Development and Characterization of an Aircraft Aerosol Time-of-Flight Mass Spectrometer

Pratt, Kerri A.; Mayer, Joseph; Holecek, J. C.; Moffet, Ryan C.; Sanchez, Rene O.; Rebotier, Thomas P.; Furutani, Hiroshi; Gonin, Marc; Führer, Katrin; Su, Yongxuan; Guazzotti, S. A.; Prather, Kimberly A.

doi:10.1021/ac801942r

Cited by 111 publications

(127 citation statements)

References 35 publications

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“…Light collected over 10-170 • , which is similar to the collection angle of some elliptical mirrors (Pratt et al, 2009;Brands et al, 2011), produces a smoother profile with a lower particle size cut-off than the narrow angles represented by the LAAP-TOF detection system (Fig. 8b).…”

Section: Estimations Of the Effective Detection Beam Radiusmentioning

confidence: 80%

Evaluating the influence of laser wavelength and detection stage geometry on optical detection efficiency in a single-particle mass spectrometer

et al. 2016

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Abstract. Single-particle mass spectrometry (SPMS) is a useful tool for the online study of aerosols with the ability to measure size-resolved chemical composition with a temporal resolution relevant to atmospheric processes. In SPMS, optical particle detection is used for the effective temporal alignment of an ablation laser pulse with the presence of a particle in the ion source, and it gives the option of aerodynamic sizing by measuring the offset of particle arrival times between two detection stages. The efficiency of the optical detection stage has a strong influence on the overall instrument performance.A custom detection laser system consisting of a highpowered fibre-coupled Nd:YAG solid-state laser with a collimated beam was implemented in the detection stage of a laser ablation aerosol particle time-of-flight (LAAP-TOF) singleparticle mass spectrometer without major modifications to instrument geometry. The use of a collimated laser beam permitted the construction of a numerical model that predicts the effects of detection laser wavelength, output power, beam focussing characteristics, light collection angle, particle size, and refractive index on the effective detection radius (R) of the detection laser beam. We compare the model predictions with an ambient data set acquired during the Ice in Clouds Experiment -Dust (ICE-D) project.The new laser system resulted in an order-of-magnitude improvement in instrument sensitivity to spherical particles in the size range 500-800 nm compared to a focussed 405 nm laser diode system. The model demonstrates that the limit of detection in terms of particle size is determined by the scattering cross section (C sca ) as predicted by Mie theory. In addition, if light is collected over a narrow collection angle, oscillations in the magnitude of C sca with respect to particle diameter result in a variation in R, resulting in large particlesize-dependent variation in detection efficiency across the particle transmission range. This detection bias is imposed on the aerodynamic size distributions measured by the instrument and accounts for some of the detection bias towards sea salt particles in the ambient data set.

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Section: Estimations Of the Effective Detection Beam Radiusmentioning

confidence: 80%

Evaluating the influence of laser wavelength and detection stage geometry on optical detection efficiency in a single-particle mass spectrometer

et al. 2016

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“…Furthermore, analysis of discrete samples would likely make it possible to determine individual gas concentrations rather than their ratios (Machler et al, 2012;Visser et al, 2013). Building a vibration-isolating housing or support system for the mass spectrometer would improve the instrument's performance on ships and in other environments where vibrations are present (Aldrich et al, 1999;Volpe et al, 2001;Dubé et al, 2006;Pratt et al, 2009). …”

Section: Future Directionsmentioning

confidence: 99%

“…pneumatic vibration isolation platforms) to successfully isolate mass spectrometers and optical instruments from vibrations on ships and aircraft, (Pratt et al, 2009;Dubé et al, 2006;Volpe et al, 2001) and such an apparatus could potentially be used for the GEMS.…”

Section: A52 Data On a Moving Vessel And The Impact Of Vibration-inmentioning

confidence: 99%

Insight into chemical, biological, and physical processes in coastal waters from dissolved oxygen and inert gas tracers

Manning¹

2017

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In this thesis, I use coastal measurements of dissolved O 2 and inert gases to provide insight into the chemical, biological, and physical processes that impact the oceanic cycles of carbon and dissolved gases. Dissolved O 2 concentration and triple isotopic composition trace net and gross biological productivity. The saturation states of inert gases trace physical processes, such as air-water gas exchange, temperature change, and mixing, that affect all gases.First, I developed a field-deployable system that measures Ne, Ar, Kr, and Xe gas ratios in water. It has precision and accuracy of 1 % or better, enables near-continuous measurements, and has much lower cost compared to existing laboratory-based methods. The system will increase the scientific community's access to use dissolved noble gases as environmental tracers.Second, I measured O 2 and five noble gases during a cruise in Monterey Bay, California. I developed a vertical model and found that accurately parameterizing bubble-mediated gas exchange was necessary to accurately simulate the He and Ne measurements. I present the first comparison of multiple gas tracer, incubation, and sediment trap-based productivity estimates in the coastal ocean. Net community production estimated from 15 NO -3 uptake and O 2 /Ar gave equivalent results at steady state. Underway O 2 /Ar measurements revealed submesoscale variability that was not apparent from daily incubations.Third, I quantified productivity by O 2 mass balance and air-water gas exchange by dual tracer ( 3 He/SF 6 ) release during ice melt in the Bras d'Or Lakes, a Canadian estuary. The gas transfer velocity at >90 % ice cover was 6 % of the rate for nearly ice-free conditions. Rates of volumetric gross primary production were similar when the estuary was completely ice-covered and ice-free, and the ecosystem was on average net autotrophic during ice melt and net heterotrophic following ice melt. I present a method for incorporating the isotopic composition of H 2 O into the O 2 isotope-based productivity calculations, which increases the estimated gross primary production in this study by 46-97 %.In summary, I describe a new noble gas analysis system and apply O 2 and inert gas observations in new ways to study chemical, biological, and physical processes in coastal waters.

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“…In situ measurements of size-resolved chemical composition of individual submicron particles were made using the recently developed aircraft aerosol time-offlight mass spectrometer (A-ATOFMS) (Pratt et al 2009). The A-ATOFMS measures in real time the vacuum aerodynamic diameter d va and dual-polarity mass spectra of individual particles from ;70 to 1200 nm.…”

Section: B Aircraft Aerosol Time-of-flight Mass Spectrometermentioning

confidence: 99%

In Situ Chemical Characterization of Aged Biomass-Burning Aerosols Impacting Cold Wave Clouds

Pratt

Heymsfield

Twohy

et al. 2010

Journal of the Atmospheric Sciences

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During the Ice in Clouds Experiment-Layer Clouds (ICE-L), aged biomass-burning particles were identified within two orographic wave cloud regions over Wyoming using single-particle mass spectrometry and electron microscopy. Using a suite of instrumentation, particle chemistry was characterized in tandem with cloud microphysics. The aged biomass-burning particles comprised ;30%-40% by number of the 0.1-1.0-mm clear-air particles and were composed of potassium, organic carbon, elemental carbon, and sulfate. Aerosol mass spectrometry measurements suggested these cloud-processed particles were predominantly sulfate by mass. The first cloud region sampled was characterized by primarily homogeneously nucleated ice particles formed at temperatures near 2408C. The second cloud period was characterized by high cloud droplet concentrations (;150-300 cm 23) and lower heterogeneously nucleated ice concentrations (7-18 L 21) at cloud temperatures of 2248 to 2258C. As expected for the observed particle chemistry and dynamics of the observed wave clouds, few significant differences were observed between the clear-air particles and cloud residues. However, suggestive of a possible heterogeneous nucleation mechanism within the first cloud region, ice residues showed enrichments in the number fractions of soot and mass fractions of black carbon, measured by a single-particle mass spectrometer and a single-particle soot photometer, respectively. In addition, enrichment of biomass-burning particles internally mixed with oxalic acid in both the homogeneously nucleated ice and cloud droplets compared to clear air suggests either preferential activation as cloud condensation nuclei or aqueous phase cloud processing.

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Development and Characterization of an Aircraft Aerosol Time-of-Flight Mass Spectrometer

Cited by 111 publications

References 35 publications

Evaluating the influence of laser wavelength and detection stage geometry on optical detection efficiency in a single-particle mass spectrometer

Evaluating the influence of laser wavelength and detection stage geometry on optical detection efficiency in a single-particle mass spectrometer

Insight into chemical, biological, and physical processes in coastal waters from dissolved oxygen and inert gas tracers

In Situ Chemical Characterization of Aged Biomass-Burning Aerosols Impacting Cold Wave Clouds

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