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Dodson LG, Shen L, Savee JD, Eddingsaas NC, Welz O, Taatjes CA, Osborn DL, Sander SP, Okumura M. VUV photoionization cross sections of HO2, H2O2, and H2CO. J Phys Chem A 2015; 119:1279-91. [PMID: 25621533 DOI: 10.1021/jp508942a] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The absolute vacuum ultraviolet (VUV) photoionization spectra of the hydroperoxyl radical (HO2), hydrogen peroxide (H2O2), and formaldehyde (H2CO) have been measured from their first ionization thresholds to 12.008 eV. HO2, H2O2, and H2CO were generated from the oxidation of methanol initiated by pulsed-laser-photolysis of Cl2 in a low-pressure slow flow reactor. Reactants, intermediates, and products were detected by time-resolved multiplexed synchrotron photoionization mass spectrometry. Absolute concentrations were obtained from the time-dependent photoion signals by modeling the kinetics of the methanol oxidation chemistry. Photoionization cross sections were determined at several photon energies relative to the cross section of methanol, which was in turn determined relative to that of propene. These measurements were used to place relative photoionization spectra of HO2, H2O2, and H2CO on an absolute scale, resulting in absolute photoionization spectra.
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Affiliation(s)
- Leah G Dodson
- Division of Chemistry and Chemical Engineering and §NASA Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California 91125, United States
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2
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Xu H, Pratt ST. Photoionization Cross Section of the Propargyl Radical and Some General Ideas for Estimating Radical Cross Sections. J Phys Chem A 2012. [DOI: 10.1021/jp309874q] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hong Xu
- Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - S. T. Pratt
- Argonne National Laboratory, Argonne, Illinois 60439, United States
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3
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Daniel Freeman C, Grubb MP, Lane IC, North SW. Vibrational state-selected photodissociation of ClO+. Chem Phys 2012. [DOI: 10.1016/j.chemphys.2012.09.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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4
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Savee JD, Soorkia S, Welz O, Selby TM, Taatjes CA, Osborn DL. Absolute photoionization cross-section of the propargyl radical. J Chem Phys 2012; 136:134307. [PMID: 22482552 DOI: 10.1063/1.3698282] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Using synchrotron-generated vacuum-ultraviolet radiation and multiplexed time-resolved photoionization mass spectrometry we have measured the absolute photoionization cross-section for the propargyl (C(3)H(3)) radical, σ(propargyl) (ion)(E), relative to the known absolute cross-section of the methyl (CH(3)) radical. We generated a stoichiometric 1:1 ratio of C(3)H(3):CH(3) from 193 nm photolysis of two different C(4)H(6) isomers (1-butyne and 1,3-butadiene). Photolysis of 1-butyne yielded values of σ(propargyl)(ion)(10.213 eV)=(26.1±4.2) Mb and σ(propargyl)(ion)(10.413 eV)=(23.4±3.2) Mb, whereas photolysis of 1,3-butadiene yielded values of σ(propargyl)(ion)(10.213 eV)=(23.6±3.6) Mb and σ(propargyl)(ion)(10.413 eV)=(25.1±3.5) Mb. These measurements place our relative photoionization cross-section spectrum for propargyl on an absolute scale between 8.6 and 10.5 eV. The cross-section derived from our results is approximately a factor of three larger than previous determinations.
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Affiliation(s)
- John D Savee
- Sandia National Laboratories, Combustion Research Facility, Livermore, California 94551, USA
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Xu H, Jacovella U, Ruscic B, Pratt ST, Lucchese RR. Near-threshold shape resonance in the photoionization of 2-butyne. J Chem Phys 2012; 136:154303. [DOI: 10.1063/1.3701762] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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6
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Shubert VA, Pratt ST. Photodissociation of Acetaldehyde and the Absolute Photoionization Cross Section of HCO. J Phys Chem A 2010; 114:11238-43. [DOI: 10.1021/jp102992b] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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7
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Loison JC. Absolute Photoionization Cross Section of the Methyl Radical. J Phys Chem A 2010; 114:6515-20. [DOI: 10.1021/jp1024312] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jean-Christophe Loison
- Institut des Sciences Moléculaires, CNRS UMR 5255, Université Bordeaux I, 33405 Talence Cedex, France
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Gans B, Mendes LAV, Boyé-Péronne S, Douin S, Garcia G, Soldi-Lose H, de Miranda BKC, Alcaraz C, Carrasco N, Pernot P, Gauyacq D. Determination of the Absolute Photoionization Cross Sections of CH3 and I Produced from a Pyrolysis Source, by Combined Synchrotron and Vacuum Ultraviolet Laser Studies. J Phys Chem A 2009; 114:3237-46. [DOI: 10.1021/jp909414d] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Bérenger Gans
- Laboratoire de Photophysique Moléculaire, CNRS UPR 3361, Univ. Paris-Sud 11, Bât. 210, F-91405 Orsay Cédex, France
| | - Luiz A. Vieira Mendes
- Laboratoire de Photophysique Moléculaire, CNRS UPR 3361, Univ. Paris-Sud 11, Bât. 210, F-91405 Orsay Cédex, France
| | - Séverine Boyé-Péronne
- Laboratoire de Photophysique Moléculaire, CNRS UPR 3361, Univ. Paris-Sud 11, Bât. 210, F-91405 Orsay Cédex, France
| | - Stéphane Douin
- Laboratoire de Photophysique Moléculaire, CNRS UPR 3361, Univ. Paris-Sud 11, Bât. 210, F-91405 Orsay Cédex, France
| | - Gustavo Garcia
- Laboratoire de Photophysique Moléculaire, CNRS UPR 3361, Univ. Paris-Sud 11, Bât. 210, F-91405 Orsay Cédex, France
| | - Héloïse Soldi-Lose
- Laboratoire de Photophysique Moléculaire, CNRS UPR 3361, Univ. Paris-Sud 11, Bât. 210, F-91405 Orsay Cédex, France
| | - Barbara K. Cunha de Miranda
- Laboratoire de Photophysique Moléculaire, CNRS UPR 3361, Univ. Paris-Sud 11, Bât. 210, F-91405 Orsay Cédex, France
| | - Christian Alcaraz
- Laboratoire de Photophysique Moléculaire, CNRS UPR 3361, Univ. Paris-Sud 11, Bât. 210, F-91405 Orsay Cédex, France
| | - Nathalie Carrasco
- Laboratoire de Photophysique Moléculaire, CNRS UPR 3361, Univ. Paris-Sud 11, Bât. 210, F-91405 Orsay Cédex, France
| | - Pascal Pernot
- Laboratoire de Photophysique Moléculaire, CNRS UPR 3361, Univ. Paris-Sud 11, Bât. 210, F-91405 Orsay Cédex, France
| | - Dolores Gauyacq
- Laboratoire de Photophysique Moléculaire, CNRS UPR 3361, Univ. Paris-Sud 11, Bât. 210, F-91405 Orsay Cédex, France
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Dooley KS, Grubb MP, Geidosch J, van Beek MA, Groenenboom GC, North SW. Correlated fine structure branching ratios arising from state-selected predissociation of ClO (A2Π3/2). Phys Chem Chem Phys 2009; 11:4770-6. [DOI: 10.1039/b823004h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Taatjes CA, Osborn DL, Selby TM, Meloni G, Fan H, Pratt ST. Absolute photoionization cross-section of the methyl radical. J Phys Chem A 2008; 112:9336-43. [PMID: 18572896 DOI: 10.1021/jp8022937] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The absolute photoionization cross-section of the methyl radical has been measured using two completely independent methods. The CH3 photoionization cross-section was determined relative to that of acetone and methyl vinyl ketone at photon energies of 10.2 and 11.0 eV by using a pulsed laser-photolysis/time-resolved synchrotron photoionization mass spectrometry method. The time-resolved depletion of the acetone or methyl vinyl ketone precursor and the production of methyl radicals following 193 nm photolysis are monitored simultaneously by using time-resolved synchrotron photoionization mass spectrometry. Comparison of the initial methyl signal with the decrease in precursor signal, in combination with previously measured absolute photoionization cross-sections of the precursors, yields the absolute photoionization cross-section of the methyl radical; sigma(CH3)(10.2 eV) = (5.7 +/- 0.9) x 10(-18) cm(2) and sigma(CH3)(11.0 eV) = (6.0 +/- 2.0) x 10(-18) cm(2). The photoionization cross-section for vinyl radical determined by photolysis of methyl vinyl ketone is in good agreement with previous measurements. The methyl radical photoionization cross-section was also independently measured relative to that of the iodine atom by comparison of ionization signals from CH3 and I fragments following 266 nm photolysis of methyl iodide in a molecular-beam ion-imaging apparatus. These measurements gave a cross-section of (5.4 +/- 2.0) x 10(-18) cm(2) at 10.460 eV, (5.5 +/- 2.0) x 10(-18) cm(2) at 10.466 eV, and (4.9 +/- 2.0) x 10(-18) cm(2) at 10.471 eV. The measurements allow relative photoionization efficiency spectra of methyl radical to be placed on an absolute scale and will facilitate quantitative measurements of methyl concentrations by photoionization mass spectrometry.
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Affiliation(s)
- Craig A Taatjes
- Combustion Research Facility, Mail Stop 9055, Sandia National Laboratories, Livermore, California 94551-0969, USA.
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Flesch R, Wirsing A, Barthel M, Plenge J, Rühl E. Inner-valence photoionization of O(D1): Experimental evidence for the 2s22p4(D1)→2s12p5(P1) transition. J Chem Phys 2008; 128:074307. [DOI: 10.1063/1.2830232] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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McCunn LR, FitzPatrick BL, Krisch MJ, Butler LJ, Liang CW, Lin JJ. Unimolecular dissociation of the propargyl radical intermediate of the CH+C2H2 and C+C2H3 reactions. J Chem Phys 2006; 125:133306. [PMID: 17029459 DOI: 10.1063/1.2353821] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
This paper examines the unimolecular dissociation of propargyl (HCCCH2) radicals over a range of internal energies to probe the CH+HCCH and C+C2H3 bimolecular reactions from the radical intermediate to products. The propargyl radical was produced by 157 nm photolysis of propargyl chloride in crossed laser-molecular beam scattering experiments. The H-loss and H2 elimination channels of the nascent propargyl radicals were observed. Detection of stable propargyl radicals gave an experimental determination of 71.5 (+5-10) kcal/mol as the lowest barrier to dissociation of the radical. This barrier is significantly lower than predictions for the lowest barrier to the radical's dissociation and also lower than calculated overall reaction enthalpies. Products from both H2+HCCC and H+C3H2 channels were detected at energies lower than what has been theoretically predicted. An HCl elimination channel and a minor C-H fission channel were also observed in the photolysis of propargyl chloride.
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Affiliation(s)
- Laura R McCunn
- The James Franck Institute and Department of Chemistry, University of Chicago, Chicago, Illinois 60637, USA
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Kim H, Dooley KS, Groenenboom GC, North SW. Vibrational state-dependent predissociation dynamics of ClO (A2Π3/2): Insight from correlated fine structure branching ratios. Phys Chem Chem Phys 2006; 8:2964-71. [PMID: 16880909 DOI: 10.1039/b603353a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have studied the v'-dependent predissociation dynamics of the ClO A (2)Pi(3/2) state using velocity-map ion-imaging. Experimental final correlated state branching ratios, i.e. Cl((2)P(J=3/2,1/2)) + O((3)P(J=2,1,0)) channels, have been measured for v' = 6-11. We find that the branching ratios are highly variable and depend strongly on v', providing a window into the v'-dependent predissociation mechanism. A comparison of the experimental results with the recent model of Lane et al. (I. C. Lane, W. H. Howie and A. J. Orr-Ewing, Phys. Chem. Chem. Phys., 1999, 1, 3087) in both the diabatic and adiabatic limits suggests that the dynamics are closer to the diabatic limit. The overall Cl((2)P(J)) branching ratios are in good agreement with the diabatic model results. There are significant differences, however, between theory and experiment at the correlated state level, demonstrating the sensitivity of correlated measurements to the role of the exit channel coupling in the predissociation dynamics. The results highlight the need for more sophisticated quantum dynamical calculations to describe the correlated fine structure branching ratios in this system.
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Affiliation(s)
- Hahkjoon Kim
- Department of Chemistry, Texas A and University, P. O. Box 30012, College Station, Texas 77842, USA
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Sveum NE, Goncher SJ, Neumark DM. Determination of absolute photoionization cross sections of the phenyl radical. Phys Chem Chem Phys 2006; 8:592-8. [PMID: 16482301 DOI: 10.1039/b513960k] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Photoionization cross sections of the phenyl radical to form the phenyl cation were measured using tunable vacuum ultraviolet synchrotron radiation coupled with photofragment translational spectroscopy. The phenyl radical was produced via 193- or 248-nm dissociation of chlorobenzene. At 10.0 eV, the photoionization cross sections for the phenyl radical averaged over product channels were found to be 13.4 +/- 2.0 and 13.2 +/- 2.0 Mb, respectively, with very little effect seen from the range of internal excitation produced at the two photolysis wavelengths. Using the photoionization cross section values for each channel, photoionization efficiency curves for the phenyl radical were placed on an absolute scale from 7.8 to 10.8 eV.
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Affiliation(s)
- Niels E Sveum
- Department of Chemistry, University of California, Berkeley, 94720, USA
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Kim H, Park J, Niday TC, North SW. The UV photodissociation dynamics of ClO radical using velocity map ion imaging. J Chem Phys 2005; 123:174303. [PMID: 16375524 DOI: 10.1063/1.2083487] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have studied the wavelength-dependent photodissociation dynamics of jet-cooled ClO radical from 235 to 291 nm using velocity map ion imaging. We find that Cl(2P(3/2))+O(1D(2)) is the dominant channel above the O(1D(2)) threshold with minor contributions from the Cl(2P(J))+O(3P(J)) and Cl(2P(1/2))+O(1D(2)) channels. We have measured the photofragment angular distributions for each dissociation channel and find that the A 2pi state reached via a parallel transition carries most of the oscillator strength above the O(1D(2)) threshold. The formation of O(3P(J)) fragments with positive anisotropy is evidence of curve crossing from the A 2pi state to one of several dissociative states. The curve crossing probability increases with wavelength in good agreement with previous theoretical calculations. We have directly determined the O(1D(2)) threshold to be 38,050+/-20 cm(-1) by measuring O(1D(2)) quantum yield in the wavelength range of 260-270 nm. We also report on the predissociation dynamics of ClO below the O(1D(2)) threshold. We find that the branching ratio of Cl(2P(3/2))/Cl(2P(1/2)) is 1.5+/-0.1 at both 266 and 291 nm. The rotational depolarization of the anisotropy parameters of the Cl(2P(3/2)) fragments provides predissociation lifetimes of 1.5+/-0.2 ps for the 9-0 band and 1.0+/-0.4 ps for the 8-0 band, in reasonable agreement with previous spectroscopic and theoretical studies.
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Affiliation(s)
- Hahkjoon Kim
- Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, Texas 77842, USA
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Abstract
Vibrationally hot CH(3) and CF(3) were produced by the 266 nm photodissociation of CH(3)I and CF(3)I, respectively, and probed by single-photon ionization at 118 nm. Comparison of the ion images of the CH(3) and CF(3) fragments with those of the complementary I atoms, and with previous measurements of the product branching fractions, allowed the determination of the relative photoion yields as a function of the vibrational energy of the molecular radical. Some general ideas about the internal-energy dependence of photoionization cross sections are also discussed.
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Affiliation(s)
- F Aguirre
- Argonne National Laboratory, Argonne, Illinois 60439, USA
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Plenge J, Flesch R, Kühl S, Vogel B, Müller R, Stroh F, Rühl E. Ultraviolet Photolysis of the ClO Dimer. J Phys Chem A 2004. [DOI: 10.1021/jp049690+] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Robinson JC, Sveum NE, Neumark DM. Determination of absolute photoionization cross sections for isomers of C3H5: allyl and 2-propenyl radicals. Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2003.11.075] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Robinson JC, Sveum NE, Neumark DM. Determination of absolute photoionization cross sections for vinyl and propargyl radicals. J Chem Phys 2003. [DOI: 10.1063/1.1606440] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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