Evaluation of the accuracy of thermal dissociation CRDS and LIF techniques for atmospheric measurement of reactive nitrogen species

Caroline C. Womack; J. Andrew Neuman; Patrick R. Veres; Scott J. Eilerman; Charles A. Brock; Zachary C.J. Decker; Kyle J. Zarzana; William P. Dube; Robert J. Wild; Paul J. Wooldridge; Ronald C. Cohen; Steven S. Brown

doi:10.5194/amt-10-1911-2017

Evaluation of the accuracy of thermal dissociation CRDS and LIF techniques for atmospheric measurement of reactive nitrogen species

Caroline C. Womack, J. Andrew Neuman, Patrick R. Veres, Scott J. Eilerman, Charles A. Brock, Zachary C.J. Decker, Kyle J. Zarzana, William P. Dube, Robert J. Wild, Paul J. Wooldridge, Ronald C. Cohen, Steven S. Brown

Experimental Science Section

Research output: Contribution to journal › Article › peer-review

17 Scopus citations

Abstract

The sum of all reactive nitrogen species (NOy) includes NOx (NO2ĝ€+ĝ€NO) and all of its oxidized forms, and the accurate detection of NOy is critical to understanding atmospheric nitrogen chemistry. Thermal dissociation (TD) inlets, which convert NOy to NO2 followed by NO2 detection, are frequently used in conjunction with techniques such as laser-induced fluorescence (LIF) and cavity ring-down spectroscopy (CRDS) to measure total NOy when set at >ĝ€600ĝ€°C or speciated NOy when set at intermediate temperatures. We report the conversion efficiency of known amounts of several representative NOy species to NO2 in our TD-CRDS instrument, under a variety of experimental conditions. We find that the conversion efficiency of HNO3 is highly sensitive to the flow rate and the residence time through the TD inlet as well as the presence of other species that may be present during ambient sampling, such as ozone (O3). Conversion of HNO3 at 400ĝ€°C, nominally the set point used to selectively convert organic nitrates, can range from 2 to 6ĝ€% and may represent an interference in measurement of organic nitrates under some conditions. The conversion efficiency is strongly dependent on the operating characteristics of individual quartz ovens and should be well calibrated prior to use in field sampling. We demonstrate quantitative conversion of both gas-phase N2O5 and particulate ammonium nitrate in the TD inlet at 650ĝ€°C, which is the temperature normally used for conversion of HNO3. N2O5 has two thermal dissociation steps, one at low temperature representing dissociation to NO2 and NO3 and one at high temperature representing dissociation of NO3, which produces exclusively NO2 and not NO. We also find a significant interference from partial conversion (5-10ĝ€%) of NH3 to NO at 650ĝ€°C in the presence of representative (50ĝ€ppbv) levels of O3 in dry zero air. Although this interference appears to be suppressed when sampling ambient air, we nevertheless recommend regular characterization of this interference using standard additions of NH3 to TD instruments that convert reactive nitrogen to NO or NO2.

Original language	English
Pages (from-to)	1911-1926
Number of pages	16
Journal	Atmospheric Measurement Techniques
Volume	10
Issue number	5
DOIs	https://doi.org/10.5194/amt-10-1911-2017
State	Published - May 31 2017

Access to Document

10.5194/amt-10-1911-2017

Cite this

Womack, C. C., Andrew Neuman, J., Veres, P. R., Eilerman, S. J., Brock, C. A., Decker, Z. C. J., Zarzana, K. J., Dube, W. P., Wild, R. J., Wooldridge, P. J., Cohen, R. C., & Brown, S. S. (2017). Evaluation of the accuracy of thermal dissociation CRDS and LIF techniques for atmospheric measurement of reactive nitrogen species. Atmospheric Measurement Techniques, 10(5), 1911-1926. https://doi.org/10.5194/amt-10-1911-2017

@article{83b5a9d85ebe4e75a337d2b5f687cc9b,

title = "Evaluation of the accuracy of thermal dissociation CRDS and LIF techniques for atmospheric measurement of reactive nitrogen species",

abstract = "The sum of all reactive nitrogen species (NOy) includes NOx (NO2ĝ€+ĝ€NO) and all of its oxidized forms, and the accurate detection of NOy is critical to understanding atmospheric nitrogen chemistry. Thermal dissociation (TD) inlets, which convert NOy to NO2 followed by NO2 detection, are frequently used in conjunction with techniques such as laser-induced fluorescence (LIF) and cavity ring-down spectroscopy (CRDS) to measure total NOy when set at >ĝ€600ĝ€°C or speciated NOy when set at intermediate temperatures. We report the conversion efficiency of known amounts of several representative NOy species to NO2 in our TD-CRDS instrument, under a variety of experimental conditions. We find that the conversion efficiency of HNO3 is highly sensitive to the flow rate and the residence time through the TD inlet as well as the presence of other species that may be present during ambient sampling, such as ozone (O3). Conversion of HNO3 at 400ĝ€°C, nominally the set point used to selectively convert organic nitrates, can range from 2 to 6ĝ€\% and may represent an interference in measurement of organic nitrates under some conditions. The conversion efficiency is strongly dependent on the operating characteristics of individual quartz ovens and should be well calibrated prior to use in field sampling. We demonstrate quantitative conversion of both gas-phase N2O5 and particulate ammonium nitrate in the TD inlet at 650ĝ€°C, which is the temperature normally used for conversion of HNO3. N2O5 has two thermal dissociation steps, one at low temperature representing dissociation to NO2 and NO3 and one at high temperature representing dissociation of NO3, which produces exclusively NO2 and not NO. We also find a significant interference from partial conversion (5-10ĝ€\%) of NH3 to NO at 650ĝ€°C in the presence of representative (50ĝ€ppbv) levels of O3 in dry zero air. Although this interference appears to be suppressed when sampling ambient air, we nevertheless recommend regular characterization of this interference using standard additions of NH3 to TD instruments that convert reactive nitrogen to NO or NO2.",

author = "Womack, \{Caroline C.\} and \{Andrew Neuman\}, J. and Veres, \{Patrick R.\} and Eilerman, \{Scott J.\} and Brock, \{Charles A.\} and Decker, \{Zachary C.J.\} and Zarzana, \{Kyle J.\} and Dube, \{William P.\} and Wild, \{Robert J.\} and Wooldridge, \{Paul J.\} and Cohen, \{Ronald C.\} and Brown, \{Steven S.\}",

year = "2017",

month = may,

day = "31",

doi = "10.5194/amt-10-1911-2017",

language = "English",

volume = "10",

pages = "1911--1926",

journal = "Atmospheric Measurement Techniques",

issn = "1867-1381",

publisher = "Copernicus Publications",

number = "5",

}

Womack, CC, Andrew Neuman, J, Veres, PR, Eilerman, SJ, Brock, CA, Decker, ZCJ, Zarzana, KJ, Dube, WP, Wild, RJ, Wooldridge, PJ, Cohen, RC & Brown, SS 2017, 'Evaluation of the accuracy of thermal dissociation CRDS and LIF techniques for atmospheric measurement of reactive nitrogen species', Atmospheric Measurement Techniques, vol. 10, no. 5, pp. 1911-1926. https://doi.org/10.5194/amt-10-1911-2017

TY - JOUR

T1 - Evaluation of the accuracy of thermal dissociation CRDS and LIF techniques for atmospheric measurement of reactive nitrogen species

AU - Womack, Caroline C.

AU - Andrew Neuman, J.

AU - Veres, Patrick R.

AU - Eilerman, Scott J.

AU - Brock, Charles A.

AU - Decker, Zachary C.J.

AU - Zarzana, Kyle J.

AU - Dube, William P.

AU - Wild, Robert J.

AU - Wooldridge, Paul J.

AU - Cohen, Ronald C.

AU - Brown, Steven S.

PY - 2017/5/31

Y1 - 2017/5/31

N2 - The sum of all reactive nitrogen species (NOy) includes NOx (NO2ĝ€+ĝ€NO) and all of its oxidized forms, and the accurate detection of NOy is critical to understanding atmospheric nitrogen chemistry. Thermal dissociation (TD) inlets, which convert NOy to NO2 followed by NO2 detection, are frequently used in conjunction with techniques such as laser-induced fluorescence (LIF) and cavity ring-down spectroscopy (CRDS) to measure total NOy when set at >ĝ€600ĝ€°C or speciated NOy when set at intermediate temperatures. We report the conversion efficiency of known amounts of several representative NOy species to NO2 in our TD-CRDS instrument, under a variety of experimental conditions. We find that the conversion efficiency of HNO3 is highly sensitive to the flow rate and the residence time through the TD inlet as well as the presence of other species that may be present during ambient sampling, such as ozone (O3). Conversion of HNO3 at 400ĝ€°C, nominally the set point used to selectively convert organic nitrates, can range from 2 to 6ĝ€% and may represent an interference in measurement of organic nitrates under some conditions. The conversion efficiency is strongly dependent on the operating characteristics of individual quartz ovens and should be well calibrated prior to use in field sampling. We demonstrate quantitative conversion of both gas-phase N2O5 and particulate ammonium nitrate in the TD inlet at 650ĝ€°C, which is the temperature normally used for conversion of HNO3. N2O5 has two thermal dissociation steps, one at low temperature representing dissociation to NO2 and NO3 and one at high temperature representing dissociation of NO3, which produces exclusively NO2 and not NO. We also find a significant interference from partial conversion (5-10ĝ€%) of NH3 to NO at 650ĝ€°C in the presence of representative (50ĝ€ppbv) levels of O3 in dry zero air. Although this interference appears to be suppressed when sampling ambient air, we nevertheless recommend regular characterization of this interference using standard additions of NH3 to TD instruments that convert reactive nitrogen to NO or NO2.

AB - The sum of all reactive nitrogen species (NOy) includes NOx (NO2ĝ€+ĝ€NO) and all of its oxidized forms, and the accurate detection of NOy is critical to understanding atmospheric nitrogen chemistry. Thermal dissociation (TD) inlets, which convert NOy to NO2 followed by NO2 detection, are frequently used in conjunction with techniques such as laser-induced fluorescence (LIF) and cavity ring-down spectroscopy (CRDS) to measure total NOy when set at >ĝ€600ĝ€°C or speciated NOy when set at intermediate temperatures. We report the conversion efficiency of known amounts of several representative NOy species to NO2 in our TD-CRDS instrument, under a variety of experimental conditions. We find that the conversion efficiency of HNO3 is highly sensitive to the flow rate and the residence time through the TD inlet as well as the presence of other species that may be present during ambient sampling, such as ozone (O3). Conversion of HNO3 at 400ĝ€°C, nominally the set point used to selectively convert organic nitrates, can range from 2 to 6ĝ€% and may represent an interference in measurement of organic nitrates under some conditions. The conversion efficiency is strongly dependent on the operating characteristics of individual quartz ovens and should be well calibrated prior to use in field sampling. We demonstrate quantitative conversion of both gas-phase N2O5 and particulate ammonium nitrate in the TD inlet at 650ĝ€°C, which is the temperature normally used for conversion of HNO3. N2O5 has two thermal dissociation steps, one at low temperature representing dissociation to NO2 and NO3 and one at high temperature representing dissociation of NO3, which produces exclusively NO2 and not NO. We also find a significant interference from partial conversion (5-10ĝ€%) of NH3 to NO at 650ĝ€°C in the presence of representative (50ĝ€ppbv) levels of O3 in dry zero air. Although this interference appears to be suppressed when sampling ambient air, we nevertheless recommend regular characterization of this interference using standard additions of NH3 to TD instruments that convert reactive nitrogen to NO or NO2.

UR - https://www.scopus.com/pages/publications/85019994523

U2 - 10.5194/amt-10-1911-2017

DO - 10.5194/amt-10-1911-2017

M3 - Article

AN - SCOPUS:85019994523

SN - 1867-1381

VL - 10

SP - 1911

EP - 1926

JO - Atmospheric Measurement Techniques

JF - Atmospheric Measurement Techniques

IS - 5

ER -

Evaluation of the accuracy of thermal dissociation CRDS and LIF techniques for atmospheric measurement of reactive nitrogen species

Abstract

Access to Document

Other files and links

Fingerprint

Cite this