Generating Particle Beams of Controlled Dimensions and Divergence: I. Theory of Particle Motion in Aerodynamic Lenses and Nozzle Expansions

Liu, Peng; Ziemann, Paul J.; Kittelson, David B.; McMurry, Peter H.

doi:10.1080/02786829408959748

Cited by 504 publications

(429 citation statements)

References 21 publications

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“…Ambient-pressure sample containing aerosol particles enters the instrument through a 130 mm critical orifice, after which particles are collimated using the aerodynamic focusing lens mentioned above [Liu et al, 1995a[Liu et al, , 1995b. Because of the transmission efficiency of this lens, the Q-AMS measures particles with vacuum aerodynamic diameters (D va ) between 40 nm and 1 mm; this measurement is typically referred to as submicron [Liu et al, 1995a[Liu et al, , 1995bJayne et al, 2000;Allan et al, 2003], although the range of 100% transmission of particles is 60 to 600 nm. No correction was applied to account for sub-100% transmission of particles with diameters smaller than 60 and greater than 600 nm.…”

Section: Measurementsmentioning

confidence: 99%

Characterization of aerosol associated with enhanced small particle number concentrations in a suburban forested environment

Ziemba¹,

Griffin²,

Cottrell³

et al. 2010

J. Geophys. Res.

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Two elevated particle number/mass growth events associated with Aitken‐mode particles were observed during a sampling campaign (13–29 September 2004) at the Duke University Free‐Air CO2 Enrichment facility, a forested field site located in suburban central North Carolina. Aerosol growth rates between 1.2 and 4.9 nm hr−1 were observed, resulting in net increases in geometric mean diameter of 21 and 37 nm during events. Growth was dominated by addition of oxidized organic compounds. Campaign‐average aerosol mass concentrations measured by an Aerodyne quadrupole aerosol mass spectrometer (Q‐AMS) were 1.9 ± 1.6 (σ), 1.6 ± 1.9, 0.1 ± 0.1, and 0.4 ± 0.4 μg m−3 for organic mass (OM), sulfate, nitrate, and ammonium, respectively. These values represent 47%, 40%, 3%, and 10%, respectively, of the measured submicron aerosol mass. Based on Q‐AMS spectra, OM was apportioned to hydrocarbon‐like organic aerosol (HOA, likely representing primary organic aerosol) and two types of oxidized organic aerosol (OOA‐1 and OOA‐2), which constituted on average 6%, 58%, and 36%, respectively, of the apportioned OM. OOA‐1 probably represents aged, regional secondary organic aerosol (SOA), while OOA‐2 likely reflects less aged SOA. Organic aerosol characteristics associated with the events are compared to the campaign averages. Particularly in one event, the contribution of OOA‐2 to overall OM levels was enhanced, indicating the likelihood of less aged SOA formation. Statistical analyses investigate the relationships between HOA, OOA‐1, OOA‐2, other aerosol components, gas‐phase species, and meteorological data during the campaign and individual events. No single variable clearly controls the occurrence of a particle growth event.

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Section: Measurementsmentioning

confidence: 99%

Characterization of aerosol associated with enhanced small particle number concentrations in a suburban forested environment

Ziemba¹,

Griffin²,

Cottrell³

et al. 2010

J. Geophys. Res.

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“…In this work, the ACM was coupled to a PTRToF-MS (model PTR-TOF 8000; Ionicon Analytik GmbH, Innsbruck, Austria). In brief, ambient air was sampled through an aerodynamic lens (Liu et al, 1995a, b) with a flow rate of 80 mL min −1 . Within the aerodynamic lens the gas and particle phase of an aerosol were separated, and the particles were collimated into a narrow beam.…”

Section: Acm-ptr-tof-msmentioning

confidence: 99%

“…Due to the particle humidification step these techniques may bias collection efficiency (CE) towards water-soluble compounds. The aerosol collection module (ACM) (Hohaus et al, 2010) collects aerosols by passing them through an aerodynamic lens for particle collimation (Liu et al, 1995a, b) and further through a vacuum system (comparable in design to the AMS), and finally impacting the particle phase on a cooled sampling surface. Although the ACM has a low time resolution (3-4 h), its design makes it applicable for the investigation of compound-specific thermodynamic properties, such as partitioning coefficient and volatility (Hohaus et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Comparison of three aerosol chemical characterization techniques utilizing PTR-ToF-MS: a study on freshly formed and aged biogenic SOA

Gkatzelis¹,

Tillmann²,

Hohaus³

et al. 2018

Atmos. Meas. Tech.

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Abstract. An intercomparison of different aerosol chemical characterization techniques has been performed as part of a chamber study of biogenic secondary organic aerosol (BSOA) formation and aging at the atmosphere simulation chamber SAPHIR (Simulation of Atmospheric PHotochemistry In a large Reaction chamber). Three different aerosol sampling techniques -the aerosol collection module (ACM), the chemical analysis of aerosol online (CHARON) and the collection thermal-desorption unit (TD) were connected to proton transfer reaction time-of-flight mass spectrometers (PTR-ToF-MSs) to provide chemical characterization of the SOA. The techniques were compared among each other and to results from an aerosol mass spectrometer (AMS) and a scanning mobility particle sizer (SMPS). The experiments investigated SOA formation from the ozonolysis of β-pinene, limonene, a β-pinene-limonene mix and real plant emissions from Pinus sylvestris L. (Scots pine). The SOA was subsequently aged by photo-oxidation, except for limonene SOA, which was aged by NO 3 oxidation. Despite significant differences in the aerosol collection and desorption methods of the PTR-based techniques, the determined chemical composition, i.e. the same major contributing signals, was found by all instruments for the different chemical systems studied. These signals could be attributed to known products expected from the oxidation of the examined monoterpenes. The sampling and desorption method of ACM and TD provided additional information on the volatility of individual compounds and showed relatively good agreement.Averaged over all experiments, the total aerosol mass recovery compared to an SMPS varied within 80 ± 10, 51 ± 5 and 27 ± 3 % for CHARON, ACM and TD, respectively. Comparison to the oxygen-to-carbon ratios (O : C) obtained by AMS showed that all PTR-based techniques observed lower O : C ratios, indicating a loss of molecular oxygen either during aerosol sampling or detection. The differences in total mass recovery and O : C between the three instruments resulted predominantly from differences in the field strength (E/N) in the drift tube reaction ionization chambers of the PTR-ToF-MS instruments and from dissimilarities in the collection/desorption of aerosols. Laboratory case studies showed that PTR-ToF-MS E/N conditions influenced fragmentation which resulted in water and further neutral fragment losses of the detected molecules. Since ACM and TD were operated in higher E/N than CHARON, this resulted in higher fragmentation, thus affecting primarily the detected oxygen and carbon content and therefore also the mass recovery. Overall, these techniques have been shown to provide

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“…The transmission efficiency for aerodynamic lens systems is generally said to be 100% for the range of sizes for which it was designed [14]. There will be an upper mass limit for plenum transmission just as there is for transmission through an aerodynamic lens system [14] that is based on the stopping distance of the particles [8,15]. For a 1-m diameter particle traveling at 500 m/s through a 2 Torr gas, the stopping distance is ϳ13 cm.…”

Section: Resultsmentioning

confidence: 99%

“…The particle transmission efficiency through the plenum chamber should be roughly as good as the transmission efficiency through an aerodynamic lens system given the similar flow patterns (see Figure 1b and reference [13] for a comparison). The transmission efficiency for aerodynamic lens systems is generally said to be 100% for the range of sizes for which it was designed [14]. There will be an upper mass limit for plenum transmission just as there is for transmission through an aerodynamic lens system [14] that is based on the stopping distance of the particles [8,15].…”

Section: Resultsmentioning

confidence: 99%

Controlling the expansion into vacuum—the enabling technology for trapping atmosphere-sampled particulate ions

Koizumi¹,

Wang

Whitten³

et al. 2010

J. Am. Soc. Mass Spectrom.

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A new inlet has been designed to control the kinetic energy distributions of ions into a large-radius, frequency-adjusted, linear quadrupole ion trap. The work presented here demonstrates trapping singly-charged, intact proteins in the 10 to 200 kDa range injected from the atmosphere. The trapped ions were held while collisions with a buffer gas removed the remaining amounts of expansion-induced kinetic energy. The ions were then ejected from the trap on-demand into an awaiting detector. There is no low mass limit for ion injection and trapping. The upper limit presented in this study was defined by the limit of the conversion dynode-based detector at ϳ1.5 MDa. Trapping larger masses should be achievable. The transmission and capture efficiency across the entire mass range should be very high because the entire flow from the inlet empties directly into the trap. The kinetic energy distribution of massive ions is the primary reason for the working range limitation of mass spectrometers. Trapping ions with collisional cooling before mass analysis permits the motion of the ions to be completely defined by the applied fields. For this reason, this new inlet and trapping system represents a large step toward sensitive, high-resolution mass spectrometry into the megadalton range and beyond. (J Am Soc Mass Spectrom 2010, 21, 242-248) © 2010 American Society for Mass Spectrometry A rguably, the greatest advances in mass spectrometry of large molecules came with the introduction and development of electrospray ionization (ESI) [1] and matrix-assisted laser desorption ionization (MALDI) [2]. The creation of massive ions in vacuum was the start of a revolution in biological analysis using mass spectrometry. Unfortunately, the molecular weight range of mass specific biological species, such as proteins, RNA, DNA, and even viruses was much larger than the mass range of the mass spectrometer from which useful information could be obtained. Yet, the information was so valuable that a multitude of techniques and an entire industry was developed over the past 20-plus years so that these biological species could be analyzed using mass spectrometry. The essential thrust of the advances (beyond ionization) that have permitted the use of mass spectrometry for biological analysis has been in areas of sample preparation and analysis techniques, which allow analytes that are larger than the range of the mass spectrometer to be characterized with it anyway.The thrust of our efforts has been to increase the range of mass spectrometers where they achieve good resolution, mass accuracy, and sensitivity. Our analysis suggested that the overarching reason for the limitation of mass spectrometers in general was the expansioninduced kinetic energy distribution of the ions as they are injected in the mass spectrometer. The average and spread of the kinetic energy distribution of the ions expanding into vacuum monotonically increases with increasing mass. It is not difficult to compensate for the average increase for a particular type of ion; ho...

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Generating Particle Beams of Controlled Dimensions and Divergence: I. Theory of Particle Motion in Aerodynamic Lenses and Nozzle Expansions

Cited by 504 publications

References 21 publications

Characterization of aerosol associated with enhanced small particle number concentrations in a suburban forested environment

Characterization of aerosol associated with enhanced small particle number concentrations in a suburban forested environment

Comparison of three aerosol chemical characterization techniques utilizing PTR-ToF-MS: a study on freshly formed and aged biogenic SOA

Controlling the expansion into vacuum—the enabling technology for trapping atmosphere-sampled particulate ions

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