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7. Experimental characterization of the chemical composition and structure of molecular soot precursors and soot particles in a laminar diffusion flame by coupling ToF-SIMS and Raman spectroscopy

Author

Elias, Jessy, Faccinetto, Alessandro, Irimiea, Cornelia, Nuns, Nicolas, Pirim, Claire, Focsa, Cristian, Mercier, Xavier, Physicochimie des Processus de Combustion et de l’Atmosphère - UMR 8522 (PC2A), Université de Lille-Centre National de la Recherche Scientifique (CNRS), DMPE, ONERA, Université Paris Saclay [Palaiseau], ONERA-Université Paris-Saclay, Institut Michel Eugène Chevreul - FR 2638 (IMEC), Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), and Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 (PhLAM)

Subjects
[CHIM]Chemical Sciences
Abstract

International audience; The transformation process in sooting flames leading to the formation of nanoparticles in the condensed phase from molecular precursors in the gas phase (soot nucleation) is not yet fully understood [1]. Information on the physical chemical properties of the nascent particles is difficult to accessexperimentally but also essential for the validation of the hypotheses on soot nucleation currently being examined by the scientific community. In this work, we characterize the molecular precursors and the soot particles formed in a laminar diffusion methane flame by combining several in situ and ex situ diagnostics (fluorescence, incandescence, secondary ion mass spectrometry and Raman spectroscopy) with the goal of inferring the chemical composition and the structure of the nascent particles. The presented work highlights that several of the investigated physical chemical properties suddenly change within a narrow flame region that acquires the character of a discontinuity point correlated to the soot nucleation process. Notably, the obtained data shows evidences of the transition from flat to curved molecular structures, and the progressive apparition of finite size, sandwiched graphene like layers. Furthermore, the fraction of atomic hydrogen features a local maximum immediately upstream the detection of nascent soot particles consistent with the increasing in flame rate of C-C covalent bonds formation postulated by the major hypotheses explaining the nucleation of soot particles.References[1] J.W. Martin, M. Salamanca, M. Kraft, Soot inception: Carbonaceous nanoparticle formation in flames, Progress in Energy and Combustion Science. 88 (2022) 100956.https://doi.org/10.1016/j.pecs.2021.100956.

Published
2022

10. Preliminary results on the chemical composition of the Lepidorhombus boscii (Risso, 1810) otolith from the Adriatic sea

Author

Ugrin, Nika, Mitra, Tirthankar, Carpentier, Yvain, Pirim, Claire, Salamon, Krešimir, Jakovljević, Suzana, Vojković, Marin, Cristian Focsa, Krstulović Šifner, Svjetlana, Ivanić, Maja, Fiket, Željka, Furdek Turk, Martina, and Vdović Neda

Subjects
Lepidorhombus boscii, Adriatic sea, otolith, scanning electron microscopy, X-ray diffraction, mass spectrometry
Abstract

Otoliths are a part of the fish inner ear involved in sound reception, balance perception and orientation. Saggital otoliths of teleost fish mainly consist of calcium carbonate in the form of aragonite. However, there are abnormal otoliths that contain other polymorphs, such as calcite, vaterite or their combinations. This preliminary study represents the first record and investigation of Lepidorhombus boscii otoliths including those irregularly shaped and characterized by surface deformations. These can arise due to stressful conditions, high population density, temperature fluctuations, disease or pollution, which can cause structural or physiological changes that affect the formation of otoliths. In addition to morphological features, polymorphs of calcium carbonate have an influence on the elemental composition of otoliths. The morphology and chemical composition of L. boscii saggital otolith were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and by two step laser desorption ionization mass spectrometry (L2MS). L2MS was used to analyse the surface chemical composition of the otoliths, confirming the presence of inorganic and organic compounds in the otolith matrix. Tuning the desorption fluencies to maximize the metal containing components (K, Ca, Cu, Ag, Sr), shows an abundance of pure metallic, oxidized and hydroxidized species. XRD was used to analyse the crystal structure, while SEM was used to photograph the surfaces of normal and abnormal otoliths (aragonite and calcite) between males and females. This research provided a preliminary insight into the concentrations of chemical elements deposited on the otoliths of individuals of this species in the central Adriatic Sea. Although the number of analyzed samples is small, the results are promising. They represent a starting point for the future research, that should be based on a larger number of samples from more locations These results could be used to get a better insight into movement patterns and possibly for determination of the origin of this species.

Published
2022

11. Revealing the origin of chemical complexity in extraterrestrial matter by combining multiple characterization techniques: HR-L2MS, TOF-SIMS, and micro-Raman spectroscopy: Invited talk

Author

Pirim, Claire, Dumitru, Duca, Slavicinska, Katerina, Ferrari, Brian, Carpentier, Yvain, Vojkovic, Marin, Chazallon, Bertrand, Focsa, Cristian, Bennett, Christopher J., Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 (PhLAM), Université de Lille-Centre National de la Recherche Scientifique (CNRS), Physique Moléculaire aux Interfaces (PMI), Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), and University of Central Florida [Orlando] (UCF)

Subjects
[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, [PHYS]Physics [physics], Astrochemistry -meteorites, [SDU]Sciences of the Universe [physics], Mass spectrometry imaging techniques, Micro-Raman Spectroscopy, Laser desorption ionization mass spectrometry, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Secondary ion mass spectrometry SIMS, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2021

12. Chemical differentiation of the solid and gas-phase fractions in combustion exhausts using a two-filter collection system and mass spectrometry techniques

Author

Carpentier, Yvain, Ngo, Linhdan, Dimitriu, Duca, Pirim, Claire, Vojkovik, M., Noble, Jennifer, Irimiea, Cornelia, Faccinetto, Alessandro, Therssen, Eric, Yon, Jerôme, Nuns, Nicolas, Focsa, Cristian, Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 (PhLAM), Université de Lille-Centre National de la Recherche Scientifique (CNRS), Physique Moléculaire aux Interfaces (PMI), Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), DMPE, ONERA, Université Paris Saclay (COmUE) [Palaiseau], ONERA-Université Paris Saclay (COmUE), Physicochimie des Processus de Combustion et de l’Atmosphère - UMR 8522 (PC2A), Complexe de recherche interprofessionnel en aérothermochimie (CORIA), Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Université de Lille, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), and Normandie Université (NU)

Subjects
[SPI]Engineering Sciences [physics], [SPI.FLUID]Engineering Sciences [physics]/Reactive fluid environment, [CHIM]Chemical Sciences, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2020

13. Multi-technique physico-chemical characterization of particles generated by a gasoline engine: Towards measuring tailpipe emissions below 23 nm

Author

Noble, J.A., Betrancourt, C., Tritscher, T., Spielvogel, J., Rahman, M., Boies, A., Lee, K.F., Bhave, A.N., Legendre, S., Lancry, O., Kreutziger, P., Rieker, M., Minutolo, Patrizia, Commodo, Mario, D’Anna, Andrea, Nuns, Nicolas, Desgroux, Pascale, Mercier, Xavier, Ngo, Linh Dan, Duca, Dumitru, Carpentier, Yvain, Noble, Jennifer, Ikhenazene, Raouf, Vojkovic, Marin, Irimiea, Cornelia, Ortega, Ismael, Lefevre, Guillaume, Yon, Jérôme, Faccinetto, Alessandro, Therssen, Eric, Ziskind, Michael, Chazallon, Bertrand, Pirim, Claire, Focsa, Cristian, Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 (PhLAM), Université de Lille-Centre National de la Recherche Scientifique (CNRS), Physique Moléculaire aux Interfaces (PMI), Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Physicochimie des Processus de Combustion et de l’Atmosphère - UMR 8522 (PC2A), Laboratory of Atmospheric Chemistry [Paul Scherrer Institute] (LAC), Paul Scherrer Institute (PSI), International Islamic University Malaysia [Kuala Lumpur], HORIBA Scientific [France], Laboratoire Avancé de Spectroscopie pour les Intéractions la Réactivité et l'Environnement - UMR 8516 (LASIRE), Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Centrale Lille Institut (CLIL), ANR-11-LABX-0005,Cappa,Physiques et Chimie de l'Environnement Atmosphérique(2011), Centre National de la Recherche Scientifique (CNRS)-Université de Lille, Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Moléculaires (ISM), Université Montesquieu - Bordeaux 4-Université Sciences et Technologies - Bordeaux 1-École Nationale Supérieure de Chimie et de Physique de Bordeaux (ENSCPB)-Centre National de la Recherche Scientifique (CNRS), International Centre for Diarrhoeal Disease Research, International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B), Laboratoire de Spectrochimie Infrarouge et Raman - UMR 8516 (LASIR), Université de Lille, Sciences et Technologies, DMPE, ONERA, Université Paris Saclay (COmUE) [Palaiseau], Université Paris Saclay (COmUE)-ONERA, Complexe de recherche interprofessionnel en aérothermochimie (CORIA), Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), and Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Internal combustion engine, Nanoparticles, Physico-chemical characterization, Mass spectrometry, Emission modeling, Context (language use), 010501 environmental sciences, 01 natural sciences, 7. Clean energy, Ultrafine particle, Process engineering, Gasoline direct injection, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, General Environmental Science, Petrol engine, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [PHYS.PHYS]Physics [physics]/Physics [physics], [CHIM.ORGA]Chemical Sciences/Organic chemistry, business.industry, Particulates, Characterization (materials science), 13. Climate action, Environmental science, Particle, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], business
Abstract

Particulate emissions from on-road motor vehicles are the focus of intensive current research due to the impact of the ambient particulate matter (PM) levels on climate and human health. Constant improvement in engine technology has led to significant decrease in the number and mass of emitted PM, but particular concern is raised nowadays by the ultrafine particles. In this context, there is a critical lack of certification procedures for the measurement of the smallest-size ( 23 nm) particulate matter emissions. To support the engine development process as well as future certification procedures, a measurement technology for sub-23 nm particles must be designed. The development of a reliable measurement procedure entails understanding the formation and evolution of particles from the engine to the tailpipe via multiple analytical techniques and theoretical simulations. We present here extensive experimental characterization of ultrafine particles emitted by a gasoline direct injection single-cylinder engine as particle generator. The particles were sampled using a cascade impactor which allows size-separation into 13 different size bins. Chemical characterization of the collected size-selected particles was performed using mass spectrometry, which gives access to detailed molecular information on chemical classes of critical interest such as organosulphates, oxygenated hydrocarbons, nitrogenated hydrocarbons, metals, or polycyclic aromatic hydrocarbons. Additionally, the morphology of the emitted particles was probed with atomic force (AFM) and scanning electron microscopy (SEM). Tip-Enhanced Raman Spectroscopy (TERS) was applied for the first time to sub-10 nm combustion-generated particles to gather information on their nanostructure. The extensive database built from these multiple experimental characterizations has been used as input of a theoretical approach to simulate and validate engine out-emissions. These studies were performed in the framework of the H2020 PEMS4Nano project which aims to the development of a robust, reliable and reproducible measurement technology for particles down to 10 nm for both chassis dyno and real driving emissions (RDE).

Published
2020
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14. Chemical discrimination of the particulate and gas phases of miniCAST exhausts using a two-filter collection method

Author

Ngo, Linh Dan, primary, Duca, Dumitru, additional, Carpentier, Yvain, additional, Noble, Jennifer A., additional, Ikhenazene, Raouf, additional, Vojkovic, Marin, additional, Irimiea, Cornelia, additional, Ortega, Ismael K., additional, Lefevre, Guillaume, additional, Yon, Jérôme, additional, Faccinetto, Alessandro, additional, Therssen, Eric, additional, Ziskind, Michael, additional, Chazallon, Bertrand, additional, Pirim, Claire, additional, and Focsa, Cristian, additional

Published
2020
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15. Particulate and Gas Phase Separation in Simultaneous Sampling of Combustion Byproducts: New Insights into Chemical Composition by Mass Spectrometric Analysis

Author

Noble, Jennifer, Ngo, Linhdan, Dumitru, Duca, Vojkovic, Marin, Raouf Ikhenazene, Abd, Irimiea, Cornelia, Lefevre, Guillaume, Faccineto, Alessandro, Pirim, Claire, Carpentier, Yvain, Therssen, Eric, Chazallon, Bertrand, Nuns, Nicolas, Yon, Jerôme, Focsa, Cristian, Institut des Sciences Moléculaires (ISM), Université Montesquieu - Bordeaux 4-Université Sciences et Technologies - Bordeaux 1-École Nationale Supérieure de Chimie et de Physique de Bordeaux (ENSCPB)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Physicochimie des Processus de Combustion et de l’Atmosphère - UMR 8522 (PC2A), Université de Lille-Centre National de la Recherche Scientifique (CNRS), Institut Lumière Matière [Villeurbanne] (ILM), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 (PhLAM), Institut des Molécules et de la Matière Condensée de Lille (IMMCL), Centrale Lille Institut (CLIL)-Centre National de la Recherche Scientifique (CNRS)-Université de Lille, Sciences et Technologies, Complexe de recherche interprofessionnel en aérothermochimie (CORIA), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), Université Montesquieu - Bordeaux 4-Université Sciences et Technologies - Bordeaux 1 (UB)-École Nationale Supérieure de Chimie et de Physique de Bordeaux (ENSCPB)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Université de Lille, Sciences et Technologies-Centrale Lille-Centre National de la Recherche Scientifique (CNRS), Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), and Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SPI.FLUID]Engineering Sciences [physics]/Reactive fluid environment, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2018

17. Supplementary material to "Chemical discrimination of the particulate and gas phases of miniCAST exhausts using a two-filter collection method"

Author

Ngo, Linh Dan, primary, Duca, Dumitru, additional, Carpentier, Yvain, additional, Noble, Jennifer A., additional, Ikhenazene, Raouf, additional, Vojkovic, Marin, additional, Irimiea, Cornelia, additional, Ortega, Ismael K., additional, Lefevre, Guillaume, additional, Yon, Jérôme, additional, Faccinetto, Alessandro, additional, Therssen, Eric, additional, Ziskind, Michael, additional, Chazallon, Bertrand, additional, Pirim, Claire, additional, and Focsa, Cristian, additional

Published
2019
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18. Chemical discrimination of the particulate and gas phases of miniCAST exhausts using a two-filter collection method

Author

Ngo, Linh Dan, primary, Duca, Dumitru, additional, Carpentier, Yvain, additional, Noble, Jennifer A., additional, Ikhenazene, Raouf, additional, Vojkovic, Marin, additional, Irimiea, Cornelia, additional, Ortega, Ismael K., additional, Lefevre, Guillaume, additional, Yon, Jérôme, additional, Faccinetto, Alessandro, additional, Therssen, Eric, additional, Ziskind, Michael, additional, Chazallon, Bertrand, additional, Pirim, Claire, additional, and Focsa, Cristian, additional

Published
2019
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20. Glycoprofiling bifidobacterial consumption of galacto-oligosaccharides by mass spectrometry reveals strain-specific, preferential consumption of glycans

Author

Barboza, Mariana, Sela, David A., Pirim, Claire, LoCascio, Riccardo G., Freeman, Samara L., German, J. Bruce, Mills, David A., and Lebrilla, Carlito B.

Subjects
Bifidobacterium -- Genetic aspects, Bifidobacterium -- Physiological aspects, Fermentation -- Analysis, Galactose -- Chemical properties, Lasers -- Usage, Mass spectrometry -- Usage, Oligosaccharides -- Chemical properties, Laser, Biological sciences
Abstract

The role of galacto-oligosaccharides (GOS) as prebiotics is understood by preparing purified GOS (pGOS) without disaccharides and monosaccharides and it is used in bacterial fermentation experiments. The approach has shown that matrix-assisted laser desorption ionization-Fourier transform ion cyclotron resonance (MALDI-FTICR) is a rapid-throughput tool for comprehensive profiling of oligosaccharides in GOS mixtures.

Published
2009

21. Glycoprofiling of Bifidobacterial Consumption of Human Milk Oligosaccharides Demonstrates Strain Specific, Preferential Consumption of Small Chain Glycans Secreted in Early Human Lactation

Author

Pirim, Claire, LoCascio, Riccardo, Ninonuevo, Milady, Freeman, Samara, Sela, David, Grimm, Rudolf, Lebrilla, Carlito, Mills, David, German, J. Bruce, Department of Chemistry, University of California Davis, Institut für Quantenoptik und Quanteninformation, Department of Viticulture, and University of California

Subjects
Time Factors, Bifidobacterium longum, medicine.medical_treatment, Oligosaccharides, Breast milk, Sialidase, law.invention, 03 medical and health sciences, chemistry.chemical_compound, Probiotic, fluids and secretions, Species Specificity, Polysaccharides, law, Lactation, medicine, Humans, Lactose, ComputingMilieux_MISCELLANEOUS, 030304 developmental biology, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, chemistry.chemical_classification, 0303 health sciences, Milk, Human, biology, [SDE.IE]Environmental Sciences/Environmental Engineering, 030306 microbiology, Prebiotic, food and beverages, General Chemistry, Oligosaccharide, biology.organism_classification, medicine.anatomical_structure, chemistry, Biochemistry, Female, Bifidobacterium, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], General Agricultural and Biological Sciences
Abstract

The molecular basis by which human breast milk supports the development of a protective intestinal microbiome in infants is unknown. After lactose and lipids, human milk oligosaccharides (HMOs) are quantitatively the third largest and most diverse component of breast milk. In this work, glycomic profiling of HMO consumption by bifidobacteria using Fourier transform ion cyclotron resonance mass spectrometry reveals that one species, Bifidobacterium longum biovar infantis ATCC 15697, an isolate from the infant gut, preferentially consumes small mass oligosaccharides, representing 63.9% of the total HMOs available. These HMOs were detected in human breast milk at the onset and constantly through the first month of lactation by use of high performance liquid chromatography-chip time-of-flight mass spectrometry. Further characterization revealed that strain ATCC 15697 possesses both fucosidase and sialidase activities not present in the other tested strains. This work provides evidence that these small mass HMOs are selectively metabolized by select bifidobacterial strains and represent a potential new class of bioactive molecules functioning as prebiotics to facilitate a protective gut colonization in breast-fed newborns.

Published
2007
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23. Chemical discrimination of the particulate and gas phases of miniCAST exhausts using a two-filter collection method.

Author

Ngo, Linh Dan, Duca, Dumitru, Carpentier, Yvain, Noble, Jennifer A., Ikhenazene, Raouf, Vojkovic, Marin, Irimiea, Cornelia, Ortega, Ismael K., Lefevre, Guillaume, Yon, Jérôme, Faccinetto, Alessandro, Therssen, Eric, Ziskind, Michael, Chazallon, Bertrand, Pirim, Claire, and Focsa, Cristian

Subjects
SECONDARY ion mass spectrometry, QUARTZ, POLYCYCLIC aromatic hydrocarbons, CARBONACEOUS aerosols, ATMOSPHERIC chemistry, CRYSTAL filters, SURFACE chemistry
Abstract

Combustion of hydrocarbons produces both particulate and gas phase emissions responsible for major impacts on atmospheric chemistry and human health. Ascertaining the impact of these emissions, especially on human health, is not straightforward because of our relatively poor knowledge of how chemical compounds are partitioned between the particle and gas phases. Accordingly, we propose to couple a two-filter sampling method with a multi-technique analytical approach to fully characterize the particulate and gas phase compositions of combustion by-products. The two-filter sampling method is designed to retain particulate matter (elemental carbon possibly covered in a surface layer of adsorbed molecules) on a first quartz fiber filter while letting the gas phase pass through, and then trap the most volatile components on a second black carbon-covered filter. All samples thus collected are subsequently subjected to a multi-technique analytical protocol involving two-step laser mass spectrometry (L2MS), secondary ion mass spectrometry (SIMS), and micro-Raman spectroscopy. Using the combination of this two-filter sampling/multi-technique approach in conjunction with advanced statistical methods we are able to unravel distinct surface chemical compositions of aerosols generated with different set points of a miniCAST burner. Specifically, we successfully discriminate samples by their volatile, semi-volatile and non-volatile polycyclic aromatic hydrocarbon (PAH) contents and reveal how subtle changes in combustion parameters affect particle surface chemistry. [ABSTRACT FROM AUTHOR]

Published
2019
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30. RadiationProcessing of Formamide and Formamide:WaterIces on Silicate Grain Analogue.

Author

Dawley, M. Michele, Pirim, Claire, and Orlando, Thomas M.

Subjects
*FORMAMIDE, *SILICATES, *ELECTRON beams, *FOURIER transform infrared spectroscopy, *PHOTOLYSIS (Chemistry)
Abstract

Lyman-α (121.6 nm) photon and1 keV electron-beam irradiationof pure HCONH2(FA) ice and H2O:HCONH2ice mixtures on high-surface-area SiO2nanoparticleshave been investigated with FT-IR spectroscopy and temperature programmeddesorption (TPD). Lyman-α photolysis of pure amorphous FA icegrown at 70 K and crystalline FA ice produced by annealing to 165K gives spectral signatures between 2120 and 2195 cm–1that we assign primarily to OCN–and CO. The OCN–and CO yields are ∼25% less abundant for crystallineFA ice. Photon and electron processing also produces H2that is released from the ice between ∼90 and 140 K. A decreasein the H2TPD peak is seen for irradiated crystalline HCONH2ice. Lyman-α photolysis of H2O:HCONH2mixed ices increases OCN–and CO production,suggesting a catalytic role of H2O. Also, for pure FA,1 keV electron irradiation slightly increases the yield of OCN–, while CO decarboxylation is selectively prevented.CO is also not produced in H2O:HCONH2ices uponelectron irradiation. Dissociative ionization, direct dissociativeexcitation, and dissociative electron attachment (DEA) channels areaccessible in the Lyman-α (121.6 nm) photon and 1 keV electron-beamenergy range. DEA energetically favors OCN–andH–formation, with the latter leading to H2formation. The FA fragment product identities, yields, and branchingratios are considerably different relative to the gas phase and dependupon the radiation type, ice structure, and the presence of SiO2nanoparticles. The latter may increase ion–electronrecombination and radical recombination rates. The main products observedsuggest very different condensed-phase dissociation channels fromthose reported for gas-phase dissociation. Formation of ions/productsfrom FA is not negligible upon Lyman-α photolysis or electronirradiation, both of which could process ices in interstellar regionsas well as in Titan’s atmosphere. [ABSTRACT FROM AUTHOR]

Published
2014
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31. ThermalProcessing of Formamide Ices on Silicate GrainAnalogue.

Author

Dawley, M. Michele, Pirim, Claire, and Orlando, Thomas M.

Subjects
*FORMAMIDE, *SILICATES, *FOURIER transform infrared spectroscopy, *DESORPTION, *THERMAL properties
Abstract

Fourier transform-infrared spectroscopy(FT-IR) and temperatureprogrammed desorption (TPD) have been used to examine the thermalprocessing of three isotopes of pure formamide ice (HCONH2, DCONH2, and HCOND2) adsorbed on a SiO2interstellar grain analogue. Pure formamide ice on SiO2nanoparticles displays at least three different phases thatwe interpret as a porous phase from ∼70–145 K, a compactedpolycrystalline phase from ∼145–210 K, and a third slowdiffusion and sublimation phase from ∼210–380 K. Possibledimerization is also discussed. Formamide desorption from the SiO2grain surface is characterized by TPD of pure HCONH2and mixed H2O:HCONH2ices. Water desorbs at160 K, and formamide has a TPD peak maximum at ∼228 K. A mean Eactof ∼14.7 kcal/mol (0.64 eV) was obtainedusing Redhead analysis, indicating strong intermolecular forces withinformamide ice. The mixed H2O:HCONH2ice TPDdata suggests possible formamide accumulation if the grains are exposedto temperature cycles <180 K. [ABSTRACT FROM AUTHOR]

Published
2014
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32. Reactivity Between Non-EnergeticHydroxyl (OH) Radicalsand Methane (CH4).

Author

Zins, Emilie-Laure, Pirim, Claire, Joshi, Prasad Ramesh, and Krim, Lahouari

Subjects
*CHEMICAL reactions, *HYDROXYL group, *RADICALS (Chemistry), *METHANE, *TEMPERATURE measurements, *RING formation (Chemistry)
Abstract

Reactions between dilute methane and nonenergetic hydroxylradicalswere carried out at 3.5 K. The temperature was kept low in order tocharacterize the stepwise reaction and prevent parasitic side reactions.The hydroxyl radicals originate from discharged H2O/Hemixtures. The reactions were monitored in situ using a Fourier transforminfrared spectrometer. The formation of CH3radicals wasconfirmed simultaneously with the formation of water ice. Subsequentrecombination reactions lead to the formation of ethane (C2H6). Production of ethane and water ice occur preferentiallyto the formation of methanol. [ABSTRACT FROM AUTHOR]

Published
2012
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