The Measurement of Nitrophenols by Integrated Spectrum and TD-IBBCEAS

2020 ◽  
Author(s):  
Meng Wang ◽  
Jun Chen ◽  
Shengrong Lou ◽  
Dean Venables
Keyword(s):  
Thermal Decomposition ◽  
Cross Section ◽  
Absorption Spectroscopy ◽  
Brown Carbon ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy ◽  
Near Ultraviolet ◽  
Secondary Formation ◽  
The Cross ◽  
Primary Emissions

<p>Atmospheric Brown Carbon (BrC) is an important component of aerosol particles that Influences the climate through interactions with incoming solar and emitted terrestrial radiation. BrC can be generated from a variety of primary emissions (such as traffic, coal combustion, biomass burning) and secondary formation. Nitrophenols are classified as Brown Carbon due to their strong absorption in near-ultraviolet and visible regions.</p><p>A heated single path absorption spectroscopy system is been built to measure the cross section of nitrophenols. Due to its semi-volatility, the nitrophenols were introduced into the cell by N<sub>2</sub>. The cross section of nitrophenols is obtained by calculating the integrated absorption.</p><p>A Thermal Decomposition - Incoherent Broadband Cavity-Enhanced Absorption Spectroscopy (TD-IBBCEAS) system was setup for atmospheric measurement. This instrument covered the spectral region from 320 to 440nm which could contain the interested absorption of nitrophenols. A thermal decomposition device was used to heating the sample.  The system was characterized based in laboratory experiment.</p>

Spectrally resolved laboratory measurements of oxygen-oxygen collision induced absorption in the 308 – 495 nm range, including the 315, 328, and 421 nm bands

2020 ◽  
Author(s):  
Henning Finkenzeller ◽  
Rainer Volkamer
Keyword(s):  
Cross Section ◽  
Absorption Spectroscopy ◽  
Laboratory Measurements ◽  
Band Shape ◽  
Induced Absorption ◽  
Enhanced Absorption ◽  
Oxygen Oxygen ◽  
Analysis Scheme ◽  
The Cross ◽  
Spectrally Resolved

<p>Oxygen-oxygen collision induced absorption accounts for significant absorption of solar radiation in the atmosphere. It needs to be considered in the interpretation of spectra in absorption spectroscopy. If not represented correctly, it interferes in the retrieval of other trace gases. Quantitative measurements of oxygen-oxygen collision induced absorption, combined with the oxygen concentration vertical profile, allow to constrain radiative transfer processes in the atmosphere. No spectrally resolved cross section data of the bands below 335 nm wavelength and at 420 nm have been available. This study presents spectrally resolved gas-phase laboratory measurements of the oxygen-oxygen collision induced absorption in the ultraviolet and blue spectral range (308 – 495 nm), including the 315, 328, and 421 nm bands, acquired with Cavity Enhanced Absorption Spectroscopy under atmospherically relevant conditions. While the newly acquired data generally agree with existing data on the strong bands, significant differences consist in a higher signal to noise ratio, a non-zero baseline between bands, and a different band shape of the 344 nm band. This presentation discusses the laboratory setup and analysis scheme used to determine the cross section, and first applications of the cross section to atmospheric data sets.</p>

Sensitive Detection of Ambient Formaldehyde by Incoherent Broadband Cavity Enhanced Absorption Spectroscopy

2020 ◽  
Author(s):  
Jingwei Liu ◽  
Xin Li ◽  
Yiming Yang ◽  
Haichao Wang ◽  
Cailing Kuang ◽  
...  
Keyword(s):  
Light Intensity ◽  
Light Source ◽  
Absorption Spectroscopy ◽  
Fiber Bundle ◽  
Ambient Air ◽  
Optical Path ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy ◽  
Near Ultraviolet ◽  
Type Fiber

<p>Formaldehyde (HCHO) is the most abundant atmospheric carbonyl compound and plays an important role in the troposphere. However, HCHO detection via traditional incoherent broadband cavity enhanced absorption spectroscopy (IBBCEAS) is limited by short optical path lengths and weak light intensity. Thus, a new light-emitting diode (LED)-based IBBCEAS was developed herein to measure HCHO in ambient air. Two LEDs (325 and 340 nm) coupled by a Y-type fiber bundle were used as an IBBCEAS light source, which provided both high light intensity and a wide spectral fitting range. The reflectivity of the two cavity mirrors used herein was 0.99965 (1 – reflectivity = 350 ppm loss) at 350 nm, which corresponded with an effective optical path length of 2.15 km within a 0.84 m cavity. At an integration time of 30 s, the measurement precision (1σ) for HCHO was 380 parts per trillion volume (pptv) and the corresponding uncertainty was 8.3%. The instrument was successfully deployed for the first time in a field campaign and delivered results that correlated well with those of a commercial wet-chemical instrument based on Hantzsch fluorimetry (R<sup>2</sup> = 0.769). The combined light source based on Y-type fiber bundle overcomes the difficulty of measuring ambient HCHO via IBBCEAS in near-ultraviolet range, which may extend IBBCEAS technology to measure other atmospheric trace gases with high precision.</p>

Near‐ultraviolet Incoherent Broadband Cavity Enhanced Absorption Spectroscopy for OClO and CH2O in Cl‐initiated Photooxidation Experiment

2013 ◽  
Vol 26 (2) ◽  
pp. 133-139 ◽  
Author(s):  
Mei‐li Dong ◽  
Wei‐xiong Zhao ◽  
Ming‐qiang Huang ◽  
Wei‐dong Chen ◽  
Chang‐jin Hu ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy ◽  
Near Ultraviolet

scholarly journals Quantification of nitrous acid (HONO) and nitrogen dioxide (NO<sub>2</sub>) in ambient air by broadband cavity-enhanced absorption spectroscopy (IBBCEAS) between 361–388 nm

2019 ◽  
Author(s):  
Nick Jordan ◽  
Hans D. Osthoff
Keyword(s):  
Absorption Spectroscopy ◽  
Optical Cavity ◽  
Ambient Air ◽  
Acquisition Time ◽  
Optical Extinction ◽  
Mixing Ratios ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy ◽  
Near Ultraviolet ◽  
Mirror Reflectivity

Abstract. This work describes a state-of-the-art, incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) instrument for quantification of HONO and NO2 mixing ratios in ambient air. The instrument is operated in the near-ultraviolet spectral region between 361 and 388 nm. The mirror reflectivity and optical cavity transmission function were determined from the optical extinction observed when sampling air and helium. To verify the accuracy of this approach, Rayleigh scattering cross-sections of nitrogen and argon were measured and found in quantitative agreement with literature values. The mirror reflectivity exceeded 99.98 %, at its maximum near 373 nm, resulting in an absorption pathlength of 6 km from a 1 m long optical cavity. The instrument precision was assessed through Allan variance analyses and showed minimum deviations of &amp;pm;58 pptv and &amp;pm;210 pptv (1σ) for HONO and NO2, respectively, at an optimum acquisition time of 5 min. Measurements of HONO and NO2 mixing ratios in laboratory-generated mixtures by IBBCEAS were compared to thermal dissociation cavity ring-down spectroscopy (TD-CRDS) data and agreed within combined experimental uncertainties. Sample ambient air data collected in Calgary are presented.

scholarly journals Quantification of nitrous acid (HONO) and nitrogen dioxide (NO<sub>2</sub>) in ambient air by broadband cavity-enhanced absorption spectroscopy (IBBCEAS) between 361 and 388 nm

2020 ◽  
Vol 13 (1) ◽  
pp. 273-285 ◽  
Author(s):  
Nick Jordan ◽  
Hans D. Osthoff
Keyword(s):  
Absorption Spectroscopy ◽  
Optical Cavity ◽  
Ambient Air ◽  
Acquisition Time ◽  
Optical Extinction ◽  
Mixing Ratios ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy ◽  
Near Ultraviolet ◽  
Mirror Reflectivity

Abstract. This work describes an incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) instrument for quantification of HONO and NO2 mixing ratios in ambient air. The instrument is operated in the near-ultraviolet spectral region between 361 and 388 nm. The mirror reflectivity and optical cavity transmission function were determined from the optical extinction observed when sampling air and helium. To verify the accuracy of this approach, Rayleigh scattering cross sections of nitrogen and argon were measured and found to be in quantitative agreement with literature values. The mirror reflectivity exceeded 99.98 %, at its maximum near 373 nm, resulting in an absorption path length of 6 km from a 1 m long optical cavity. The instrument precision was assessed through Allan variance analyses and showed minimum deviations of ±58 and ±210 pptv (1σ) for HONO and NO2, respectively, at an optimum acquisition time of 5 min. Measurements of HONO and NO2 mixing ratios in laboratory-generated mixtures by IBBCEAS were compared to thermal dissociation cavity ring-down spectroscopy (TD-CRDS) data and agreed within combined experimental uncertainties. Sample ambient air data collected in Calgary are presented.

Incoherent Broadband Cavity-Enhanced Absorption Spectroscopy in the near-Ultraviolet: Application to HONO and NO2

2008 ◽  
Vol 42 (3) ◽  
pp. 890-895 ◽  
Author(s):  
Titus Gherman ◽  
Dean S. Venables ◽  
Stewart Vaughan ◽  
Johannes Orphal ◽  
Albert A. Ruth
Keyword(s):  
Absorption Spectroscopy ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy ◽  
Near Ultraviolet

scholarly journals A broadband optical cavity spectrometer for measuring weak near-ultraviolet absorption spectra of gases

2011 ◽  
Vol 4 (3) ◽  
pp. 425-436 ◽  
Author(s):  
J. Chen ◽  
D. S. Venables
Keyword(s):  
Absorption Spectra ◽  
Cross Sections ◽  
Optical Cavity ◽  
Absorption Cross ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy ◽  
Near Ultraviolet ◽  
Low Concentrations ◽  
Measured Absorption ◽  
Atmospheric Observations

Abstract. Accurate absorption spectra of gases in the near–ultraviolet (300 to 400 nm) are essential in atmospheric observations and laboratory studies. This paper describes a novel incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) instrument for measuring very weak absorption spectra from 335 to 375 nm. The instrument performance was validated against the 3B1-X1A1 transition of SO2. The measured absorption varied linearly with SO2 column density and the resulting spectrum agrees well with published spectra. Using the instrument, we report new absorption cross-sections of O3, acetone, 2-butanone, and 2-pentanone in this spectral region, where literature data diverge considerably. In the absorption minimum between the Huggins and Chappuis bands, our absorption spectra fall at the lower range of reported ozone absorption cross-sections. The spectra of the ketones agree with prior spectra at moderate absorptions, but differ significantly at the limits of other instruments' sensitivity. The collision-induced absorption of the O4 dimer at 360.5 nm was also measured and found to have a maximum cross-section of ca. 4.0×10−46 cm5 molecule−2. We demonstrate the application of the instrument to quantifying low concentrations of the short-lived radical, BrO, in the presence of stronger absorptions from Br2 and O3.

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