scholarly journals Applications and limitations of constrained high-resolution peak fitting on low resolving power mass spectra from the ToF-ACSM

2016 ◽  
Author(s):  
Hilkka Timonen ◽  
Mike Cubison ◽  
Minna Aurela ◽  
David Brus ◽  
Heikki Lihavainen ◽  
...  
Keyword(s):  
High Resolution ◽  
Mass Spectra ◽  
Resolving Power ◽  
Sensitivity Analyses ◽  
Metal Species ◽  
Aerosol Mass ◽  
Aerosol Mass Spectrometry ◽  
Peak Fitting ◽  
Mass Resolving Power ◽  
Low Mass

Abstract. The applicability, methods and limitations of constrained peak-fitting on mass spectra of low mass resolving power (m/dm50 ~ 500) recorded with a time-of-flight aerosol chemical speciation monitor (ToF-ACSM) are explored. Calibration measurements as well as ambient data are used to exemplify the methods that should be applied to maximise data quality and assess confidence in peak-fitting results. Sensitivity analyses and basic peak fit metrics such as normalised ion separation are employed to demonstrate which peak-fitting analyses commonly performed in high-resolution aerosol mass spectrometry are appropriate to perform on spectra of this resolving power. Information on aerosol sulphate, nitrate, sodium chloride, methanesulphonic acid as well as semi-volatile metal species retrieved from these methods is evaluated. The constants in a commonly used formula for the estimation of the mass concentration of hydrocarbon-like organic aerosol may be refined based on peak-fitting results. Finally, application of a recently-published parameterisation for the estimation of carbon oxidation state to ToF-ACSM spectra is validated for a range of organic standards and its use demonstrated for ambient urban data.

scholarly journals Applications and limitations of constrained high-resolution peak fitting on low resolving power mass spectra from the ToF-ACSM

2016 ◽  
Vol 9 (7) ◽  
pp. 3263-3281 ◽  
Author(s):  
Hilkka Timonen ◽  
Mike Cubison ◽  
Minna Aurela ◽  
David Brus ◽  
Heikki Lihavainen ◽  
...  
Keyword(s):  
High Resolution ◽  
Mass Spectra ◽  
Methanesulfonic Acid ◽  
Resolving Power ◽  
Sensitivity Analyses ◽  
Metal Species ◽  
Aerosol Mass ◽  
Peak Fitting ◽  
Mass Resolving Power ◽  
Low Mass

Abstract. The applicability, methods and limitations of constrained peak fitting on mass spectra of low mass resolving power (m∕Δm50 ∼ 500) recorded with a time-of-flight aerosol chemical speciation monitor (ToF-ACSM) are explored. Calibration measurements as well as ambient data are used to exemplify the methods that should be applied to maximise data quality and assess confidence in peak-fitting results. Sensitivity analyses and basic peak fit metrics such as normalised ion separation are employed to demonstrate which peak-fitting analyses commonly performed in high-resolution aerosol mass spectrometry are appropriate to perform on spectra of this resolving power. Information on aerosol sulfate, nitrate, sodium chloride, methanesulfonic acid as well as semi-volatile metal species retrieved from these methods is evaluated. The constants in a commonly used formula for the estimation of the mass concentration of hydrocarbon-like organic aerosol may be refined based on peak-fitting results. Finally, application of a recently published parameterisation for the estimation of carbon oxidation state to ToF-ACSM spectra is validated for a range of organic standards and its use demonstrated for ambient urban data.

On the Field Evaporation Behavior of a Model Ni-Al-Cr Superalloy Studied by Picosecond Pulsed-Laser Atom-Probe Tomography

2008 ◽  
Vol 14 (6) ◽  
pp. 571-580 ◽  
Author(s):  
Yang Zhou ◽  
Christopher Booth-Morrison ◽  
David N. Seidman
Keyword(s):  
Atom Probe Tomography ◽  
Mass Spectra ◽  
Pulsed Laser ◽  
Picosecond Laser ◽  
Atom Probe ◽  
Resolving Power ◽  
Noise Levels ◽  
Thermally Activated ◽  
Mass Resolving Power

AbstractThe effects of varying the pulse energy of a picosecond laser used in the pulsed-laser atom-probe (PLAP) tomography of an as-quenched Ni-6.5 Al-9.5 Cr at.% alloy are assessed based on the quality of the mass spectra and the compositional accuracy of the technique. Compared to pulsed-voltage atom-probe tomography, PLAP tomography improves mass resolving power, decreases noise levels, and improves compositional accuracy. Experimental evidence suggests that Ni2+, Al2+, and Cr2+ ions are formed primarily by a thermally activated evaporation process, and not by post-ionization of the ions in the 1+ charge state. An analysis of the detected noise levels reveals that for properly chosen instrument parameters, there is no significant steady-state heating of the Ni-6.5 Al-9.5 Cr at.% tips during PLAP tomography.

Identification of amines in wintertime ambient particulate material using high resolution aerosol mass spectrometry

2018 ◽  
Vol 180 ◽  
pp. 173-183 ◽  
Author(s):  
Courtney L.H. Bottenus ◽  
Paola Massoli ◽  
Donna Sueper ◽  
Manjula R. Canagaratna ◽  
Graham VanderSchelden ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Particulate Material ◽  
Aerosol Mass ◽  
Aerosol Mass Spectrometry

scholarly journals Mexico City aerosol analysis during MILAGRO using high resolution aerosol mass spectrometry at the urban supersite (T0) – Part 1: Fine particle composition and organic source apportionment

2009 ◽  
Vol 9 (2) ◽  
pp. 8377-8427 ◽  
Author(s):  
A. C. Aiken ◽  
D. Salcedo ◽  
M. J. Cubison ◽  
J. A. Huffman ◽  
P. F. DeCarlo ◽  
...  
Keyword(s):  
High Resolution ◽  
Mexico City ◽  
Biomass Burning ◽  
Emissions Inventory ◽  
Secondary Sources ◽  
Diurnal Cycles ◽  
Aerosol Mass ◽  
Aerosol Mass Spectrometry ◽  
Order Of Magnitude ◽  
Primary Emissions

Abstract. Submicron aerosol was analyzed during the MILAGRO field campaign in March 2006 at the T0 urban supersite in Mexico City with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and complementary instrumentation. Mass concentrations, diurnal cycles, and size distributions of inorganic and organic species are similar to results from the CENICA supersite in April 2003 with organic aerosol (OA) comprising about half of the fine PM mass. Positive Matrix Factorization (PMF) analysis of the high resolution OA spectra identified three major components: chemically-reduced urban primary emissions (hydrocarbon-like OA, HOA), oxygenated OA (OOA, mostly secondary OA or SOA), and biomass burning OA (BBOA) that correlates with levoglucosan and acetonitrile. BBOA includes several very large plumes from regional fires and likely also some refuse burning. A fourth OA component is a small local nitrogen-containing reduced OA component (LOA) which accounts for 9% of the OA mass but one third of the organic nitrogen, likely as amines. OOA accounts for almost half of the OA on average, consistent with previous observations. OA apportionment results from PMF-AMS are compared to the PM2.5 chemical mass balance of organic molecular markers (CMB-OMM, from GC/MS analysis of filters). Results from both methods are overall consistent. Both assign the major components of OA to primary urban, biomass burning/woodsmoke, and secondary sources at similar magnitudes. The 2006 Mexico City emissions inventory underestimates the urban primary PM2.5 emissions by a factor of ~4, and it is ~16 times lower than afternoon concentrations when secondary species are included. Additionally, the forest fire contribution is underestimated by at least an order-of-magnitude in the inventory.

A high resolution multi-turn TOF mass analyzer

2019 ◽  
Vol 34 (36) ◽  
pp. 1942005 ◽  
Author(s):  
Vyacheslav Shchepunov ◽  
Michael Rignall ◽  
Roger Giles ◽  
Ryo Fujita ◽  
Hiroaki Waki ◽  
...  
Keyword(s):  
High Resolution ◽  
Mirror Symmetry ◽  
Rotational Symmetry ◽  
Optical Design ◽  
Resolving Power ◽  
Mass Analyzer ◽  
Rotationally Symmetric ◽  
Mass Resolving Power ◽  
Operational Modes ◽  
Drift Direction

An ion optical design of a high resolution multi-turn time-of-flight mass analyzer (MT-TOF MA) is presented. The analyzer has rotationally symmetric main electrodes with additional mirror symmetry about a mid-plane orthogonal to the axis of symmetry. Rotational symmetry allows a higher density of turns in the azimuthal (drift) direction compared to MT-TOF MAs that are linearly extended in the drift direction. Mirror symmetry about a mid-plane helps to achieve a high spatial isochronicity of the ions’ motion. The analyzer comprises a pair of polar-toroidal sectors S1 and S3, a pair of polar (trans-axial) lenses, and a pair of conical lenses for longitudinal and lateral focusing. A toroidal sector S2 located at the mid-plane of the analyzer has a set of embedded drift focusing segments providing focusing and spatial isochronicity in the drift direction. The ions’ drift in the azimuthal direction can be reversed by using dedicated reversing deflectors. This gives the possibility of several operational modes with different numbers of turns and passes in the drift direction. According to numerical simulations, the mass resolving power of the analyzer ranges from [Formula: see text]40 k (fwhm) at small (typically below ten) numbers of turns to [Formula: see text]450 k (fwhm) at 96 turns.

Aerosol Chemical Composition in Cloud Events by High Resolution Time-of-Flight Aerosol Mass Spectrometry

2013 ◽  
Vol 47 (6) ◽  
pp. 2645-2653 ◽  
Author(s):  
Liqing Hao ◽  
Sami Romakkaniemi ◽  
Aki Kortelainen ◽  
Antti Jaatinen ◽  
Harri Portin ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Chemical Composition ◽  
High Resolution ◽  
Time Of Flight ◽  
Resolution Time ◽  
Aerosol Mass ◽  
Aerosol Mass Spectrometry ◽  
Aerosol Chemical Composition

scholarly journals A new method to discriminate secondary organic aerosols from different sources using high-resolution aerosol mass spectra

2012 ◽  
Vol 12 (4) ◽  
pp. 2189-2203 ◽  
Author(s):  
M. F. Heringa ◽  
P. F. DeCarlo ◽  
R. Chirico ◽  
T. Tritscher ◽  
M. Clairotte ◽  
...  
Keyword(s):  
High Resolution ◽  
Mass Spectra ◽  
Principal Component ◽  
Particle Growth ◽  
Organic Aerosol ◽  
Diesel Emissions ◽  
Anthropogenic Sources ◽  
Inlet System ◽  
Alpha Pinene ◽  
Aerosol Mass

Abstract. Organic aerosol (OA) represents a significant and often major fraction of the non-refractory PM1 (particulate matter with an aerodynamic diameter da < 1 μm) mass. Secondary organic aerosol (SOA) is an important contributor to the OA and can be formed from biogenic and anthropogenic precursors. Here we present results from the characterization of SOA produced from the emissions of three different anthropogenic sources. SOA from a log wood burner, a Euro 2 diesel car and a two-stroke Euro 2 scooter were characterized with an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS) and compared to SOA from α-pinene. The emissions were sampled from the chimney/tailpipe by a heated inlet system and filtered before injection into a smog chamber. The gas phase emissions were irradiated by xenon arc lamps to initiate photo-chemistry which led to nucleation and subsequent particle growth by SOA production. Duplicate experiments were performed for each SOA type, with the averaged organic mass spectra showing Pearson's r values >0.94 for the correlations between the four different SOA types after five hours of aging. High-resolution mass spectra (HR-MS) showed that the dominant peaks in the MS, m/z 43 and 44, are dominated by the oxygenated ions C2H3O+ and CO2+, respectively, similarly to the relatively fresh semi-volatile oxygenated OA (SV-OOA) observed in the ambient aerosol. The atomic O:C ratios were found to be in the range of 0.25–0.55 with no major increase during the first five hours of aging. On average, the diesel SOA showed the lowest O:C ratio followed by SOA from wood burning, α-pinene and the scooter emissions. Grouping the fragment ions revealed that the SOA source with the highest O:C ratio had the largest fraction of small ions. The HR data of the four sources could be clustered and separated using principal component analysis (PCA). The model showed a significant separation of the four SOA types and clustering of the duplicate experiments on the first two principal components (PCs), which explained 79% of the total variance. Projection of ambient SV-OOA spectra resolved by positive matrix factorization (PMF) showed that this approach could be useful to identify large contributions of the tested SOA sources to SV-OOA. The first results from this study indicate that the SV-OOA in Barcelona is strongly influenced by diesel emissions in winter while in summer at SIRTA at the southwestern edge of Paris SV-OOA is more similar to alpha-pinene SOA. However, contributions to the ambient SV-OOA from SOA sources that are not covered by the model can cause major interference and therefore future expansions of the PCA model with additional SOA sources is recommended.

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