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Author : Berk Oktem
Publisher :
ISBN 13 :
Total Pages : 278 pages
Book Rating : 4.:/5 (55 download)
Download or read book Organic Aerosol Characterization by Mass Spectrometry written by Berk Oktem and published by . This book was released on 2004 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Yuqian Gao
Publisher :
ISBN 13 : 9781124611839
Total Pages : pages
Book Rating : 4.6/5 (118 download)
Download or read book Molecular Characterization of Organic Aerosol by Mass Spectrometry written by Yuqian Gao and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic aerosol is a major constituent of atmospheric fine particles, especially over continental regions. These particles adversely affect human health and global climate. A significant fraction of organic aerosol is considered to be from the oxidation products of ozone and volatile organic compounds, which are called secondary organic aerosol (SOA). To study the formation mechanisms of secondary organic aerosol, it is important to characterize their molecular composition. The composition of secondary organic aerosol is very complex including thousands of species with molecular weight up to over a thousand Dalton. Methods utilized for the identification of these oxidation products involve advanced mass spectrometry techniques. In this dissertation, three mass spectrometry techniques were developed to study the molecular composition of organic aerosol. Firstly, online nano-aerosol sample deposition methods for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry was developed to incorporate matrix particles directly with analyte particles onto a conventional MALDI plate. Secondly, a microsampling and analysis technique was developed in order to collect microgram samples and analyze them with high performance mass spectrometry. With this technique, the molecular composition of particle phase SOA at a low mass loading can be elucidated, which provides information about SOA formation at the early stages. A species with the (neutral molecule) formula C 17 H 26 O 8 (MW 358) increased substantially in intensity relative to other products as the mass loading decreased. Tandem mass spectrometry (MS n) of this species showed it to be a dimer of C 9 H 14 O 4 and C 8 H 12 O 4, most likely pinic acid and terpenylic acid, respectively. This species is likely to be critical at the early stages of SOA formation. Thirdly, ambient secondary electrospray ionization (ESI) source was designed to characterize the molecular composition of both gas and particle phases SOA online. This ion source was demonstrated to be applicable to a wide range of mass spectrometers having an ambient inlet. This technique provides a tool to acquire detailed information about possible SOA nucleation agents. A species with the (neutral molecule) formula C 20 H 36 O 6 (MW 372) was found in the gas-phase products of SOA, which could be critical for the new particle formation of SOA. Tandem mass spectrometry (MS n) of this species showed it to be a dimer of an organic hydroperoxide C 10 H 18 O 3, which is likely formed via OH-initiated oxidation pathway.
Author : Katherine J. Heaton
Publisher :
ISBN 13 : 9781124086231
Total Pages : pages
Book Rating : 4.0/5 (862 download)
Download or read book Characterization of Biogenic Secondary Organic Aerosol Using Mass Spectrometry written by Katherine J. Heaton and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Secondary Organic Aerosol (SOA) forms in the atmosphere from the oxidation of biogenic emissions. Even though SOA has been linked to health and climate effects, the chemical mechanism of SOA formation is not well understood. Through the use of mass spectrometry, this work characterizes SOA during the early stages of growth from the reaction of ozone with monoterpenes, a major biogenic emission. In this thesis, three types of studies are described for analyzing SOA formation: (1) the molecular composition of SOA is studied using the photoionization aerosol mass spectrometer, (2) the atomic composition is studied with the nanometer aerosol mass spectrometer and (3) high resolution mass spectrometry is used to help reconcile atomic and molecular composition data. The monoterpene ozonolysis reactions were performed in a flow tube reactor, where the reaction period could vary from 3s to 22s. The Photoionization Aerosol Mass Spectrometer (PIAMS) detected the formation of oligomers within seconds of the onset of the reaction. Ions that were detected were mapped to dimers that could form via the stabilized Criegee intermediate channel or the hydroperoxy channel. The Nanometer Aerosol Mass Spectrometer (NAMS) analyzed the elemental composition of the SOA which showed the formation of highly polar compounds during the early stages of SOA growth. NAMS also analyzed the changes in the composition of SOA when it formed in the presence of atmospheric species (water vapor, nitric acid vapor and sodium chloride seed particles). The data collected indicated that there is not as much change for endocyclic compounds as there is for exocyclic compounds. Finally, a new off-line analysis technique was created to micro-extract SOA deposited on a plate from the flow tube reactor. The samples were analyzed with the Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FTICR-MS). The FTICR-MS was used to collect molecular and elemental data simultaneously. The FTICR-MS produced accurate mass data that could be used to calculate molecular formulas. This provided a direct comparison of the data acquired with PIAMS and NAMS.
Author : Quentin Gerald James Malloy
Publisher :
ISBN 13 :
Total Pages : 414 pages
Book Rating : 4.3/5 (121 download)
Download or read book Chemical and Physical Characterization of Secondary Organic Aerosol Formation from Select Agricultural Emissions written by Quentin Gerald James Malloy and published by . This book was released on 2009 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 64 pages
Book Rating : 4.:/5 (933 download)
Download or read book Characterization of Secondary Organic Aerosol Precursors Using Two-Dimensional Gas Chromatography with Time of Flight Mass Spectrometry (GC×GC/TOFMS) written by and published by . This book was released on 2013 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: The oxidation of volatile organic compounds (VOCs) plays a role in both regional and global air quality through the formation of secondary organic aerosols (SOA). More than 1000TgC/yr of non-methane VOCs are emitted from biogenic sources (significantly greater than from anthropogenic sources). Despite this magnitude and potential importance for air quality, the body of knowledge around the identities, quantities and oxidation processes of these compounds is still incomplete (e.g., Goldstein & Galbally, 2007; Robinson et al., 2009). Two-dimensional gas chromatography paired with time-of-flight mass spectrometry (GC×GC/TOFMS) is a powerful analytical technique which is explored here for its role in better characterizing biogenic VOCs (BVOCs) and thus SOA precursors.
Author : Felipe Daniel Lopez-Hilfiker
Publisher :
ISBN 13 :
Total Pages : 178 pages
Book Rating : 4.:/5 (932 download)
Download or read book A Molecular Characterization of Biogenic Secondary Organic Aerosol by High-resolution Time-of-flight Mass Spectrometry written by Felipe Daniel Lopez-Hilfiker and published by . This book was released on 2015 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: The guiding question to this research is: To what extent and by what mechanisms do biogenic volatile organic compounds contribute to atmospheric aerosol mass? To address this question we need to understand the chemistry that produces condensable vapors which when in the presence of particles may partition onto the aerosol surface depending on their chemical and physical properties. I developed an insitu gas and aerosol sampling system, the FIGAERO (Filter Inlet for Gases and AEROsol) to speciate gas and particle phase organics derived from photochemical reactions with biogenic volatile organic compounds under both field and laboratory conditions. By coupling the FIGAERO to a High-Resolution Time-of-Flight Chemical Ionization Mass Spectrometer (HR-TOF-CIMS) I am able to elucidate chemical pathways by identifying elemental compositions and in some cases functional groups present in the detected molecular ions. The coupling of the FIGAERO to the HR-TOF-CIMS also allows the estimation of effective vapor pressures of the aerosol components and this information can be used to improve vapor pressure models and test associated partitioning theories and parameterizations. The approach also provides hundreds of speciated chemical tracers that can be correlated with traditional environmental and chemical measurements (e.g AMS, NOx, SO2, SMPS, VOC) to help derive sources and sinks and to constrain the mechanisms responsible for the formation and growth of organic aerosol. Measurements obtained across a wide range of conditions and locations allowing connections and contrasts between different chemical systems, providing insights into generally controlling factors of secondary organic aerosol (SOA) and its properties.
Author : Yun Zhang
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (139 download)
Download or read book Chemical Characterization of Atmospheric Organic Aerosol Using Ultrahigh Resolution Mass Spectrometry and Molecular Evidence for the Association with Reactive Oxygen Species Formation written by Yun Zhang and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development and Characterization of Two Versions of a New Single Particle Mass Spectrometer for Organic Aerosol Analysis that Incorporate a 3D Ion Trap written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosol particles are ubiquitous throughout the atmosphere and play an important role in human health, climate, and the chemistry of the atmosphere. A significant mass fraction of these particles is composed of organic species, which remain poorly characterized due to the number and diversity of species present. This thesis describes the development and characterization of two versions of a new single particle mass spectrometer with a 3D ion trap for organic aerosol studies. Version I combines CO2 laser desorption and electron impact ionization in an ion trap. Mass spectra obtained for four species are comparable to NIST EI spectra. Tandem mass spectrometry studies are also demonstrated. The effects of vaporization energy, ionization delay time, and electron pulse width on the mass spectra and fragmentation patterns are examined. The detection limit of the instrument is found to be ~1x108 molecules (350 nm diameter particle) for 2,4-dihydroxybenzoic acid. Version II integrates CO2 laser desorption and tunable VUV ionization in an ion trap and was used for a detailed study of oleyl alcohol, oleic acid and mixtures thereof. Both the degree of fragmentation in the mass spectra and the translational energy of the vaporized molecules are found to vary as a function of desorption energy in the pure particles and as a function of composition in the mixed particles. These changes can be described by the energy absorbed per particle during desorption. We show that these effects hinder the quantitative response of the instrument and have important implications for other two step laser desorption/ionization systems. The final part of this thesis presents preliminary results from atmospherically relevant particles. Mass spectra of cigarette sidestream smoke, fulvic acid, meat cooking, and ammonium bisulfate aerosols are collected using both versions of the instrument. The two step desorption/ionization process only worked for two types of aerosols, while CO2 only mass spectra w.
Author : Kai Wang
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (113 download)
Download or read book Chemical Characterization of Organic Aerosol from Chinese Cities Using High Resolution Mass Spectrometry written by Kai Wang and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Peter H. McMurry
Publisher : Cambridge University Press
ISBN 13 : 9780521842877
Total Pages : 652 pages
Book Rating : 4.8/5 (428 download)
Download or read book Particulate Matter Science for Policy Makers written by Peter H. McMurry and published by Cambridge University Press. This book was released on 2004-11-29 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt: Particulate Matter Science for Policy Makers: A NARSTO Assessment was commissioned by NARSTO, a cooperative public-private sector organization of Canada, Mexico and the United States. It is a concise and comprehensive discussion of the current understanding by atmospheric scientists of airborne particulate matter (PM). Its goal is to provide policy makers who implement air-quality standards with this relevant and needed scientific information. The primary audience for this volume will be regulators, scientists, and members of industry, all of whom have a stake in effective PM management. It will also inform exposure and health scientists, who investigate causal hypotheses of health impacts, characterize exposure, and conduct epidemiological and toxicological studies.
Author : Rachel Elizabeth Sellon
Publisher :
ISBN 13 :
Total Pages : 274 pages
Book Rating : 4.:/5 (839 download)
Download or read book Characterization of the Molecular Composition of Secondary Organic Aerosols Using High Resolution Mass Spectrometry written by Rachel Elizabeth Sellon and published by . This book was released on 2012 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atmospheric aerosols can affect visibility and the Earth's climate by scattering and absorbing light and they also can have adverse effects on human health. The organic portion of atmospheric aerosols is very complex and is a major fraction of fine particulate matter. High molecular weight (high-MW)/oligomeric organic compounds can make up a large part of this organic fraction and the composition, sources, and formation mechanisms for these compounds are not well understood. This knowledge and understanding is necessary to decrease the uncertainty in the climate affects of aerosols and to improve climate models. This dissertation investigates the composition and formation mechanisms for the high-MW/oligomeric fraction of secondary organic aerosols (SOA) collected in Bakersfield, CA and presents a comparative analysis of chamber and ambient SOA, from both Los Angeles (LA) and Bakersfield, to investigate sources at both locations. A novel sampling technique, nanospray-Desorption Electrospray Ionization (nano-DESI), was used with high resolution mass spectrometry (HR-MS) to determine the molecular formulas of the high molecular weight (HMW)/oligomeric fraction of SOA. Nano-DESI involves direct desorption from the sample surface and was used to limit reactions that can take place with extraction and storage in solvent. The samples were collected in Bakersfield and LA during CalNex 2010. Both Bakersfield and LA are out of compliance with EPA standards of ozone and particulate matter and provide opportunities to examine air masses affected by both anthropogenic and biogenic sources. This dissertation has provided the first evidence of observable changes in the composition of high-MW/oligomeric compounds throughout the day. Using positive mode nano-DESI, afternoon increases in the number of compounds that contain carbon, hydrogen and oxygen (CHO) were observed consistent with photochemistry/ozonolysis as a major source for these compounds. Compounds containing reduced nitrogen groups were dominant at night and had precursors consistent with imine formation products from the reaction of carbonyls and ammonia. In the negative mode, organonitrates (CHON) and nitroxy organosulfates (CHONS) had larger numbers of compounds in the night/morning samples consistent with nitrate radical formation reactions. A subset of the CHONS compounds and compounds containing sulfur (CHOS) had the same composition as known biogenic organosulfates and nitroxy organosulfates indicating contributions from both biogenic and anthropogenic sources to the SOA. This dissertation also provides the first analysis of the high-MW/oligomeric fraction in size resolved samples; the majority of the compounds were found in aerosol diameters between 0.18-1.0 micrometers and the CHON were bimodal with size. Finally, this dissertation presents the first comparative analysis of the overlap in the composition of this fraction of SOA between ambient and chamber samples. Samples collected in Pasadena, LA and Bakersfield were compared with samples collected in a smog chamber using diesel and isoprene sources. The results indicate that diesel had the highest overlap at both sites, Bakersfield samples were more oxidized, and LA showed evidence of a SOA plume arriving from downtown LA. The addition of ammonia to the diesel chamber experiment was necessary to form many of the 2N compounds found in Bakersfield. These results increase our understanding of the types of compounds found in urban environments and give evidence for the timescales of formation reactions in an ambient environment. They show that the majority of the high-MW oligomeric compounds are found in submicron size particles and that the composition of this fraction of SOA varies with aerosol size. Results from the chamber comparisons show that both diesel and isoprene are important sources for these compounds and also that there other sources are present. Future work that combines this type of analysis, in other ambient environments, with studies of the optical properties of aerosols could be used to help improve climate models and to start to close the gap in our understanding of the climate effects of atmospheric aerosols.
Author : Fred Warren McLafferty (Chemiker, USA)
Publisher :
ISBN 13 : 9780805370485
Total Pages : 278 pages
Book Rating : 4.3/5 (74 download)
Download or read book Interpretation of Mass Spectra written by Fred Warren McLafferty (Chemiker, USA) and published by . This book was released on 1973 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Farhat Yasmeen
Publisher :
ISBN 13 :
Total Pages : 103 pages
Book Rating : 4.:/5 (866 download)
Download or read book Characterization of Secondary Organic Aerosols in the Atmosphere by Using Mass Spectrometric Approaches written by Farhat Yasmeen and published by . This book was released on 2010 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt: Secondary organic aerosol (SOA) accounts for a significant fraction of ambient tropospheric aerosol. The chemical composition of SOA is highly uncertain as it depends on different ongoing chemical and physical processes of biogenic volatile organic compounds (BVOC) and anthropogenic volatile organic compounds in the atmosphere. The research performed within the frame of this doctoral thesis is focused on the characterization of SOA produced from BVOC under a variety of atmospheric reactions resorting to mass spectrometric approaches. In a first study, the aqueous-phase oligomer formation of a major atmospheric photooxidation product, i.e., methylglyoxal, has been investigated to explore an additional pathway producing SOA through cloud processes during night-time. A second study deals with the chemical characterization (sulfate and organic matter) of marine aerosols. methanesulfonic acid was the dominating organic compound in in the fine size fraction of aerosol. A third study concerns the structural characterization of a dimeric [alpha]- and [beta]-pinene SOA product. It is proposed that diaterpenylic acid is a key monomeric unit for dimers of the ester type. A fourth study deals with the chemical characterization by fragmentation of major terpenoic acids in ambient fine aerosols from a rural site. Emphasis is given to the mass spectrometric differentiation of isobaric terpenoic acids that occur in fine forest aerosol. This thesis presents results on aerosol characterization from a wide range of parent organic compounds under a variety of atmospheric conditions.
Download or read book MOLECULAR CHARACTERIZATION OF FREE TROPOSPHERIC ORGANIC AEROSOL AND THE DEVELOPMENT OF COMPUTATIONAL TOOLS FOR MOLECULAR FORMULA ASSIGNMENT written by and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Organic aerosol affects human health and climate. These effects are largely determined by the composition of the organic aerosol, which is a complex mixture of species. Understanding the complexity of organic aerosol is critical to determining its effect on human health and climate. In this study, long range transported organic aerosol collected at the Pico Mountain Observatory was analyzed using ultrahigh resolution mass spectrometry. Organic aerosol transported in the free troposphere had an overall lower extent of oxidation than aerosol transported in the boundary layer. It was hypothesized that the lower oxidation was related to a more viscous phase state of the aerosol during transport. The results suggest that biomass burning organic aerosol injected into the free troposphere are more persistent than organic aerosol in the boundary layer. A sample was also analyzed using tandem FT-ICR MS/MS fragmentation, providing information about the functional group composition in the aerosol sample. This was done using a segmented scan approach, which revealed an unprecedented molecular complexity of unfragmented precursor ions. In addition to the expected CO2 and H2O neutral losses, neutral losses corresponding to carbonyl functional groups (C2H4O, CO) were observed. The abundance of carbonyl functional groups suggests a slower rate of aging in the atmosphere. Analysis of nitrogen and sulfur containing neutral losses highlighted a surprising abundance of reduced nitrogen and sulfur loss (NH3 and SH2). This further supports the hypothesis of slower aging in the free troposphere. Additional research was done to develop an R software package (MFAssignR) to perform molecular formula assignment with improved decision-making transparency, noise estimation, isotope identification, and mass recalibration. MFAssignR was found to assign the same molecular formula as other molecular formula assignment methods for the majority (97-99%) of mass peaks that were assigned a molecular formula by the compared methods. Additionally, MFAssignR was more effective at assigning molecular formulas to low intensity peaks relative to the other methods tested, leading to more overall molecular formula assignments. MFAssignR is available via GitHub and is the first open source package to contain a full pipeline of functions for data preparation and analysis for ultrahigh resolution mass spectrometry.
Author : Wiley A. Hall
Publisher :
ISBN 13 : 9781267214751
Total Pages : pages
Book Rating : 4.2/5 (147 download)
Download or read book Characterization of Oligomers in Secondary Organic Aerosol Using Advanced Mass Spectrometry Techniques written by Wiley A. Hall and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Biogenic secondary organic aerosol (SOA) forms from the reaction of gas phase organic molecules from biological sources with an atmospheric oxidant. Although biogenic SOA can comprise up to 80% of the particulate mass suspended in the atmosphere, the reactions that form SOA and the chemical identities of the compounds it contains are poorly understood, especially the oligomeric species that form the non-volatile core of SOA. In this dissertation, mass spectrometric techniques are used to characterize the oligomers found in SOA throughout their lifetime. Fresh aerosol was generated in a Tedlar bag and flow tube reactor (FTR) to determine: (1) the relevance of laboratory-generated oligomers to the atmosphere, and (2) the formation routes, and identity of the oligomers. Fresh SOA generated in the FTR was then reacted in a chamber designed to simulate photooxidation to (3) study the aging of SOA oligomers and determine if they are a source of highly oxidized atmospheric SOA. A scanning mobility particle sizer (SMPS) was found to accurately measure the concentration and size distribution of SOA. The SOA was then collected onto Teflon coated, glass fiber filters. Filter phase reactions were found to be minimal or non-existent. Various extraction solvents were tested, and acetonitrile was found to have high extraction efficiency without causing side reactions with the sample. Through the method of standard additions, the concentration of oligomeric species in the non-volatile core of the SOA collected and extracted was determined to be ~50% for laboratory SOA. SOA generated in the FTR was shown to have similar behavior as a class of organic aerosol found in the atmosphere. High resolution mass spectra revealed that oligomers undergo thermal degradation to volatile compounds when heated to high temperatures, so thermodenuders cannot be used to determine SOA volatility. High resolution tandem mass spectrometry (MSMS) was used to determine which compounds react to form oligomers and what their routes of formation are. By examining the product ions formed by dissociating oligomeric precursor ions, the monomers that are most likely to react were determined. Additionally, by searching precursor ions for the expected products of reported oligomerization reactions and examining their fragmentation spectra, several reported reactions were confirmed. These include the reactions of hydroperoxides, carbonyls and stabilized Criegee intermediates. Finally, an aerosol reaction chamber was constructed to test the theory that the oligomers found in SOA are sources of the highly oxidized class of organic aerosol found in the atmosphere after undergoing photo-oxidative aging. Freshly formed SOA was exposed to high levels of hydroxyl radical and then analyzed both online by the nanoaerosol mass (NAMS) spectrometer and off line by high resolution mass spectrometry. The average O:C and H:C ratios of the aged compounds were in the range reported for highly oxidized atmospheric SOA. Additionally, the extent of evaporation caused by the fragmentation of oligomers into smaller volatile species was not found to be significant enough to be a sink of atmospheric SOA, although the time scale of the experiment may not have been sufficient for evaporation to occur.
Author : Emily Anne Bruns
Publisher :
ISBN 13 : 9781267057884
Total Pages : 166 pages
Book Rating : 4.0/5 (578 download)
Download or read book Using Mass Spectrometry and Ftir to Characterize Atmospherically-relevant Particles Generated in Laboratory Systems written by Emily Anne Bruns and published by . This book was released on 2011 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atmospheric aerosols are known to have multifaceted effects on human health, visibility and climate. To understand these effects, characterization of aerosol properties is necessary. This dissertation focuses on several specific topics with the overall goal of improving our understanding of aerosols in the atmosphere. One area of importance is particulate organic nitrates, which are known to be ubiquitous in the atmosphere; however, there is a lack of proven analytical techniques for their measurement. The qualitative and quantitative response of a high resolution time of flight aerosol mass spectrometer to particulate organic nitrates was studied by analyzing secondary organic aerosol (SOA) from NO3 radical reactions with [Alpha]- and [Beta]-pinene, 3-carene, limonene, and isoprene. Extensive fragmentation of the organic nitrate products was observed in the mass spectra, which precluded molecular speciation. Another area of interest is the recent development of a number of ambient ionization techniques, which are promising for aerosol characterization. One such technique, atmospheric solids analysis probe mass spectrometry (ASAP-MS), was applied for the first time to the identification of organics in SOA, which was generated in the laboratory from the ozonolysis of & alpha;-pinene and isoprene, and from the NO3 oxidation of & alpha;-pinene. Also, ambient samples were collected from a forested and a suburban location. ASAP-MS data for the laboratory-generated samples showed peaks corresponding to well-known products of these reactions, and higher molecular weight oligomers were present in all samples. This is consistent with previously published studies of similar systems and shows that ASAP-MS should have wide applicability in both laboratory and field studies. Vapor pressures of low volatility compounds are important parameters in several atmospheric processes, including the formation of new particles and the partitioning of compounds between the gas-phase and particles. However, vapor pressures of low volatility compounds are challenging to measure and reported values vary significantly, illustrating the need for new approaches. ASAP-MS was applied for the first time to the measurement of vapor pressures and heats of sublimation. The measured heats of sublimation were in good agreement with published values. The vapor pressures were typically within a factor of three of published values made at similar temperatures. This study establishes that ASAP-MS is a promising new technique for vapor pressure and heat of sublimation measurements of low volatility compounds. To further understand new particle formation, laboratory and field measurements were made to identify gas-phase amines, which could play a role in new particle formation, from previously unknown sources using proton transfer reaction mass spectrometry. The work presented in this dissertation advances our understanding of aerosols and explores novel methods for their characterization.
Author : Sandra Louise Blair
Publisher :
ISBN 13 : 9781339820262
Total Pages : 228 pages
Book Rating : 4.8/5 (22 download)
Download or read book Composition and Photochemistry of Anthropogenic and Biogenic Organic Aerosols written by Sandra Louise Blair and published by . This book was released on 2016 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosols can substantially impact human health, atmospheric chemistry, and climate. The composition and photochemistry of a variety of anthropogenic and biogenic primary and secondary organic aerosols (POA and SOA) have yet to be fully characterized. The composition of organic aerosols is extremely complex - they contain a variety of highly oxidized, multifunctional, low vapor pressure organic compounds. The primary focus of this thesis is on the molecular characterization of organic aerosols that are not well understood or have not been studied before, such as primary emissions from electronic cigarettes, iron (III) mediated SOA, and photooxidized biodiesel and diesel fuel SOA. Another focus of this dissertation is the effect of direct photochemical aging on the composition of organic aerosol. Direct photolysis experiments were first applied to a system that is known to have a photolabile composition, alpha-pinene ozonolysis SOA, such that characterization of a photochemical effect would be possible to quantify. Photolysis of more complex SOA that have not been studied before, photooxidized biodiesel and diesel fuel SOA, were also investigated in this thesis. Advanced high resolution mass spectrometry techniques were used in the molecular characterization of organic aerosols, including nano-Desorption Electrospray Ionization Mass Spectrometry (nano-DESI) and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR). An additional suite of online instrumentation was used to measure gas-phase composition, particle-phase composition, particle size and concentration, and absorption properties: Proton Transfer Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS), Aerosol Mass Spectrometry (ToF-AMS), Scanning Mobility Particle Sizing (SMPS), and UV-vis spectroscopy. The molecular analysis of these aerosols provides valuable insight to the formation and photochemical behavior of unexpected, polymeric, light absorbing, and unique organosulfur species.
