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vls/2603noah-balancer_mdapi1elekpub.bib.uni-wuppertal.devdDevelopment and characterization of the airborne chemical ionization mass spectrometer FunMass-C for atmospheric trace gas measurementsAlber, SaschaVerfasserautBenter, Thorsten1962-Akademischer BetreuerdgsBergische Universität WuppertalGrad-verleihende InstitutiondggtextthesisTextHochschulschriftthesisdoctoralThesisgwXA-DEWuppertal2025single unitengelectronic resourceremotetext/htmltext/html1 Online-Ressource (xli, 265 Seiten) : Illustrationen, DiagrammeComputerOnline-RessourceThis dissertation focuses on the further development and comprehensive characterization ofthe state-of-the-art airborne chemical ionization mass spectrometer FunMass-C. FunMass-C was specifically developed for the regular in-situ measurement of various trace gases inthe upper troposphere and lower stratosphere (UTLS). These include sulfur dioxide (SO2),hydrogen cyanide (HCN), other inorganic and organic acids, and hydroperoxides. Startingin 2026, FunMass-C will be deployed on a Lufthansa Airbus A350 as part of the IAGOS-CARIBIC infrastructure to provide global, high-resolution atmospheric data.The work describes the new development and optimization of central FunMass-C com-ponents, including the Ion-Molecule Reaction (IMR) zone and the ion source (IS), which isbased on vacuum UV lamps. Trifluoromethoxide (CF3O-) is primarily used as the reagention for chemical ionization.Some materials were tested as scrubbers to selectively remove SO2 and HCN from thesample air, while keeping other conditions, especially water vapor content, as constant aspossible.The positive ionization mode with benzene (C6H6+) as the reagent ion also enabled thedetection of dimethyl sulfide (DMS) and ammonia (NH3).FunMass-C achieves high sensitivity in the order of 10-5 ncps · ppt-1 and low detectionlimits (LOD(2σ, 10 s) of 2 to 9 ppt) for most target species (SO2, HCN, formic acid (HCOOH),acetic acid (CH3COOH), and hydrogen chloride (HCl)). For DMS in the positive mode, anLOD(2σ, 10 s) of 0.6 ppt was achieved. The influence of water vapor and ozone on sensitivityand LODs was studied in detail. Water vapor and ozone mainly lead to a decrease in sensitivityand an increase in signal noise. Isobaric interferences, such as that of HCOOH on the SO2 signal or SO2 on the HCN signal, were quantified. These interferences can significantlyaffect measurement accuracy and require corresponding corrections, especially with increasedhumidity or ozone concentration.Theoretical calculations of the ion chemistry of CF3O- showed that weak acids preferen-tially form CF3O- clusters, while strong acids lead to the protonation of CF3O- and subsequentcatalytic decomposition of CF3OH, with their fluoride clusters being detected. The decompo-sition of CF3OH can significantly be catalytically accelerated by water vapor and acids. Thiswill help to better understand ion reactions inside the IMR, which allows to predict potentialby-products and isobaric interferences.DMS oxidation experiments were a further focus of the work, conducted in the SAPHIR-STAR simulation chamber in 2023 and 2024. The oxidation of DMS was investigated underdry, humid, and NOx-influenced conditions. Hydroperoxymethylthioformate (HPMTF), animportant intermediate, was successfully detected using various CIMS techniques (NO3-, Br3-,I3- and CF3O-). The yields of SO2 and carbonyl sulfide (OCS) were determined under dryconditions, with values of 28–40 % S for SO2 and 3–5 % S for OCS.It was shown that increased humidity can increase the sensitivity of HPMTF up to afactor of 3 for CF3O-. The NOx experiments indicate that the NO3- and Br- modes ofthe Multi-scheme chemical ionization atmospheric-pressure-interface long-time-of-flight massspectrometer (MION API-LTOF) are strongly negatively affected by the addition of NO,therefore HPMTF measurement data from MION API-LTOF during NO addition cannot beused. An isobaric interference of N2O5 on HPMTF for the CF3O--CIMS (FunMass-C) was ruled out. A first estimate of the HPMTF calibration factor for FunMass was derived, whichis in the same order of magnitude (10-6 ncps · ppt-1) as that for H2O2.Alber, SaschaBergische Universität Wuppertal, Dissertation, 2026Chemische-Ionization MassenspektrometrieFlugzeugmessungen(Ultra-)SpurengaseFunMassChemical Ionization MassspectrometryAirborne Measurements(Ultra-)Trace GasesWuppertal541urn:nbn:de:hbz:468-2-722710.25926/BUW/0-103699377201835506441Development and characterization of the airborne chemical ionization mass spectrometer FunMass-C for atmospheric trace gas measurementsAlber, SaschaDruck-AusgabeHT031535696https://dx.doi.org/10.25926/BUW/0-1036https://nbn-resolving.org/urn:nbn:de:hbz:468-2-7227Open AccessCC BY 4.02026-02-11oaDoctoralThesispublic26062620260805095256.0CT009000536s2w-hsswupubwgerUBW:C https://elekpub.bib.uni-wuppertal.de//domainresource/static/graphics/connectors/viewerLogo.gifWuppertal : Bergische Universität Wuppertalcc-by https://ub-wuppertal.digibib.net/search/katalog/record/(DE-605)urn%3Anbn%3Ade%3Ahbz%3A468-2-7227 https://elekpub.bib.uni-wuppertal.de/id/8350946 https://elekpub.bib.uni-wuppertal.de/i3f/v20/8350946/manifest https://elekpub.bib.uni-wuppertal.de/proto_ftsearch/8350946