Vacuum-UV- (VUV-) Photochemically Initiated Oxidation of Dimethylamine in the Gas Phase

Fethi, Fouad; López‐Gejo, Juan; Köhler, M.; Braun, André M.

doi:10.1515/jaots-2008-0204

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“…47 The reaction network (reactions (13a-e) in Scheme 2) is taken from a detailed analysis of the products upon photo-fragment translational spectroscopy (λ exc : 193 nm). 48 All reactions are subsequent to the formation of 5 (reaction (13), formation of sulfur (reaction (13a)) and elimination of 8 (reaction (13b)) being most favored, whereas the homolysis of hydrogen was excluded. 48,49 In O 2 -containing gas phases, intermediate C-and S-centered radicals are trapped yielding the corresponding peroxyl radicals (reaction (14), see section 1.3.…”

Section: Vuv-photolysismentioning

confidence: 99%

“…The C-and S-centered radicals formed in reactions (3), (11), (13) and (13b-d) may react with O 2 to form peroxyl radicals (reaction (14)) which are considered to be the key intermediates Fig. 1 VUV-and UVC-spectrum of gaseous thiophene (TP), adapted from.…”

Section: Vuv-photochemical Oxidation and Mineralizationmentioning

confidence: 99%

“…2,3, and the combination of the two methods of air treatment might have a very high application potential for the abiotic treatment of polluted air. [4][5][6][7][8][9][10] After exploring the VUV-photochemical oxidation of hydrocarbons, halogen as well as N-and O-containing organic substrates chosen as model pollutants, [11][12][13][14][15][16] this work focuses on thiophene (TP, Scheme 1) as a S-containing organic compound. Among the different volatile organic compounds (VOCs) present in industrial and urban emissions, TP is one of the most important because of its presence in fossil fuels, e.g.…”

Section: Introductionmentioning

confidence: 99%

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Continuous process of the vacuum ultraviolet- (VUV-) photochemical oxidation of thiophene in the gas phase

Andriampanarivo

Köhler

López‐Gejo

et al. 2015

Photochem Photobiol Sci

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Thiophene was taken as a model compound for investigations on the efficiency of a continuous process of the vacuum-ultraviolet- (VUV-) photochemically initiated oxidation and mineralization of sulfur containing organic compounds in the gas phase. In the presence of molecular oxygen, atomic oxygen and ozone were photochemically generated and are assumed to initiate or participate in the (thermal) oxidation network. Addition of water vapor for an additional initiation of the oxidation by hydroxyl radicals did not accelerate the process. For comparison, thiophene was exposed to ozone and oxidized under otherwise the same experimental conditions, but complete mineralization was only found in the photochemical process and for relatively small concentrations of the substrate. The result may be explained by low rates of secondary thermal reactions of a number of identified intermediate products. Combining already published results and mechanistic hypotheses with the results of the present work, pathways of oxidative degradation are proposed. The photolysis of thiophene in molecular nitrogen confirmed earlier findings.

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Section: Vuv-photolysismentioning

confidence: 99%

Section: Vuv-photochemical Oxidation and Mineralizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Continuous process of the vacuum ultraviolet- (VUV-) photochemical oxidation of thiophene in the gas phase

Andriampanarivo

Köhler

López‐Gejo

et al. 2015

Photochem Photobiol Sci

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A Reflectron Time-of-Flight Mass Spectrometric Study on the Degradation Pathways of Glycine on Mars in the Presence of Perchlorates and Ionizing Radiation

Góbi

Förstel

Maksyutenko

et al. 2017

ApJ

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The absence of abundant organics on the Martian surface is a much discussed observation. So far, no explanation is completely satisfactory. In this study we aim for a deeper understanding of the degradation processes of organics in the presence of perchlorates that can take place on the Martian surface. Our primary goal is to study the radiation-induced decomposition process of glycine (H2NCH2COOH) in the absence and presence of an oxidizer relevant to the Martian surface—perchlorate anions ( ClO 4 − ) . Glycine and various samples of glycine-1-13C (+H3NC H 2 13 COO−)–magnesium perchlorate hexahydrate (Mg(ClO4)2 · 6H2O) were exposed to energetic electrons mimicking secondary electrons originating from the interaction of galactic cosmic rays (GCRs) with the Martian regolith. Using isotope-labeled and deuterated pure glycine samples such as glycine-1-13C, glycine-d5 (+D3NCD2COO−), glycine-N,N,N-d3 (+D3NCH2COO−), and glycine-2,2-d2 (+H3NCD2COO−), we can conclude that decarboxylation (carbon dioxide loss) of the glycine molecule is exclusively the first decay step during irradiation regardless of whether perchlorate anions are present or not. In pure glycine samples, the decarboxylation co-product methylamine (CH3NH2) and its radiolytic decay product ammonia could both be detected explicitly for the first time. In the presence of perchlorates, (partial) oxidation of the glycine decarboxylation product CH3NH2 may occur. Because the decarboxylation is an equilibrium reaction and the CH3NH2 is effectively removed from the system by this oxidation, glycine cannot be recycled. Therefore the depletion of the CH3NH2 facilitates the process, resulting in an overall 10-fold increase in the formation rate of carbon dioxide and its elevated concentrations in the perchlorate-containing irradiated samples.

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Vacuum-UV- (VUV-) Photochemically Initiated Oxidation of Dimethylamine in the Gas Phase

Cited by 1 publication

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Continuous process of the vacuum ultraviolet- (VUV-) photochemical oxidation of thiophene in the gas phase

Continuous process of the vacuum ultraviolet- (VUV-) photochemical oxidation of thiophene in the gas phase

A Reflectron Time-of-Flight Mass Spectrometric Study on the Degradation Pathways of Glycine on Mars in the Presence of Perchlorates and Ionizing Radiation

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