Hoyermann, Karlheinz

[["dc.bibliographiccitation.firstpage","625"],["dc.bibliographiccitation.journal","ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH IN PHYSICAL CHEMISTRY & CHEMICAL PHYSICS"],["dc.bibliographiccitation.lastpage","641"],["dc.bibliographiccitation.volume","214"],["dc.contributor.author","Beiderhase, T."],["dc.contributor.author","Hack, W."],["dc.contributor.author","Hoyermann, Karlheinz"],["dc.contributor.author","Olzmann, M."],["dc.date.accessioned","2018-11-07T11:17:32Z"],["dc.date.available","2018-11-07T11:17:32Z"],["dc.date.issued","2000"],["dc.description.abstract","Fluorinated hydrocarbon radical-radical reactions in the gas phase have been studied at low pressure (0.5 less than or equal to p/mbar less than or equal to 2) and low temperature (253 less than or equal to T/K less than or equal to 333) using the discharge flow reactor molecular beam sampling mass spectrometry (MS) technique. Stable and labile species have been detected by MS applying low energy electron impact as well as multiphoton ionisation. For the combination reaction (1) CH2F + CH2F --> products the rate coefficient k(1) = (7.0 +/- 0.8) . 10(12) (T/298)((-3.9+/-1.0)) cm(3)/mol . s was determined. At low pressure the HF elimination pathway (1b) (1b) CH2F + CH2F --> C2H3F + HF is the main channel (k(1b)/k(1) = (0.82 +/- 0.015)). For the CHF, radical self reaction (2) CHF2 + CHF2 --> products the rate coefficient was measured as k(2) = (1.7 +/- 0.5) . 10(13) exp((-555 +/- 89)/T) cm(3)/ mol . s. The stabilisation of C2H2F4 is the main reaction pathway (2a) (k(2a)/k(2) greater than or equal to 0.5), the HF elimination is of minor importance (k(2b)/k(2) = 0.2). No pressure dependence of k(1) and k(2) was observed in the limited pressure range."],["dc.identifier.doi","10.1524/zpch.2000.214.5.625"],["dc.identifier.isi","000087622100006"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/54830"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Oldenbourg Verlag"],["dc.relation.issn","0942-9352"],["dc.title","Gas-phase kinetics of the self reactions of the radicals CH2F and CHF2"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","2365"],["dc.bibliographiccitation.issue","12"],["dc.bibliographiccitation.journal","Physical Chemistry Chemical Physics"],["dc.bibliographiccitation.lastpage","2371"],["dc.bibliographiccitation.volume","3"],["dc.contributor.author","Hack, W."],["dc.contributor.author","Hoyermann, Karlheinz"],["dc.contributor.author","Kersten, C."],["dc.contributor.author","Olzmann, M."],["dc.contributor.author","Viskolcz, B."],["dc.date.accessioned","2018-11-07T09:38:19Z"],["dc.date.available","2018-11-07T09:38:19Z"],["dc.date.issued","2001"],["dc.description.abstract","The 1-C4H9 + O reaction has been investigated in two quasi-static reactors with different detection systems. From a time-resolved measurement of OH formation by laser induced fluorescence (T = 295 K, p = 21 mbar, bath gas: He) an inverted vibrational state distribution for OH X (2)Pi (v = 0, 1, 2) was observed. By using Fourier transform infrared spectroscopy, relative product yields of 0.55 +/- 0.08 for 1-C4H8, 0.397 +/- 0.05 for HCHO and 0.053 +/- 0.02 for C3H7CHO were determined (T = 298 K, p = 2 mbar, bath gas: He). The results are explained in terms of the formation and subsequent decomposition of an intermediate chemically activated 1-C4H9O radical and a competing abstraction channel leading directly to OH + 1-C4H8. A modeling by statistical rate theory based on ab initio results for the stationary points of the potential energy surface of C4H9O allows the quantitative description of the product branching ratios. From this modeling, threshold energies of E-06 = 55 +/- 6 and E-07 = 88 +/- 6 kJ mol(-1) for the beta -C-C and the beta -C-H bond dissociation, respectively, in 1-C4H9O are obtained. For the 1,5 H atom shift, a most probable value of E-05 = 40 +/- 5 kJ mol(-1) follows from a comparison of our quantum chemical results with data from the literature."],["dc.identifier.doi","10.1039/b100149n"],["dc.identifier.isi","000169504900024"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/33043"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Royal Soc Chemistry"],["dc.publisher.place","Cambridge"],["dc.relation.conference","International Discussion Meeting of the Deutsche-Bunsen-Gesellschaft-fur-Physikalische-Chemie"],["dc.relation.eventlocation","GOTTINGEN, GERMANY"],["dc.relation.issn","1463-9076"],["dc.title","Mechanism of the 1-C4H9+O reaction and the kinetics of the intermediate 1-C4H9O radical"],["dc.type","conference_paper"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1005"],["dc.bibliographiccitation.journal","Proceedings of the Combustion Institute"],["dc.bibliographiccitation.lastpage","1013"],["dc.bibliographiccitation.volume","30"],["dc.contributor.author","Hack, W."],["dc.contributor.author","Hoyermann, Karlheinz"],["dc.contributor.author","Olzmann, M."],["dc.contributor.author","Viskolcz, B."],["dc.contributor.author","Wehmeyer, Jens"],["dc.contributor.author","Zeuch, Thomas"],["dc.date.accessioned","2018-11-07T08:47:00Z"],["dc.date.available","2018-11-07T08:47:00Z"],["dc.date.issued","2005"],["dc.description.abstract","The reactions of the branched primary alkyl radicals iso-butyl and neo-pentyl radicals with atomic oxygen at room temperature and low pressure have been studied with respect to the mechanism of the multiple reaction channels and the rate coefficients. The primary products and the yield of the reaction channels have been determined by quantitative FTIR spectroscopy using laser flash photolysis for the production of the radicals and atoms (iSO-C4H10 + Cl, neo-C5H2 + Cl; Cl from the photolysis of CFCl3, O from SO2)- In an independent experimental arrangement of a conventional discharge flow reactor with molecular beam sampling, the hydrocarbon radicals were detected mass spectrometrically after specific laser induced multiphoton ionization, thus allowing the measurement of the rate coefficients with reference to the reaction C2H5 + O(k = 1.04 x 10(14) cm(3)/mol s). Both reactions show multichannel behaviour via the formation of a highly excited alkoxy radical followed by C-C and C-H bond cleavage and, in the case Of iso-C4H9 with a hydrogen atom in the 2-position, a direct abstraction to OH radicals: GRAPHICS The experimental results for the branching ratio for the C-C and C-H cleavage in the alkoxy intermediate are discussed in terms of statistical rate theory. (c) 2004 The Combustion Institute. Published by Elsevier Inc. All rights reserved."],["dc.identifier.doi","10.1016/j.proci.2004.08.072"],["dc.identifier.isi","000229944200107"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/20836"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Science Inc"],["dc.publisher.place","New york"],["dc.relation.conference","30th International Symposium on Combustion"],["dc.relation.eventlocation","Univ Illinois Chicago, Chicago, IL"],["dc.relation.issn","1540-7489"],["dc.title","The reactions of the branched alkyl radicals iso-butyl and neo-pentyl with oxygen atoms - an experimental and theoretical study"],["dc.type","conference_paper"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","493"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH IN PHYSICAL CHEMISTRY & CHEMICAL PHYSICS"],["dc.bibliographiccitation.lastpage","510"],["dc.bibliographiccitation.volume","218"],["dc.contributor.author","Beiderhase, T."],["dc.contributor.author","Hoyermann, Karlheinz"],["dc.contributor.author","Nothdurft, J."],["dc.contributor.author","Olzmann, M."],["dc.date.accessioned","2018-11-07T10:53:21Z"],["dc.date.available","2018-11-07T10:53:21Z"],["dc.date.issued","2004"],["dc.description.abstract","The mechanisms and the rates of the reactions of the fluorinated hydrocarbon radical CH2F with the fluorinated and pure hydrocarbon radicals CHF2 CH2, and C2H5, respectively, have been studied at low pressure (around 2 mbar) and room temperature using the discharge-flow reactor technique. Mass spectrometry either with electron impact or laser induced multiphoton ionization was applied for the detection of labile and stable species. The cross combination of the radicals is mainly followed by HF elimination from the chemically activated adduct. The overall rate coefficients at 298 K for CH2F + CHF2 --> C2H2F2 + HF (1) CH2F + CH3 --> C2H4 + HF (2) CH2F + C2H5 --> C3H6 + HF (3) were derived from the analysis of the radical-time profiles by fit procedures; the following values were obtained: k(1) = (3.0 + 1.5/ - 0.7) x 10(12) cm(3) mol(-1) s(-1) k(2) = (4.0 +/- 1.5) x 10(12) cm(3) mol(-1) s(-1). k(3) = (9.0 +/- 3) x 10(12) cm(3) mol(-1) s(-1). The results are discussed in terms of chemical activation mechanisms."],["dc.identifier.doi","10.1524/zpch.218.4.493.29203"],["dc.identifier.isi","000221221900010"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/49347"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Oldenbourg Verlag"],["dc.relation.issn","0942-9352"],["dc.title","Gas-phase kinetics of the reactions of the CH2F radicals with the radicals CHF2, CH3, and C2H5"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1247"],["dc.bibliographiccitation.journal","Proceedings of the Combustion Institute"],["dc.bibliographiccitation.lastpage","1255"],["dc.bibliographiccitation.volume","29"],["dc.contributor.author","Hack, W."],["dc.contributor.author","Hoyermann, Karlheinz"],["dc.contributor.author","Olzmann, M."],["dc.contributor.author","Zeuch, Thomas"],["dc.date.accessioned","2018-11-07T10:33:42Z"],["dc.date.available","2018-11-07T10:33:42Z"],["dc.date.issued","2002"],["dc.description.abstract","The mechanisms and rates of the reactions of the primary alkyl radicals ethyl and I-propyl with oxygen atoms at room temperature and low pressure (around 5 mbar) have been studied using two independent experimental arrangements. The reactants were generated by UV-laser flash photolysis with different precursors (C2H5COC2H5, C2H6 + CFCl3, C2H5I, C3H7COC3H7, SO2). Stable species concentrations were measured quantitatively by Fourier transform IR and OH radical concentrations of the ground (V = 0) and first vibrational (v = 1) state by time-resolved laser-induced fluorescence. For both reaction 1 and reaction 2, the mechanism is explained in terms of the formation and subsequent decomposition of a chemically activated alkoxy radical and a competing abstraction channel leading directly to OH and the alkene: C2H5 + O --> C2H5O (reaction 1a)/C2H5O --> HCHO + CH3 (reaction 1a(1))/CH3CHO + H (reaction 1a(2))//C2H5 + O --> C2H4 + OH (reaction 1b). The absolute branching ratio was determined preferentially using diethyl ketone as the C2H5 radical source leading to (1a(1))/(1a(2))/(1b), 32/44/24. Relative branching ratios for the C2H5 radical sources C2H6 + Cl and C2H5I were derived as (1a(1))/(1a(2)) = 1/1.5 and 1/1.55, respectively. The overall rate coefficient of the reaction C2H5 + O was measured as k(1) = (1.04 +/- 0.1) X 10(14) cm(3) mol(-1) s(-1) and in addition k(C2H5 + OH) = (7.0 +/- 1) X 10(13) cm(3) mol(-1) s(-1). The mechanism and the rate of reaction 2 were found as 1-C3H7 + O --> 1-C3H7O (reaction 2a)/I-C3H7O --> HCHO + C2H5 (reaction 2a(1))/C2H5CHO + H (reaction 2a(2))//1-C3H7 + O --> C3H6 + OH (reaction 2b) (branching ratio (2a(1))/(2a(2))/(2b), 44/ 32/ 24) and k(2) = (8.2 +/- 1) X 10(13) cm(3) mol(-1) s(-1). The results are discussed in terms of statistical rate theory."],["dc.identifier.doi","10.1016/S1540-7489(02)80154-7"],["dc.identifier.isi","000182866100150"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/44674"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Combustion Inst"],["dc.publisher.place","Pittsburgh"],["dc.relation.conference","29th International Combustion Symposium"],["dc.relation.eventlocation","HOKKAIDO UNIV, SAPPORO, JAPAN"],["dc.relation.issn","0082-0784"],["dc.title","Mechanisms and rates of the reactions C2H5+O and 1-C3H7+O"],["dc.type","conference_paper"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","3165"],["dc.bibliographiccitation.issue","9"],["dc.bibliographiccitation.journal","The Journal of Physical Chemistry A"],["dc.bibliographiccitation.lastpage","3173"],["dc.bibliographiccitation.volume","110"],["dc.contributor.author","Hoyermann, Karlheinz"],["dc.contributor.author","Nothdurft, J."],["dc.contributor.author","Olzmann, M."],["dc.contributor.author","Wehmeyer, Jens"],["dc.contributor.author","Zeuch, Thomas"],["dc.date.accessioned","2018-11-07T10:06:56Z"],["dc.date.available","2018-11-07T10:06:56Z"],["dc.date.issued","2006"],["dc.description.abstract","The formation and the decomposition of chemically activated cyclopentoxy radicals from the C-C5H9 + O reaction have been studied in the gas phase at room temperature. Two different experimental arrangements have been used. Arrangement A consisted of a laser-flash photolysis set up combined with quantitative Fourier transform infrared spectroscopy and allowed the determination of the stable products at 4 mbar. The c-C5H9 radicals were produced via the reaction c-C5H10 + Cl with chlorine atoms from the photolysis of CFCl3; the O atoms were generated by photolysis of SO2. Arrangement B, a conventional discharge flow-reactor with molecular beam sampling, was used to determine the rate coefficient. Here, the hydrocarbon radicals (c-C5H9, C2H5, CH2OCH3) were produced via the reaction of atomic fluorine with c-C5H10, C2H6, and CH3OCH3, respectively, and detected by mass spectrometry after laser photoionization. For the c-C5H9 + 0 reaction, the relative contributions of intermediate formation (c-C5H9O ) and direct abstraction (C-C5H8 + OH) were found to be 68 +/- 5 and 32 +/- 4%, respectively. The decomposition products of the chemically activated intermediate could be identified, and the following relative branching fractions were obtained: C-C5H8O + H (31 +/- 2%), CH2CH(CH2)(2)CHO + H (40 +/- 5%), 2 C2H4 + H + CO (17 +/- 5%), and C3H4O + C2H4 + H (12 +/- 5%). Additionally, the product formation of the C-C5H8 + 0 reaction was studied, and the following relative yields were obtained (mol %): C2H4, 24%; C3H4O, 18%; c-C5H8O, 30%; c-C5H8O, 23%; 4-pentenal, 5%. The rate coefficient of the c-C5H9 + O reaction was determined relative to the reactions C2H5 + 0 and CH3OCH2 + O leading to k = (1.73 +/- 0.05) x 10(14) cm(3) mol(-1) s(-1). The experimental branching fractions are analyzed in terms of statistical rate theory with molecular and transition-state data from quantum chemical calculations, and high-pressure limiting Arrhenius parameters for the unimolecular decomposition reactions of C5H9O species are derived."],["dc.identifier.doi","10.1021/jp054578c"],["dc.identifier.isi","000235944000038"],["dc.identifier.pmid","16509640"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/39191"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Chemical Soc"],["dc.relation.issn","1089-5639"],["dc.title","Formation and decomposition of chemically activated cyclopentoxy radicals from the c-C5H9+O reaction"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]