) camera. A minimum detectable absorption of 2.0×10-10 cm−1 was achieved within ∼22 min of total acquisition, corresponding to a figure of merit of 1.8×10-10 cm−1 Hz-1/2 per spectral element. Due to the multiplexing broadband feature of the setup, multi-species detection can be performed with simultaneous detection of NO2, IO, CHOCHO and O3 achieving detection limits of 11, 0.3, 10 ppt (parts per trillion) and 47 ppb (parts per billion) (1σ) within 22 min of measurement, respectively (half of the time is spent on the acquisition of the reference spectrum in the absence of the absorber, and the other half is spent on the absorption spectrum). The implementation on the inlet gas line of a compact ozone generator based on electrolysis of water allows for the measurement of NOx (NO+NO2) and therefore an indirect detection of NO with detection limits for NOx and NO of 10 and 21 ppt (1σ), respectively. The device has been designed to fit in a 19 in., 3U (5.25 in.) rack-mount case; weighs 15 kg; and has a total electrical power consumption of <300 W. The instrument can be employed to address different scientific objectives such as better constraining the oxidative capacity of the atmosphere, studying the chemistry of highly reactive species in atmospheric chambers as well as in the field and looking at the sources of glyoxal in the marine boundary layer to study possible implications on the formation of secondary aerosol particles.

New Estimation of the NOx Snow‐Source on the Antarctic Plateau

“…range, with a slope of 1.015  E 0.006 and a correlation factor of 2 R E = 0.9996 (Barbero et al, 2020). Field calibrations were made using a…”

Summer variability of the atmospheric NO2:NO ratio at Dome C, on the East Antarctic Plateau

“…fractions up to 8 ppmv were used, and, applied O 3 mole fractions were kept below 6 ppmv (5.6 ± 1.5 and 4.3 ± 0.5 ppmv in December and January, respectively) during this field study. Ultimate detection limits of 33 and 63 pptv (3σ) for NO x and NO (taking into account the propagation error), respectively, are also achieved within ≈ 20 min of measurement (Barbero et al, 2020), according to an Allan-Werle statistical method (Werle et al, 1993). The instruments were calibrated prior and after field deployment using a stable reference NO 2 source (FlexStream TM Gas Standards Generator, KINTEK Analytical, Inc.), covering a large range of concentrations from the pptv to ppbv range (Barbero et al, 2020).…”

“…The twin instruments described in Barbero et al (2020) were used for NO x detection in the 400-475 nm wavelength region. These instruments are based on incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) with a high-power LED source injected in a high-finesse cavity (F ≈ 33,100), and the transmission signal is detected by a compact spectrometer equipped with a charge-coupled device (CCD) camera.…”

Thermal dissociation cavity-enhanced absorption spectrometer for measuring NO<sub>2</sub>, RO<sub>2</sub>NO<sub>2</sub>, and RONO<sub>2</sub> in the atmosphere

“…They are closely related to the distribution of oxidants in the atmosphere by terminating the HO x cycle. ONs are also important precursors of secondary organic aerosols (SOAs) (Berkemeier et al, 2016;Lee et al, 2016;Ng et al, 2017;Rollins et al, 2012). Volatile organic compounds (VOCs) are oxidized by OH or O 3 to produce peroxy radicals (RO 2 ), and then RO 2 reacts with NO 2 to produce PNs (Reaction R1).…”

“…TD-CRDS and TD-CAPS show high spatial and temporal resolution and good measurement capability (Sadanaga et al, 2016;Sobanski et al, 2016). CEAS (cavity-enhanced absorption spectroscopy) is a powerful technology that can monitor several compounds or species simultaneously with broad absorption bands being detected (Fiedler et al, 2003) and has been applied to measure many species in field studies, such as NO 2 , HONO, NO 3 , N 2 O 5 , IO, glyoxal, and methylglyoxal (Ball et al, 2004;Barbero et al, 2020;Duan et al, 2018;Gherman et al, 2008;Jordan and Osthoff, 2020;Kahan et al, 2012;Langridge et al, 2006;Lechevallier et al, 2019;Liu et al, 2019;Min et al, 2016;Thalman and Volkamer, 2010;Vaughan et al, 2008;Venables et al, 2006;Ventrillard-Courtillot et al, 2010;Ventrillard et al, 2017;Washenfelder et al, 2016Washenfelder et al, , 2008Watt et al, 2009). Organic nitrates have a large range of mixing ratios in the atmosphere that vary from several pptv in warm and remote regions to several parts per billion by volume (ppbv) in polluted regions.…”