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Lopes S, Nikitin T, Fausto R. Structural, spectroscopic, and photochemical study of ethyl propiolate isolated in cryogenic argon and nitrogen matrices. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2020; 241:118670. [PMID: 32679483 DOI: 10.1016/j.saa.2020.118670] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 06/25/2020] [Accepted: 06/27/2020] [Indexed: 06/11/2023]
Abstract
Ethyl propiolate (HC ≡ CCOOCH2CH3, EP) was studied experimentally by infrared spectroscopy in argon and nitrogen cryomatrices (15 K) and by quantum chemical calculations (at the DFT(B3LYP) and MP2 levels of theory). Calculations predict the existence of four conformers: two low-energy conformers (I and II) possessing the carboxylic moiety in the cis configuration (O=C-O-C dihedral equal to ~0°) and two higher-energy trans forms (O=C-O-C dihedral equal to ~180°; III and IV). The conformation of the ethyl ester group within each pair of conformers is either anti (C-O-C-C equal to 180°; in conformers I and III) or gauche (C-O-C-C equal to ±86.6° in II, and ± 92.5° in IV). The two low-energy cis conformers (I and II) were predicted to differ in energy by less than 2.5 kJ mol-1 and were shown to be present in the studied cryogenic matrices. Characteristic bands for each one of these conformers were identified in the infrared spectra of the matrix-isolated compound and assigned taking into account the results of normal coordinate analysis, which used the geometries and harmonic force constants obtained in the DFT calculations. The two trans conformers (III and IV) were estimated to be 17.5 kJ mol-1 higher in energy than the conformational ground state (form I) and were not observed experimentally. The unimolecular photochemistry of matrix-isolated EP (in N2 matrix) was also investigated. In situ irradiation with UV light (λ > 235 nm) leads mainly to decarbonylation of the compound, with generation of ethoxyethyne, which in a subsequent photoreaction generates ketene (plus ethene).
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Affiliation(s)
- S Lopes
- University of Coimbra, CQC, Department of Chemistry, 3004-535 Coimbra, Portugal.
| | - T Nikitin
- University of Coimbra, CQC, Department of Chemistry, 3004-535 Coimbra, Portugal; University of Coimbra, CFisUC, Department of Physics, 3004-516 Coimbra, Portugal
| | - Rui Fausto
- University of Coimbra, CQC, Department of Chemistry, 3004-535 Coimbra, Portugal.
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Teramoto T, Washida N, Imamura T, Inomata S. Rate Constants for Reactions of HCCO and HCCCO Radicals with O 2 over the Temperature Range 243-423 K. J Phys Chem A 2020; 124:4006-4014. [PMID: 32349472 DOI: 10.1021/acs.jpca.0c01322] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A pulsed laser photolysis-photoionization mass spectrometer system has been employed to measure the rate constants of HCCO + O2 and HCCCO + O2 over the temperature range 243-423 K in 1.2-8.4 Torr of He or N2. Radicals of HCCO and HCCCO were produced by 193 nm ArF laser photolysis of ethyl ethynyl ether and methyl propiolate, respectively. HCCO was photoionized by a Kr resonance lamp with a CaF2 window (10.03 eV), and HCCCO was ionized by a Xe lamp with a sapphire window (8.44 eV). Both ions were detected as parent ions in a quadrupole mass spectrometer. From analysis of the time profiles of the ion signals for various O2 concentrations, the overall rate constants at 298 K are represented by the values k2 = (6.3 ± 1.0) × 10-13 for HCCO + O2 and k5 = (5.7 ± 0.6) × 10-12 for HCCCO + O2 in the units cm3 molecule-1 s-1. The rate coefficients for the two reactions can be described by k2(T) = (1.5-0.7+1.5) × 10-12 exp[-(225 ± 220)/T] and k5(T) = (1.8-0.9+1.9) × 10-12 exp[(343 ± 228)/T] in the units cm3 molecule-1 s-1 over the temperature range 243-423 K.
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Affiliation(s)
- Takahiro Teramoto
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Nobuaki Washida
- National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
| | - Takashi Imamura
- National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
| | - Satoshi Inomata
- National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
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Adams JD, Scrape PG, Lee SH, Butler LJ. Dissociative Photoionization of the Elusive Vinoxy Radical. J Phys Chem A 2017; 121:6262-6268. [PMID: 28806080 DOI: 10.1021/acs.jpca.7b04730] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
These experiments report the dissociative photoionization of vinoxy radicals to m/z = 15 and 29. In a crossed laser-molecular beam scattering apparatus, we induce C-Cl bond fission in 2-chloroacetaldehyde by photoexcitation at 157 nm. Our velocity measurements, combined with conservation of angular momentum, show that 21% of the C-Cl photofission events form vinoxy radicals that are stable to subsequent dissociation to CH3 + CO or H + ketene. Photoionization of these stable vinoxy radicals, identified by their velocities, which are momentum-matched with the higher-kinetic-energy Cl atom photofragments, shows that the vinoxy radicals dissociatively photoionize to give signal at m/z = 15 and 29. We calibrated the partial photoionization cross section of vinoxy to CH3+ relative to the bandwidth-averaged photoionization cross section of the Cl atom at 13.68 eV to put the partial photoionization cross sections on an absolute scale. The resulting bandwidth-averaged partial cross sections are 0.63 and 1.3 Mb at 10.5 and 11.44 eV, respectively. These values are consistent with the upper limit to the cross section estimated from a study by Savee et al. on the O(3P) + propene bimolecular reaction. We note that the uncertainty in these values is primarily dependent on the signal attributed to C-Cl primary photofission in the m/z = 35 (Cl+) time-of-flight data. While the value is a rough estimate, the bandwidth-averaged partial photoionization cross section of vinoxy to HCO+ calculated from the signal at m/z = 29 at 11.53 eV is approximately half that of vinoxy to CH3+. We also present critical points on the potential energy surface of the vinoxy cation calculated at the G4//B3LYP/6-311++G(3df,2p) level of theory to support the observation of dissociative ionization of vinoxy to both CH3+ and HCO+.
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Affiliation(s)
- Jonathan D Adams
- The James Franck Institute and Department of Chemistry, The University of Chicago , Chicago, Illinois 60637, United States
| | - Preston G Scrape
- The James Franck Institute and Department of Chemistry, The University of Chicago , Chicago, Illinois 60637, United States
| | - Shih-Huang Lee
- National Synchrotron Radiation Research Center , Hsinchu 30076, Taiwan, Republic of China
| | - Laurie J Butler
- The James Franck Institute and Department of Chemistry, The University of Chicago , Chicago, Illinois 60637, United States
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Wilhelm MJ, McNavage W, Smith JM, Dai HL. The lowest quartet-state of the ketenyl (HCCO) radical: Collision-induced intersystem crossing and the ν2 vibrational mode. Chem Phys 2013. [DOI: 10.1016/j.chemphys.2013.04.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Wilhelm MJ, Nikow M, Smith JM, Dai HL. Collisional Energy Transfer from Highly Vibrationally Excited Radicals Is Very Efficient. J Phys Chem Lett 2013; 4:23-29. [PMID: 26291206 DOI: 10.1021/jz301761e] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Although highly vibrationally excited (HVE) radicals are ubiquitous in natural environments, the effect of collisional energy transfer (ET) on their reactivity has yet to be fully characterized. We have used time-resolved IR emission spectroscopy to characterize the vibrational-to-translational quenching of a small HVE radical, ketenyl (HCCO), by inert gases. Photolysis of ethyl ethynyl ether at 193 nm provides HVE HCCO in the X̃(2)A″ electronic ground-state, with a nascent internal energy of 2.2 ± 0.6 eV. IR emission is monitored as an indicator of vibrational energy, and spectral modeling allows direct determination of the average energy lost per collision as a function of the internal energy. Collisional deactivation of HVE HCCO is shown to be minimally an order of magnitude more efficient than closed-shell molecules of comparable size. Schwartz-Slawsky-Herzfeld-Tanczos (SSHT) theory, modified for HVE molecules, suggests that this ET enhancement is due to a strong attractive intermolecular interaction.
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Affiliation(s)
- Michael J Wilhelm
- †Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Matthew Nikow
- †Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Jonathan M Smith
- ‡Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Hai-Lung Dai
- ‡Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
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Du L, Carl SA. Absolute Rate Coefficient and Mechanism of Gas Phase Reaction of Ketenyl Radical and SO2. J Phys Chem A 2012; 116:10074-81. [DOI: 10.1021/jp308457m] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lin Du
- Department of Chemistry, Katholieke Universiteit Leuven, B-3001 Leuven, Belgium
| | - Shaun A. Carl
- Department of Chemistry, Katholieke Universiteit Leuven, B-3001 Leuven, Belgium
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Simmonett AC, Stibrich NJ, Papas BN, Schaefer HF, Allen WD. Barrier To Linearity and Anharmonic Force Field of the Ketenyl Radical. J Phys Chem A 2009; 113:11643-50. [DOI: 10.1021/jp9024365] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Andrew C. Simmonett
- Center for Computational Quantum Chemistry and Department of Chemistry, University of Georgia, Athens, Georgia 30602
| | - Nathan J. Stibrich
- Center for Computational Quantum Chemistry and Department of Chemistry, University of Georgia, Athens, Georgia 30602
| | - Brian N. Papas
- Center for Computational Quantum Chemistry and Department of Chemistry, University of Georgia, Athens, Georgia 30602
| | - Henry F. Schaefer
- Center for Computational Quantum Chemistry and Department of Chemistry, University of Georgia, Athens, Georgia 30602
| | - Wesley D. Allen
- Center for Computational Quantum Chemistry and Department of Chemistry, University of Georgia, Athens, Georgia 30602
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Signal-to-noise enhancement in time-resolved IR emission spectra through two-dimensional correlation analysis. J Mol Struct 2008. [DOI: 10.1016/j.molstruc.2008.01.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Wilhelm MJ, McNavage W, Groller R, Dai HL. The ν1 CH stretching mode of the ketenyl (HCCO) radical. J Chem Phys 2008; 128:064313. [DOI: 10.1063/1.2829400] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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FitzPatrick BL, Maienschein-Cline M, Butler LJ, Lee SH, Lin JJ. Determining the Partial Photoionization Cross-Sections of Ethyl Radicals. J Phys Chem A 2007; 111:12417-22. [PMID: 17760439 DOI: 10.1021/jp073828h] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Using a crossed laser-molecular beam scattering apparatus, these experiments photodissociate ethyl chloride at 193 nm and detect the Cl and ethyl products, resolved by their center-of-mass recoil velocities, with vacuum ultraviolet photoionization. The data determine the relative partial cross-sections for the photoionization of ethyl radicals to form C2H5+, C2H4+, and C2H3+ at 12.1 and 13.8 eV. The data also determine the internal energy distribution of the ethyl radical prior to photoionization, so we can assess the internal energy dependence of the photoionization cross-sections. The results show that the C2H4++H and C2H3++H2 dissociative photoionization cross-sections strongly depend on the photoionization energy. Calibrating the ethyl radical partial photoionization cross-sections relative to the bandwidth-averaged photoionization cross-section of Cl atoms near 13.8 eV allows us to use these data in conjunction with literature estimates of the Cl atom photoionization cross-sections to put the present bandwidth-averaged cross-sections on an absolute scale. The resulting bandwidth-averaged cross-section for the photoionization of ethyl radicals to C2H5+ near 13.8 eV is 8+/-2 Mb. Comparison of our 12.1 eV data with high-resolution ethyl radical photoionization spectra allows us to roughly put the high-resolution spectrum on the same absolute scale. Thus, one obtains the photoionization cross-section of ethyl radicals to C2H5+ from threshold to 12.1 eV. The data show that the onset of the C2H4++H dissociative photoionization channel is above 12.1 eV; this result offers a simple way to determine whether the signal observed in photoionization experiments on complex mixtures is due to ethyl radicals. We discuss an application of the results for resolving the product branching in the O+allyl bimolecular reaction.
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Affiliation(s)
- B L FitzPatrick
- The James Franck Institute and Department of Chemistry, University of Chicago, Chicago, Illinois 60637, USA
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Carl SA, Vereecken L, Peeters J. Kinetic parameters for gas-phase reactions: experimental and theoretical challenges. Phys Chem Chem Phys 2007; 9:4071-84. [PMID: 17687459 DOI: 10.1039/b705505f] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This article aims to illustrate the added value provided to experimental kinetics investigations by complementary theoretical kinetics studies, using as examples (i) reactions of two major hydrocarbon flame radicals, HCCO and C(2)H, and (ii) reactions of several oxygenated organic compounds with hydroxyl radicals of interest to atmospheric chemistry. The first part, on HCCO and C(2)H kinetics, does not attempt to give an extensive literature review, but rather addresses some major experimental techniques, mainly specific ones, that have allowed a great part of the available reactivity databases on these two species to be established. For several key reactions, it is shown how potential energy surfaces and statistical rate predictions based thereon have provided insight into the molecular mechanisms and have allowed estimates of product distributions as well as reliable extrapolations of experimental rate coefficients and branching ratios to higher temperatures. The second part addresses current issues in atmospheric chemistry relating mainly to hydroxyl radical reactions with oxygenated organics, and focuses on the experimental characterization of the often unusual temperature dependence of their rate coefficients and on the theoretical rationalization thereof, through the formation of hydrogen-bonded pre-reactive complexes and resulting tunnelling-enhanced H-abstraction. Finally, the development of general structure-activity relationships for OH reactions with organics, H-abstractions as well as OH-additions for unsaturated compounds, is briefly discussed.
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Affiliation(s)
- S A Carl
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium.
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Piechowska-Strumik K, Bacchus-Montabonel MC, Tergiman YS, Sienkiewicz JE. An ab initio study of the excited states of the vinoxy radical. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2006.05.049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Fockenberg C. Product Study of the Photolysis of Ketene and Ethyl Ethynyl Ether at 193.3 nm. J Phys Chem A 2005; 109:7140-50. [PMID: 16834078 DOI: 10.1021/jp044092g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The product distributions of the excimer laser photolysis of ketene (CH2CO) and ethyl ethynyl ether (C2H5OCCH) at lambda = 193.3 nm (ArF) were studied using a time-of-flight mass spectrometer (TOFMS) as an analytical tool. Ketene was photolyzed in bath gases consisting of mixtures of He and H2/D2 at various mixing ratios at constant total pressures of 4 Torr and temperature of about 300 K. Singlet methylene (1CH2) produced in the photolysis of ketene was almost instantaneously converted either to triplet methylene (3CH2) or to methyl radicals in collisions with He and H2 or D2. By extrapolating the methyl and methylene signals to zero time after photolysis, initial concentrations of these radicals were obtained. Analyzing the initial 3CH2 and CH3 concentrations as functions of hydrogen-to-helium ratios as well as simulating the observed traces of reactant and product species resulted in 1CH2 + CO (66 +/- 8)%, as the main product channel of the ketene photolysis with smaller contributions from HCCO + H (17 +/- 7)% and 3CH2 + CO (6 +/- 9)%. Hydrogen atoms, acetylene, ethylene, ethyl, and ketenyl radicals, and small amounts of ketene were observed as primary products of the ethyl ethynyl ether photolysis. Quantification of C2H2, C2H4, C2H5, and CH2CO product leads to a HCCO yield of (91 +/- 14)%.
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Affiliation(s)
- Christopher Fockenberg
- Chemistry Department 555A, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973-5000, USA.
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Abstract
The kinetics of the HCCO + NO2 reaction were investigated using a laser photolysis/infrared diode laser absorption technique. Ethyl ethynyl ether (C2H5OCCH) was used as the HCCO radical precursor. Transient infrared detection of the HCCO radical was used to determine a total rate constant fit to the following expression: k1= (2.43 +/- 0.26) x 10(-11) exp[(171.1 +/- 36.9)/T] cm3 molecule(-1) s(-1) over the temperature range of 298-423 K. Transient infrared detection of CO, CO2, and HCNO products was used to determine the following branching ratios at 298 K: phi(HCO + NO + CO) = 0.60 +/- 0.05 and phi(HCNO + CO2) = 0.40 +/- 0.05.
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Affiliation(s)
- Justin P Meyer
- Department of Chemistry and Molecular Biology, North Dakota State University, Fargo, North Dakota 58105, USA
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Chikan V, Leone SR. Vibrational Distributions of the CO(v) Products of the C2H2+ O(3P) and HCCO + O(3P) Reactions Studied by FTIR Emission. J Phys Chem A 2005; 109:2525-33. [PMID: 16833554 DOI: 10.1021/jp040585+] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The C2H2 + O(3P) and HCCO + O(3P) reactions are investigated using Fourier transform infrared (FTIR) emission spectroscopy. The O(3P) radicals are produced by 193 nm photolysis of an SO2 precursor or microwave discharge in O2. The HCCO radical is either formed in the first step of the C2H2 + O(3P) reaction or by 193 nm photodissociation of ethyl ethynyl ether. Vibrationally excited CO and CO2 products are observed. The microwave discharge experiment [C2H2 + O(3P)] shows a bimodal distribution of the CO(v) product, which is due to the sequential C2H2 + O(3P) and HCCO + O(3P) reactions. The vibrational distribution of CO(v) from the HCCO + O(3P) reaction also shows its own bimodal shape. The vibrational distribution of CO(v) from C2H2 + O(3P) can be characterized by a Boltzmann plot with a vibrational temperature of approximately 2400 +/- 100 K, in agreement with previous results. The CO distribution from the HCCO + O(3P) reaction, when studied under conditions to minimize other processes, shows very little contamination from other reactions, and the distribution can be characterized by a linear combination of Boltzmann plots with two vibrational temperatures: 2320 +/- 40 and 10 300 +/- 600 K. From the experimental results and previous theoretical work, the bimodal CO(v) distribution for the HCCO + O(3P) reaction suggests a sequential dissociation process of the HC(O)CO++ --> CO + HCO; HCO --> H + CO.
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Affiliation(s)
- Viktor Chikan
- Department of Chemistry and Physics and Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720-1460, USA
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Abstract
The product branching ratio of the HCCO + NO reaction was investigated using the laser photolysis/infrared absorption technique. Ethyl ethynyl ether (C(2)H(5)OCCH) was used as the HCCO radical precursor. Transient infrared detection of CO, CO(2), and HCNO products was used to determine the following branching ratios at 296 K: phi(CO+HCNO) = 0.78 +/- 0.04 and phi(CO(2)+HCN) = 0.22 +/- 0.04. These values are in good agreement with some recent ab initio calculations.
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Affiliation(s)
- Justin P Meyer
- Department of Chemistry and Molecular Biology, North Dakota State University, Fargo, North Dakota 58105, USA
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Zou P, Osborn DL. On the mechanism of the HCCO + O2reaction: Probing multiple pathways to a single product channel. Phys Chem Chem Phys 2004. [DOI: 10.1039/b400183d] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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