Sample introduction and pressure measuring system for chemical ionization mass spectrometers

1981 ◽  
Vol 53 (9) ◽  
pp. 1551-1552 ◽  
Author(s):  
A. J. Illies ◽  
M. T. Bowers ◽  
G. G. Meisels
Keyword(s):  
Chemical Ionization ◽  
Sample Introduction ◽  
Measuring System ◽  
Ionization Mass ◽  
Mass Spectrometers

scholarly journals Ternary homogeneous nucleation of H<sub>2</sub>SO<sub>4</sub>, NH<sub>3</sub>, and H<sub>2</sub>O under conditions relevant to the lower troposphere

2011 ◽  
Vol 11 (10) ◽  
pp. 4755-4766 ◽  
Author(s):  
D. R. Benson ◽  
J. H. Yu ◽  
A. Markovich ◽  
S.-H. Lee
Keyword(s):  
Homogeneous Nucleation ◽  
Chemical Ionization ◽  
Lower Troposphere ◽  
Global Scale ◽  
Ionization Mass ◽  
Aerosol Formation ◽  
Laboratory Measurements ◽  
Mass Spectrometers ◽  
Water Condensation ◽  
Atmospheric Observations

Abstract. Ternary homogeneous nucleation (THN) of H2SO4, NH3 and H2O has been used to explain new particle formation in various atmospheric regions, yet laboratory measurements of THN have failed to reproduce atmospheric observations. Here, we report first laboratory observations of THN made under conditions relevant to the lower troposphere ([H2SO4] of 106–107 cm−3, [NH3] of 0.08–20 ppbv, and a temperature of 288 K). Our observations show that NH3 can enhance atmospheric H2SO4 aerosol nucleation and the enhancement factor (EF) in nucleation rate (J) due to NH3 (the ratio of J measured with vs. without NH3) increases linearly with increasing [NH3] and increases with decreasing [H2SO4] and RH. Two chemical ionization mass spectrometers (CIMS) are used to measure [H2SO4] and [NH3], as well as possible impurities of amines in the nucleation system. Aerosol number concentrations are measured with a water condensation counter (CPC, TSI 3786). The slopes of Log J vs. Log [H2SO4], Log J vs. Log RH, and Log J vs. Log [NH3] are 3–5, 1–4, and 1, respectively. These slopes and the threshold of [H2SO4] required for the unity nucleation vary only fractionally in the presence and absence of NH3. These observations can be used to improve aerosol nucleation models to assess how man-made SO2 and NH3 affect aerosol formation and CCN production at the global scale.

scholarly journals Measurement of iodine species and sulfuric acid using bromide chemical ionization mass spectrometers

2020 ◽  
Author(s):  
Mingyi Wang ◽  
Xu-Cheng He ◽  
Henning Finkenzeller ◽  
Siddharth Iyer ◽  
Dexian Chen ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Chemical Ionization ◽  
Detection Limits ◽  
Particle Formation ◽  
Cloud Chamber ◽  
Ionization Mass ◽  
New Particle Formation ◽  
Reduced Pressure ◽  
Mass Spectrometers ◽  
Iodine Species

Abstract. Iodine species are important in the marine atmosphere for oxidation and new-particle formation. Understanding iodine chemistry and iodine new-particle formation requires high time resolution, high sensitivity, and simultaneous measurements of many iodine species. Here, we describe the application of bromide chemical ionization mass spectrometers (Br-CIMS) to this task. During iodine new-particle formation experiments in the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber, we have measured gas-phase iodine species and sulfuric acid using two Br-CIMS, one coupled to a Multi-scheme chemical IONization inlet (Br-MION-CIMS) and the other to a Filter Inlet for Gasses and AEROsols inlet (Br-FIGAERO-CIMS). From offline calibrations and inter-comparisons with other instruments attached to the CLOUD chamber, we have quantified the sensitivities of the Br-MION-CIMS to HOI, I2, and H2SO4 and obtain detection limits of 5.8 × 106, 6.3 × 105, and 2.0 × 105 molec cm−3, respectively, for a 2-min integration time. From binding energy calculations, we estimate the detection limit for HIO3 to be 1.2 × 105 molec cm−3, based on an assumption of maximum sensitivity. Detection limits in the Br-FIGAERO-CIMS are around one order of magnitude higher than those in the Br-MION-CIMS; for example, the detection limits for HOI and HIO3 are 3.3 × 107 and 5.1 × 106 molec cm−3, respectively. Our comparisons of the performance of the MION inlet and the FIGAERO inlet show that bromide chemical ionization mass spectrometers using either atmospheric pressure or reduced pressure interfaces are well-matched to measuring iodine species and sulfuric acid in marine environments.

scholarly journals Measurement of iodine species and sulfuric acid using bromide chemical ionization mass spectrometers

2021 ◽  
Vol 14 (6) ◽  
pp. 4187-4202
Author(s):  
Mingyi Wang ◽  
Xu-Cheng He ◽  
Henning Finkenzeller ◽  
Siddharth Iyer ◽  
Dexian Chen ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Chemical Ionization ◽  
Detection Limits ◽  
Particle Formation ◽  
High Time Resolution ◽  
Ionization Mass ◽  
New Particle Formation ◽  
Reduced Pressure ◽  
Mass Spectrometers ◽  
Iodine Species

Abstract. Iodine species are important in the marine atmosphere for oxidation and new-particle formation. Understanding iodine chemistry and iodine new-particle formation requires high time resolution, high sensitivity, and simultaneous measurements of many iodine species. Here, we describe the application of a bromide chemical ionization mass spectrometer (Br-CIMS) to this task. During the iodine oxidation experiments in the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber, we have measured gas-phase iodine species and sulfuric acid using two Br-CIMS, one coupled to a Multi-scheme chemical IONization inlet (Br-MION-CIMS) and the other to a Filter Inlet for Gasses and AEROsols inlet (Br-FIGAERO-CIMS). From offline calibrations and intercomparisons with other instruments, we have quantified the sensitivities of the Br-MION-CIMS to HOI, I2, and H2SO4 and obtained detection limits of 5.8 × 106, 3.8 × 105, and 2.0 × 105 molec. cm−3, respectively, for a 2 min integration time. From binding energy calculations, we estimate the detection limit for HIO3 to be 1.2 × 105 molec. cm−3, based on an assumption of maximum sensitivity. Detection limits in the Br-FIGAERO-CIMS are around 1 order of magnitude higher than those in the Br-MION-CIMS; for example, the detection limits for HOI and HIO3 are 3.3 × 107 and 5.1 × 106 molec. cm−3, respectively. Our comparisons of the performance of the MION inlet and the FIGAERO inlet show that bromide chemical ionization mass spectrometers using either atmospheric pressure or reduced pressure interfaces are well-matched to measuring iodine species and sulfuric acid in marine environments.

scholarly journals A low-activity ion source for measurement of atmospheric gases by chemical ionization mass spectrometry

2020 ◽  
Vol 13 (5) ◽  
pp. 2473-2480 ◽  
Author(s):  
Young Ro Lee ◽  
Yi Ji ◽  
David J. Tanner ◽  
L. Gregory Huey
Keyword(s):  
Gas Flow ◽  
Chemical Ionization ◽  
Ion Source ◽  
Ionization Mass ◽  
Gas Flows ◽  
Initial Activity ◽  
Mass Spectrometers ◽  
Carrier Gas ◽  
Standard Source ◽  
Low Activity

Abstract. Most I−-CIMSs (iodide chemical ionization mass spectrometers) for measurement of atmospheric trace gases utilize a radioactive ion source with an initial activity of 10 or 20 mCi of 210Po. In this work, we characterize a 210Po ion source with an initial activity of 1.5 mCi that can be easily constructed from commercially available components. The low level of radioactive activity of this source significantly reduces regulatory burden with storage and shipping relative to higher-activity sources. We compare the sensitivity of the low-activity source (LAS) to a standard 20 mCi source, as a function of carrier gas flow and flow tube pressure, for peroxyacetyl nitrate (PAN), formic acid (HCO2H), molecular chlorine (Cl2) and nitryl chloride (ClNO2), using an I−-CIMS. The LAS provides 2 to 5 times less sensitivity than that of the standard source even though the ratio of activity is approximately 13. However, detection limits of less than 2 pptv for the tested compounds are achieved for integration times on the order of a minute. The sensitivity of the LAS is less dependent on the magnitude of the carrier gas than a standard source. In addition, the LAS provides maximum sensitivity at relatively low carrier gas flows. Finally, we demonstrate that the LAS can be used to measure PAN in the remote atmosphere from an aircraft by showing data obtained on the NASA DC-8 during the Atmospheric Tomography (ATom) mission. In summary, the LAS may be an excellent substitute for a standard ion source in short-term field deployments.

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