1
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Chen A, Miao T. Photoionization of the Propargyl Radical Using the R-Matrix Method. J Phys Chem A 2024; 128:1226-1232. [PMID: 38330917 DOI: 10.1021/acs.jpca.3c07259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
The absolute photoionization cross section of the propargyl radical measured by Savee et al. [J. Chem. Phys. 2012, 136, 134307] is about 2-3 times larger than the experimental result from Robinson et al. [J. Chem. Phys. 2003, 119, 5311]. Meanwhile, there is a significant discrepancy in the shapes of the propargyl photoionization spectra between these two measurements and the result measured by Zhang et al. [J. Chem. Phys. 2006, 124, 074302]. To estimate the accuracy of the various results, we carried out comprehensive calculations with the multichannel R-matrix method, which uses multiconfigurational wave functions to generate accurate initial and final states. Three scattering models including static-exchange, correlated 1 state, and 80 state close-coupling (CC) approximations are employed to reveal the dynamic interaction. The autoionization peaks near the ionization threshold are predicted for the first time. Two resonances are detected with the photon energy around 41.4 and 49.6 eV in the 80 state CC model. We checked the sensitivity of the results to change descriptions of the active spaces, the different partial waves, and the R-matrix radii in the theoretical model. Our best results are compared with the experimental measurements, and discussions are provided. The cross sections and asymmetry parameters for the valence orbitals are reported for photon energies from ionization thresholds of 70 eV.
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Affiliation(s)
- Aimin Chen
- School of Chemistry and Material Engineering, Xinxiang University, Xinxiang 453003, P. R. China
| | - Tongjun Miao
- School of Physics and Electronic Engineering, Xinxiang University, Xinxiang 453003, P. R. China
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2
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Zhao H, Pan Y, Lau KC. Ferrocene/ferrocenium, cobaltocene/cobaltocenium and nickelocene/nickelocenium: from gas phase ionization energy to one-electron reduction potential in solvated medium. Phys Chem Chem Phys 2023. [PMID: 37325896 DOI: 10.1039/d3cp01904g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
We propose a theoretical procedure for accurate determination of reduction potentials for three metallocene couples, Cp2M+/Cp2M, where M = Fe, Co and Ni. This procedure first computes the gas phase ionization energy (IE) using the explicitly correlated CCSD(T)-F12 method and includes the zero-point energy correction, core-valence electronic correlation, and relativistic and spin-orbit coupling effects. By means of Born-Haber thermochemical cycle, the one-electron reduction potential is obtained as the sum of the gas phase IE and the corresponding Gibbs free energies of solvation (ΔGsolv) for both the neutral and cationic species. Among the three solvent models (PCM, SMD and uESE) investigated here, it turns out that only the SMD model (computed at the DFT level) gives the best estimation of the value for "ΔGsolv(cation) - ΔGsolv(neutral)" and thus, combining with the accurate IE values, the theoretical protocol is capable of yielding reliable values (in V) for , and . These predictions compare favorably with the available experimental data (in V): , , and . We show that our theoretical procedure is reliable for accurate reduction potential predictions of Cp2Fe+/Cp2Fe, Cp2Co+/Cp2Co and Cp2Ni+/Cp2Ni redox couples in aqueous and non-aqueous media; the maximum absolute deviation is as small as ≈120 mV, which outperforms those of the existing theoretical methods.
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Affiliation(s)
- Hongyan Zhao
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong.
| | - Yi Pan
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong.
| | - Kai-Chung Lau
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong.
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3
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Blitz MA, Pilling MJ, Robertson SH, Seakins PW, Speak TH. Global Master Equation Analysis of Rate Data for the Reaction C 2H 4 + H ⇄ C 2H 5: Δ fH0⊖C 2H 5. J Phys Chem A 2021; 125:9548-9565. [PMID: 34704447 DOI: 10.1021/acs.jpca.1c05911] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
While forward and reverse rate constants are frequently used to determine enthalpies of reaction and formation, this process is more difficult for pressure-dependent association/dissociation reactions, especially since the forward and reverse reactions are usually studied at very different temperatures. The problems can be overcome by using a data-fitting procedure based on a master equation model. This approach has been applied to existing experimental pressure-dependent forward and reverse rate coefficients for the reaction C2H4 + H ⇄ C2H5 (k1, k-1) using the MESMER code to determine ΔfH0⊖C2H5 from the enthalpy of the reaction. New measurements of k1, k-1 were included in analysis. They are based on laser flash photolysis with direct observation of H atom time profiles by vacuum ultraviolet laser-induced fluorescence under conditions where the approach to equilibrium could be observed. Measurements were made over the temperature range 798-828 K and with [He] from 2.33 to 7.21 × 1018 molecule cm-3. These data were then combined with a wide range of existing experimental data with helium as the bath gas (112 measurements of k1 and k-1, covering the temperature range 285-1094 K, and [He] = 7.1 × 1015-1.9 × 1019 molecule cm-3) and fitted using the master equation solver MESMER. The required vibrational frequencies and rotational constants of the system were obtained from ab initio calculations, and the activation threshold for association (ΔEthresh), enthalpy of reaction (ΔrH0⊖), imaginary frequency (υimag), and helium energy-transfer parameters (⟨ΔE⟩d,298(T/298)n) were optimized. The resulting parameters (errors are 2σ) are ΔEthresh = 11.43 ± 0.34 kJ mol-1, ΔrH0⊖ = -145.34 ± 0.60 kJ mol-1, υimag = 730 ± 130 cm-1, ⟨ΔE⟩d,298 = 54.2 ± 7.6 cm-1, and n = 1.17 ± 0.12. A value of ΔfH298.15⊖(C2H5) = 120.49 ± 0.57 kJ mol-1 is obtained by combining ΔrH0⊖ with standard enthalpies of formation for H and C2H4 and making the appropriate temperature corrections. The dependence of these parameters on how the internal rotor and CH2 inversion modes are treated has been explored. The experimental data for other bath gases have been analyzed, and data sets compatible with the potential energy surface parameters determined above have been identified. The parameters are virtually identical but with slightly smaller error limits. Parameterization of k1, k-1 using the Troe formalization has been used to investigate competition between ethyl decomposition and reaction with oxygen under combustion conditions.
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Affiliation(s)
- Mark A Blitz
- School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K.,National Centre for Atmospheric Science (NCAS), University of Leeds, Leeds LS2 9JT, U.K
| | | | | | - Paul W Seakins
- School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K
| | - Thomas H Speak
- School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K
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4
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Sugisaki K, Toyota K, Sato K, Shiomi D, Takui T. Quantum Algorithm for the Direct Calculations of Vertical Ionization Energies. J Phys Chem Lett 2021; 12:2880-2885. [PMID: 33724039 DOI: 10.1021/acs.jpclett.1c00283] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Recently, a quantum algorithm that is capable of directly calculating the energy gap between two electronic states having different spin quantum numbers without inspecting the total energy of the individual electronic states was proposed. This quantum algorithm guarantees an exponential speedup, like quantum phase estimation (QPE)-based full-CI, with much lower costs. In this work, we propose a modified quantum circuit for the direct calculations of spin state energy gaps to reduce the number of qubits and quantum gates, extending the quantum algorithm to the direct calculation of vertical ionization energies. Numerical quantum circuit simulations for the ionization of light atoms (He, Li, Be, B, C, and N) and small molecules (HF, BF, CF, CO, O2, NO, CN, F2, H2O, and NH3) revealed that the proposed quantum algorithm affords the vertical ionization energies within 0.1 eV of precision.
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Affiliation(s)
- Kenji Sugisaki
- Department of Chemistry and Molecular Materials Science, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan
- JST PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
- Centre for Quantum Engineering, Research and Education (CQuERE), TCG Centres for Research and Education in Science and Technology (TCG CREST), 16th Floor, Omega, BIPL Building, Blocks EP & GP, Sector V, Salt Lake, Kolkata 700091, India
| | - Kazuo Toyota
- Department of Chemistry and Molecular Materials Science, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Kazunobu Sato
- Department of Chemistry and Molecular Materials Science, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Daisuke Shiomi
- Department of Chemistry and Molecular Materials Science, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Takeji Takui
- Department of Chemistry and Molecular Materials Science, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan
- Research Support Department/University Research Administrator Center, University Administration Division, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan
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5
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Reusch E, Holzmeier F, Gerlach M, Fischer I, Hemberger P. Decomposition of Picolyl Radicals at High Temperature: A Mass Selective Threshold Photoelectron Spectroscopy Study. Chemistry 2019; 25:16652-16659. [PMID: 31637775 PMCID: PMC6972682 DOI: 10.1002/chem.201903937] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 10/16/2019] [Indexed: 01/24/2023]
Abstract
The reaction products of the picolyl radicals at high temperature were characterized by mass-selective threshold photoelectron spectroscopy in the gas phase. Aminomethylpyridines were pyrolyzed to initially produce picolyl radicals (m/z=92). At higher temperatures further thermal reaction products are generated in the pyrolysis reactor. All compounds were identified by mass-selected threshold photoelectron spectroscopy and several hitherto unexplored reactive molecules were characterized. The mechanism for several dissociation pathways was outlined in computations. The spectrum of m/z=91, resulting from hydrogen loss of picolyl, shows four isomers, two ethynyl pyrroles with adiabatic ionization energies (IEad ) of 7.99 eV (2-ethynyl-1H-pyrrole) and 8.12 eV (3-ethynyl-1H-pyrrole), and two cyclopentadiene carbonitriles with IE's of 9.14 eV (cyclopenta-1,3-diene-1-carbonitrile) and 9.25 eV (cyclopenta-1,4-diene-1-carbonitrile). A second consecutive hydrogen loss forms the cyanocyclopentadienyl radical with IE's of 9.07 eV (T0 ) and 9.21 eV (S1 ). This compound dissociates further to acetylene and the cyanopropynyl radical (IE=9.35 eV). Furthermore, the cyclopentadienyl radical, penta-1,3-diyne, cyclopentadiene and propargyl were identified in the spectra. Computations indicate that dissociation of picolyl proceeds initially via a resonance-stabilized seven-membered ring.
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Affiliation(s)
- Engelbert Reusch
- Institute of Physical and Theoretical ChemistryUniversity of WürzburgAm Hubland Süd97074WürzburgGermany
| | - Fabian Holzmeier
- Dipartimento di FisicaPolitecnico di MilanoPiazza Leonardo da Vinci 3220133MilanoItaly
| | - Marius Gerlach
- Institute of Physical and Theoretical ChemistryUniversity of WürzburgAm Hubland Süd97074WürzburgGermany
| | - Ingo Fischer
- Institute of Physical and Theoretical ChemistryUniversity of WürzburgAm Hubland Süd97074WürzburgGermany
| | - Patrick Hemberger
- Laboratory for Femtochemistry and Synchrotron RadiationPaul Scherrer Institut (PSI)5232VilligenSwitzerland
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6
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Lam CS, Lau KC, Ng CY. High-Level Ab Initio Predictions for the Ionization Energy, Bond Dissociation Energies, and Heats of Formation of Vanadium Methylidyne Radical and Its Cation (VCH/VCH +). J Phys Chem A 2019; 123:7454-7462. [PMID: 31414807 DOI: 10.1021/acs.jpca.9b05493] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The ionization energy (IE) of VCH, the 0 K V-CH/VC-H bond dissociation energies (D0s), and the heats of formation at 0 K (ΔHf0°) and 298 K (ΔHf298°) for VCH/VCH+ are predicted by the wave function-based CCSDTQ/CBS approach. This composite-coupled cluster method includes full quadruple excitations in conjunction with the approximation to the complete basis set (CBS) limit. The contributions of zero-point vibrational energy, core-valence (CV) correlation, spin-orbit coupling, and scalar relativistic corrections are taken into account. The present calculations show that adiabatic IE(VCH) = 6.785 eV and demonstrate excellent agreement with an IE value of 6.774 7 ± 0.000 1 eV measured with two-color laser-pulsed field ionization-photoelectron spectroscopy. The CCSDT and MRCI+Q methods which include CV correlations give the best predictions of harmonic frequencies: ω2 (ω2+) (bending) = 534 (650) and 564 (641) cm-1 and the V-CH stretching ω3 (ω3+) = 835 (827) and 856 (857) cm-1 compared with the experimental values. In this work, we offer a streamlined CCSDTQ/CBS approach which shows an error limit (≤20 meV) matching with previous benchmarking efforts for reliable IE and D0 predictions for VCH/VCH+. The CCSDTQ/CBS D0(V+-CH) - D0(V-CH) = -0.012 eV and D0(VC+-H) - D0(VC-H) = 0.345 eV are in good accord with the experimentally derived values of -0.028 4 ± 0.000 1 and 0.355 9 ± 0.000 1 eV, respectively. The present study has demonstrated that the CCSDTQ/CBS protocol can be readily extended to investigate triatomic molecules containing 3d-metals.
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Affiliation(s)
- Chow-Shing Lam
- Department of Chemistry , City University of Hong Kong , Tat Chee Avenue , Kowloon , Hong Kong
| | - Kai-Chung Lau
- Department of Chemistry , City University of Hong Kong , Tat Chee Avenue , Kowloon , Hong Kong
| | - Cheuk-Yiu Ng
- Department of Chemistry , University of California, Davis , Davis , California 95616 , United States
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7
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Wu X, Zhou X, Hemberger P, Bodi A. The ionization energy of the vinyl radical: a Mexican standoff with a happy ending. Phys Chem Chem Phys 2019; 21:22238-22247. [DOI: 10.1039/c9cp04493k] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Theoretical approaches and experimental spectra are confirmed as the origin transition is shown to be forbidden in vinyl photoionization.
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Affiliation(s)
- Xiangkun Wu
- Laboratory for Femtochemistry and Synchrotron Radiation
- Paul Scherrer Institute
- 5232 Villigen
- Switzerland
- Hefei National Laboratory for Physical Sciences at the Microscale
| | - Xiaoguo Zhou
- Hefei National Laboratory for Physical Sciences at the Microscale
- Department of Chemical Physics
- University of Science and Technology of China
- Hefei 230026
- China
| | - Patrick Hemberger
- Laboratory for Femtochemistry and Synchrotron Radiation
- Paul Scherrer Institute
- 5232 Villigen
- Switzerland
| | - Andras Bodi
- Laboratory for Femtochemistry and Synchrotron Radiation
- Paul Scherrer Institute
- 5232 Villigen
- Switzerland
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8
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Mehnen B, Linguerri R, Ben Yaghlane S, Al Mogren MM, Hochlaf M. Disentangling the complex spectrum of the ethynyl cation. Faraday Discuss 2018; 212:51-64. [PMID: 30234210 DOI: 10.1039/c8fd00091c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The ethynyl cation, C2H+, is of great importance in astrophysical media and in combustion. It is involved in the formation of larger organic compounds and in their decomposition mechanisms. Here, we investigate the low-lying electronic states of this cation using pure ab initio methodologies. The evolution of its potential energy surfaces along the stretching and bending coordinates reveals a high density of electronic states that favours mutual interactions and the mixing of wavefunctions. The ground state is of 3Π space symmetry and the lowest singlet state (1Π) is found to be a quasi-linear-quasi-linear Renner-Teller system. Our work suggests that the (spin-)rovibronic spectrum of such a molecular system is complicated, because of the contributions of multiple couplings, including Renner-Teller, vibronic and spin-orbit. We also deduced the adiabatic ionization energy of the ethynyl radical, in good agreement with recent measurements. In summary, our work shows that the ethynyl cation, in spite of its small size, still represents a challenging molecular problem to be solved.
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Affiliation(s)
- B Mehnen
- Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallée, France. and Laboratoire de Spectroscopie Atomique, Moléculaire et Applications LSAMA, Université de Tunis El Manar, Tunis, Tunisia
| | - R Linguerri
- Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallée, France.
| | - S Ben Yaghlane
- Laboratoire de Spectroscopie Atomique, Moléculaire et Applications LSAMA, Université de Tunis El Manar, Tunis, Tunisia
| | - M Mogren Al Mogren
- Chemistry Department, Faculty of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Kingdom of Saudi Arabia
| | - M Hochlaf
- Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallée, France.
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9
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Lam CS, Lau KC, Ng CY. High-level ab initio predictions for the ionisation energy, bond dissociation energies and heats of formation of zirconium oxide and its cation (ZrO/ZrO +). Mol Phys 2018. [DOI: 10.1080/00268976.2018.1434906] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Chow-Shing Lam
- Department of Chemistry, City University of Hong Kong , Kowloon, Hong Kong
| | - Kai-Chung Lau
- Department of Chemistry, City University of Hong Kong , Kowloon, Hong Kong
| | - Cheuk-Yiu Ng
- Department of Chemistry, University of California, Davis , CA, USA
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10
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Pan Y, Luo Z, Chang YC, Lau KC, Ng CY. High-Level ab Initio Predictions for the Ionization Energies, Bond Dissociation Energies, and Heats of Formation of Titanium Oxides and Their Cations (TiOn/TiOn+, n = 1 and 2). J Phys Chem A 2017; 121:669-679. [DOI: 10.1021/acs.jpca.6b09491] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yi Pan
- Department
of Biology and Chemistry, City University of Hong Kong, Tat Chee
Avenue, Kowloon, Hong Kong
| | - Zhihong Luo
- Department
of Chemistry, University of California, Davis, California 95616, United States
| | - Yih-Chung Chang
- Department
of Chemistry, University of California, Davis, California 95616, United States
| | - Kai-Chung Lau
- Department
of Biology and Chemistry, City University of Hong Kong, Tat Chee
Avenue, Kowloon, Hong Kong
| | - C. Y. Ng
- Department
of Chemistry, University of California, Davis, California 95616, United States
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11
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Gans B, Garcia GA, Holzmeier F, Krüger J, Röder A, Lopes A, Fittschen C, Loison JC, Alcaraz C. Communication: On the first ionization threshold of the C 2H radical. J Chem Phys 2017; 146:011101. [PMID: 28063431 DOI: 10.1063/1.4973383] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The slow photoelectron spectrum of the ethynyl radical has been recorded for the first time by using the DESIRS beamline of the SOLEIL synchrotron facility. Ethynyl was generated using a microwave discharge flow tube. The observation of the X+Π3←XΣ+2 transition allowed the first direct measurement of the adiabatic ionization threshold of this radical (EI = 11.641(5) eV). The experimental results are supported by ab initio calculations. Our preliminary investigation of the cationic ground state potential energy surfaces predicts a non-negligible Renner-Teller effect which has not been discussed previously.
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Affiliation(s)
- B Gans
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France
| | - G A Garcia
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin BP 48, F-91192 Gif sur Yvette Cedex, France
| | - F Holzmeier
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - J Krüger
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin BP 48, F-91192 Gif sur Yvette Cedex, France
| | - A Röder
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - A Lopes
- Laboratoire de Chimie Physique, UMR 8000 CNRS, Univ. Paris-Sud, Univ. Paris-Saclay, Bât. 350, Centre Universitaire Paris-Sud, F-91405 Orsay Cedex, France
| | - C Fittschen
- Université Lille, CNRS, UMR 8522-PC2A-Physicochimie des Processus de Combustion et de l'Atmosphère, F-59000 Lille, France
| | - J-C Loison
- Institut des Sciences Moléculaires, UMR 5255 CNRS, Université de Bordeaux, Bât. A12, 351 cours de la Libération, F-33405 Talence Cedex, France
| | - C Alcaraz
- Laboratoire de Chimie Physique, UMR 8000 CNRS, Univ. Paris-Sud, Univ. Paris-Saclay, Bât. 350, Centre Universitaire Paris-Sud, F-91405 Orsay Cedex, France
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12
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Sánchez JP, Aguirre NF, Díaz-Tendero S, Martín F, Alcamí M. Structure, Ionization, and Fragmentation of Neutral and Positively Charged Hydrogenated Carbon Clusters: CnHmq+ (n = 1–5, m = 1–4, q = 0–3). J Phys Chem A 2016; 120:588-605. [DOI: 10.1021/acs.jpca.5b10143] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | | | - Fernando Martín
- Instituto
Madrileño de Estudios Avanzados en Nanociencias (IMDEA-Nanociencia), Cantoblanco, 28049 Madrid, Spain
| | - Manuel Alcamí
- Instituto
Madrileño de Estudios Avanzados en Nanociencias (IMDEA-Nanociencia), Cantoblanco, 28049 Madrid, Spain
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13
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He ZH, Chen J, Wu Q, Ji GF. Special catalytic effects of intermediate-water for rapid shock initiation of β-HMX. RSC Adv 2016. [DOI: 10.1039/c6ra21384g] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The intermediate-water efficiently promoted the decomposition of β-HMX, corresponding to a rapid shock initiation process.
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Affiliation(s)
- Zheng-Hua He
- National Key Laboratory of Shock Wave and Detonation Physics
- Institute of Fluid Physics
- China Academy of Engineering Physics
- Mianyang 621900
- China
| | - Jun Chen
- National Key Laboratory of Computational Physics
- Institute of Applied Physics and Computational Mathematics
- Beijing 100088
- China
- Center for Applied Physics and Technology
| | - Qiang Wu
- National Key Laboratory of Shock Wave and Detonation Physics
- Institute of Fluid Physics
- China Academy of Engineering Physics
- Mianyang 621900
- China
| | - Guang-Fu Ji
- National Key Laboratory of Shock Wave and Detonation Physics
- Institute of Fluid Physics
- China Academy of Engineering Physics
- Mianyang 621900
- China
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14
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Luo Z, Chang YC, Pan Y, Lau KC, Ng CY. Rotationally Resolved State-to-State Photoelectron Study of Molybdenum Monoxide Cation (MoO+). J Phys Chem A 2015; 120:4643-54. [DOI: 10.1021/acs.jpca.5b07939] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Zhihong Luo
- Department
of Chemistry, University of California, Davis, California 95616, United States
- Department
of Physics, Tsinghua University, Beijing 100084, China
| | - Yih-Chung Chang
- Department
of Chemistry, University of California, Davis, California 95616, United States
| | - Yi Pan
- Department
of Biology and Chemistry, City University of Hong Kong, 80 Tat
Chee Avenue, Kowloon, Hong Kong
| | - Kai-Chung Lau
- Department
of Biology and Chemistry, City University of Hong Kong, 80 Tat
Chee Avenue, Kowloon, Hong Kong
| | - C. Y. Ng
- Department
of Chemistry, University of California, Davis, California 95616, United States
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15
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Chang YC, Luo Z, Pan Y, Zhang Z, Song YN, Kuang SY, Yin QZ, Lau KC, Ng CY. Rotationally resolved state-to-state photoionization and the photoelectron study of vanadium monocarbide and its cations (VC/VC+). Phys Chem Chem Phys 2015; 17:9780-93. [DOI: 10.1039/c5cp00371g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Two-color VIS-UV laser pulsed filed ionization-photoelectron (PFI-PE) study and theoretical predictions for vanadium monocarbide (VC) neutral and its cation (VC+).
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Affiliation(s)
| | - Zhihong Luo
- Department of Chemistry
- University of California
- Davis
- USA
| | - Yi Pan
- Department of Biology and Chemistry
- City University of Hong Kong
- Kowloon
- Hong Kong
| | - Zheng Zhang
- Department of Chemistry
- University of California
- Davis
- USA
| | - Ying-Nan Song
- Department of Chemistry
- University of California
- Davis
- USA
| | | | - Qing Zhu Yin
- Department of Earth and Planetary Science
- University of California
- Davis
- USA
| | - Kai-Chung Lau
- Department of Biology and Chemistry
- City University of Hong Kong
- Kowloon
- Hong Kong
| | - C. Y. Ng
- Department of Chemistry
- University of California
- Davis
- USA
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16
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Leach S, Garcia GA, Mahjoub A, Bénilan Y, Fray N, Gazeau MC, Gaie-Levrel F, Champion N, Schwell M. Ionization photophysics and spectroscopy of cyanoacetylene. J Chem Phys 2014; 140:174305. [PMID: 24811639 DOI: 10.1063/1.4871298] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Photoionization of cyanoacetylene was studied using synchrotron radiation over the non-dissociative ionization excitation range 11-15.6 eV, with photoelectron-photoion coincidence techniques. The absolute ionization cross-section and spectroscopic aspects of the parent ion were recorded. The adiabatic ionization energy of cyanoacetylene was measured as 11.573 ± 0.010 eV. A detailed analysis of photoelectron spectra of HC3N involves new aspects and new assignments of the vibrational components to excitation of the A(2)Σ(+) and B(2)Π states of the cation. Some of the structured autoionization features observed in the 11.94 to 15.5 eV region of the total ion yield (TIY) spectrum were assigned to two Rydberg series converging to the B(2)Π state of HC3N(+). A number of the measured TIY features are suggested to be vibrational components of Rydberg series converging to the C(2)Σ(+) state of HC3N(+) at ≈17.6 eV and others to valence shell transitions of cyanoacetylene in the 11.6-15 eV region. The results of quantum chemical calculations of the cation electronic state geometries, vibrational frequencies and energies, as well as of the C-H dissociation potential energy profiles of the ground and electronic excited states of the ion, are compared with experimental observations. Ionization quantum yields are evaluated and discussed and the problem of adequate calibration of photoionization cross-sections is raised.
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Affiliation(s)
- Sydney Leach
- LERMA UMR CNRS 8112, Observatoire de Paris-Meudon, 5 place Jules-Jansen, 92195 Meudon, France
| | - Gustavo A Garcia
- Synchrotron SOLEIL, L'Orme des Merisiers, St. Aubin, B.P. 48, 91192, Gif-sur-Yvette Cedex, France
| | - Ahmed Mahjoub
- LISA UMR CNRS 7583, Université Paris Est Créteil and Université Paris Diderot, Institut Pierre Simon Laplace, 61 Avenue du Général de Gaulle, 94010 Créteil, France
| | - Yves Bénilan
- LISA UMR CNRS 7583, Université Paris Est Créteil and Université Paris Diderot, Institut Pierre Simon Laplace, 61 Avenue du Général de Gaulle, 94010 Créteil, France
| | - Nicolas Fray
- Synchrotron SOLEIL, L'Orme des Merisiers, St. Aubin, B.P. 48, 91192, Gif-sur-Yvette Cedex, France
| | - Marie-Claire Gazeau
- LISA UMR CNRS 7583, Université Paris Est Créteil and Université Paris Diderot, Institut Pierre Simon Laplace, 61 Avenue du Général de Gaulle, 94010 Créteil, France
| | - François Gaie-Levrel
- Synchrotron SOLEIL, L'Orme des Merisiers, St. Aubin, B.P. 48, 91192, Gif-sur-Yvette Cedex, France
| | - Norbert Champion
- LERMA UMR CNRS 8112, Observatoire de Paris-Meudon, 5 place Jules-Jansen, 92195 Meudon, France
| | - Martin Schwell
- LISA UMR CNRS 7583, Université Paris Est Créteil and Université Paris Diderot, Institut Pierre Simon Laplace, 61 Avenue du Général de Gaulle, 94010 Créteil, France
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Lo PK, Lau KC. High-Level ab Initio Predictions for the Ionization Energy, Electron Affinity, and Heats of Formation of Cyclopentadienyl Radical, Cation, and Anion, C5H5/C5H5+/C5H5–. J Phys Chem A 2014; 118:2498-507. [DOI: 10.1021/jp412323j] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Po-Kam Lo
- Department of Biology and
Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong
| | - Kai-Chung Lau
- Department of Biology and
Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong
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18
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Lau KC, Pan Y, Lam CS, Huang H, Chang YC, Luo Z, Shi X, Ng CY. High-level ab initio predictions for the ionization energy, bond dissociation energies, and heats of formation of cobalt carbide (CoC) and its cation (CoC+). J Chem Phys 2013; 138:094302. [DOI: 10.1063/1.4792718] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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Huzak M, Deleuze MS. Benchmark theoretical study of the electric polarizabilities of naphthalene, anthracene, and tetracene. J Chem Phys 2013; 138:024319. [DOI: 10.1063/1.4773018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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20
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Gao H, Lu Z, Yang L, Zhou J, Ng CY. Communication: A vibrational study of propargyl cation using the vacuum ultraviolet laser velocity-map imaging photoelectron method. J Chem Phys 2012; 137:161101. [PMID: 23126688 DOI: 10.1063/1.4764306] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
By employing the vacuum ultraviolet (VUV) laser velocity-map imaging photoelectron (VUV-VMI-PE) method, we have obtained a vibrationally resolved photoelectron spectrum of gaseous propargyl radical [C(3)H(3)(X(2)B(1))] in the energy range of 0-4600 cm(-1) above its ionization energy. The cold C(3)H(3) radicals were produced from a supersonically cooled radical beam source based on 193 nm ArF photodissociation of C(3)H(3)Cl. The VUV-VMI-PE spectrum of C(3)H(3) thus obtained reveals a Franck-Condon factor (FCF) pattern with a highly dominant origin band along with weak vibrational progressions associated with excitations of the C-C ν(5)(+)(a(1)) and C≡C ν(3)(+)(a(1)) symmetric stretching modes and the CCH ν(7)(+)(b(1)) out-of-plane bending mode of C(3)H(3)(+)(X(1)A(1)). The ν(5)(+)(a(1)) vibrational frequency of 1120 cm(-1) determined in the present study is lower than the value deduced from the recent Ar-tagged infrared photodissociation study by 102 cm(-1), confirming the highly accurate vibrational frequency predictions obtained by the most recent state-of-the-art ab initio quantum calculations. The observation of the FCF disallowed ν(7)(+)(b(1)) mode is indicative of vibronic interactions. The discrepancy observed between the FCF pattern determined in the present study and that predicted by a recent high-level quantum theoretical investigation can be taken as evidence that the potential energy surfaces used in the latter theoretical study are in need of improvement in order to provide a reliable FCF prediction for the C(3)H(3)/C(3)H(3)(+) photoionization system.
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Affiliation(s)
- Hong Gao
- Department of Chemistry, University of California, Davis, California 95616, USA
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21
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Huzak M, Hajgató B, Deleuze M. Benchmark theoretical study of the ionization energies, electron affinities and singlet–triplet energy gaps of azulene, phenanthrene, pyrene, chrysene and perylene. Chem Phys 2012. [DOI: 10.1016/j.chemphys.2012.08.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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22
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Yu H, Evans NL, Stavros VG, Ullrich S. Investigation of multiple electronic excited state relaxation pathways following 200 nm photolysis of gas-phase imidazole. Phys Chem Chem Phys 2012; 14:6266-72. [PMID: 22370631 DOI: 10.1039/c2cp23533a] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Imidazole acts as a subunit in the DNA base adenine and the amino acid histidine-both important biomolecules which display low fluorescence quantum yields following UV excitation. The low fluorescence quantum yields are attributed to competing non-radiative excited state relaxation pathways that operate on ultrafast timescales. Imidazole is investigated here as a model compound due to its accessibility to high level ab initio calculations and time-resolved gas-phase spectroscopic techniques. Recent non-adiabatic dynamics simulations have identified three non-radiative relaxation mechanisms which are active following 6.0-6.2 eV excitation. Presented herein is a comprehensive investigation of each mechanism using a combination of femtosecond time-resolved ion yield and total kinetic energy release spectroscopies to monitor the formation of associated photoproducts. Relaxation along the (1)πσ state constitutes the predominant deactivation pathway. Timescales for NH-dissociation are extracted and distinguished from alternative H-atom sources based on their kinetic energy distributions. Larger photoproducts are observed to a lesser extent and attributed to ring fragmentation following NH-puckering and CN-stretching relaxation paths.
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Affiliation(s)
- Hui Yu
- Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602, USA
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23
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Lau KC, Ng CY. Note: Accurate ab initio predictions of ionization energies of propargyl and allyl radicals: Revisited. J Chem Phys 2011; 135:246101. [DOI: 10.1063/1.3673443] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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24
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Gao H, Xu Y, Yang L, Lam CS, Wang H, Zhou J, Ng CY. High-resolution threshold photoelectron study of the propargyl radical by the vacuum ultraviolet laser velocity-map imaging method. J Chem Phys 2011; 135:224304. [DOI: 10.1063/1.3664864] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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25
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Hajgató B, Huzak M, Deleuze MS. Focal Point Analysis of the Singlet–Triplet Energy Gap of Octacene and Larger Acenes. J Phys Chem A 2011; 115:9282-93. [DOI: 10.1021/jp2043043] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Balázs Hajgató
- Research Group of Theoretical Chemistry and Molecular Modelling, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium
| | - Matija Huzak
- Research Group of Theoretical Chemistry and Molecular Modelling, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium
| | - Michael S. Deleuze
- Research Group of Theoretical Chemistry and Molecular Modelling, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium
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26
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Lam CS, Wang H, Xu Y, Lau KC, Ng CY. A vacuum-ultraviolet laser pulsed field ionization-photoelectron study of sulfur monoxide (SO) and its cation (SO+). J Chem Phys 2011; 134:144304. [DOI: 10.1063/1.3575227] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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27
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Hemberger P, Lang M, Noller B, Fischer I, Alcaraz C, Cunha de Miranda BK, Garcia GA, Soldi-Lose H. Photoionization of Propargyl and Bromopropargyl Radicals: A Threshold Photoelectron Spectroscopic Study. J Phys Chem A 2011; 115:2225-30. [DOI: 10.1021/jp112110j] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Patrick Hemberger
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Melanie Lang
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Bastian Noller
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Ingo Fischer
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Christian Alcaraz
- Laboratoire de Chimie-Physique, UMR 8000 CNRS & Université Paris-Sud 11, F-91405 Orsay Cedex, France
| | - Bárbara K. Cunha de Miranda
- Laboratoire de Chimie-Physique, UMR 8000 CNRS & Université Paris-Sud 11, F-91405 Orsay Cedex, France
- Laboratório de Espectroscopia e Laser, Instituto de Física, Universidade Federal Fluminense, 24210- 340, Niterói, RJ, Brazil
| | - Gustavo A. Garcia
- Synchrotron SOLEIL, L’Orme des Merisiers, Saint Aubin - BP 48, F-91192 Gif-sur-Yvette Cedex, France
| | - Héloïse Soldi-Lose
- Synchrotron SOLEIL, L’Orme des Merisiers, Saint Aubin - BP 48, F-91192 Gif-sur-Yvette Cedex, France
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28
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Lo PK, Lau KC. High-Level ab Initio Predictions for the Ionization Energies and Heats of Formation of Five-Membered-Ring Molecules: Thiophene, Furan, Pyrrole, 1,3-Cyclopentadiene, and Borole, C4H4X/C4H4X+ (X = S, O, NH, CH2, and BH). J Phys Chem A 2011; 115:932-9. [DOI: 10.1021/jp110499c] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Po-Kam Lo
- Department of Biology and Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong
| | - Kai-Chung Lau
- Department of Biology and Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong
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29
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Botschwina P, Oswald R. Calculated photoelectron spectra of isotopomers of the propargyl radical (H2C3H): An explicitly correlated coupled cluster study. Chem Phys 2010. [DOI: 10.1016/j.chemphys.2010.07.030] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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30
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Lau KC, Chang YC, Shi X, Ng CY. High-level ab initio predictions for the ionization energy, bond dissociation energies, and heats of formation of nickel carbide (NiC) and its cation (NiC+). J Chem Phys 2010; 133:114304. [DOI: 10.1063/1.3479759] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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31
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Chang YC, Shi X, Lau KC, Yin QZ, Liou HT, Ng CY. Rovibronically selected and resolved two-color laser photoionization and photoelectron study of nickel carbide cation. J Chem Phys 2010; 133:054310. [DOI: 10.1063/1.3464488] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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32
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Hajgató B, Szieberth D, Geerlings P, De Proft F, Deleuze MS. A benchmark theoretical study of the electronic ground state and of the singlet-triplet split of benzene and linear acenes. J Chem Phys 2009; 131:224321. [DOI: 10.1063/1.3270190] [Citation(s) in RCA: 173] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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33
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Lau KC, Chang YC, Lam CS, Ng CY. High-Level ab Initio Predictions for the Ionization Energy, Bond Dissociation Energies, and Heats of Formations of Iron Carbide (FeC) and Its Cation (FeC+). J Phys Chem A 2009; 113:14321-8. [DOI: 10.1021/jp903218h] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kai-Chung Lau
- Department of Biology and Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, and Department of Chemistry, University of California, Davis, Davis, California 95616
| | - Yih-Chung Chang
- Department of Biology and Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, and Department of Chemistry, University of California, Davis, Davis, California 95616
| | - Chow-Shing Lam
- Department of Biology and Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, and Department of Chemistry, University of California, Davis, Davis, California 95616
| | - C. Y. Ng
- Department of Biology and Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, and Department of Chemistry, University of California, Davis, Davis, California 95616
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34
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35
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Noller B, Hemberger P, Fischer I, Alcaraz C, Garcia GA, Soldi-Lose H. The photoionisation of two phenylcarbenes and their diazirine precursors investigated using synchrotron radiation. Phys Chem Chem Phys 2009; 11:5384-91. [DOI: 10.1039/b823269e] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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36
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Hou Y, Woo HK, Wang P, Xing X, Ng CY, Lau KC. Vacuum ultraviolet pulsed field ionization-photoelectron and infrared-photoinduced Rydberg ionization study of trans-1,3-butadiene. J Chem Phys 2008; 129:114305. [DOI: 10.1063/1.2973635] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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37
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Lau KC, Zheng W, Wong NB, Li WK. Theoretical prediction of the ionization energies of the C4H7 radicals: 1-Methylallyl, 2-methylallyl, cyclopropylmethyl, and cyclobutyl radicals. J Chem Phys 2007; 127:154302. [DOI: 10.1063/1.2774972] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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38
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Zhang T, Tang XN, Lau KC, Ng CY, Nicolas C, Peterka DS, Ahmed M, Morton ML, Ruscic B, Yang R, Wei LX, Huang CQ, Yang B, Wang J, Sheng LS, Zhang YW, Qi F. Direct identification of propargyl radical in combustion flames by vacuum ultraviolet photoionization mass spectrometry. J Chem Phys 2007; 124:74302. [PMID: 16497031 DOI: 10.1063/1.2168448] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have developed an effusive laser photodissociation radical source, aiming for the production of vibrationally relaxed radicals. Employing this radical source, we have measured the vacuum ultraviolet (VUV) photoionization efficiency (PIE) spectrum of the propargyl radical (C(3)H(3)) formed by the 193 nm excimer laser photodissociation of propargyl chloride in the energy range of 8.5-9.9 eV using high-resolution (energy bandwidth = 1 meV) multibunch synchrotron radiation. The VUV-PIE spectrum of C(3)H(3) thus obtained is found to exhibit pronounced autoionization features, which are tentatively assigned as members of two vibrational progressions of C(3)H(3) in excited autoionizing Rydberg states. The ionization energy (IE = 8.674 +/- 0.001 eV) of C(3)H(3) determined by a small steplike feature resolved at the photoionization onset of the VUV-PIE spectrum is in excellent agreement with the IE value reported in a previous pulsed field ionization-photoelectron study. We have also calculated the Franck-Condon factors (FCFs) for the photoionization transitions C(3)H(3) (+)(X;nu(i),i = 1-12)<--C(3)H(3)(X). The comparison between the pattern of FCFs and the autoionization peaks resolved in the VUV-PIE spectrum of C(3)H(3) points to the conclusion that the resonance-enhanced autoionization mechanism is most likely responsible for the observation of pronounced autoionization features. We also present here the VUV-PIE spectra for the mass 39 ions observed in the VUV synchrotron-based photoionization mass spectrometric sampling of several premixed flames. The excellent agreement of the IE value and the pattern of autoionizing features of the VUV-PIE spectra observed in the photodissociation and flames studies has provided an unambiguous identification of the propargyl radical as an important intermediate in the premixed combustion flames. The discrepancy found between the PIE spectra obtained in flames and photodissociation at energies above the IE(C(3)H(3)) suggests that the PIE spectra obtained in flames might have contributions from the photoionization of vibrationally excited C(3)H(3) and/or the dissociative photoionization processes involving larger hydrocarbon species formed in flames.
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Affiliation(s)
- T Zhang
- Department of Chemistry, University of California at Davis, 95616, USA
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39
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Kaiser RI, Belau L, Leone SR, Ahmed M, Wang Y, Braams BJ, Bowman JM. A Combined Experimental and Computational Study on the Ionization Energies of the Cyclic and Linear C3H Isomers. Chemphyschem 2007; 8:1236-9. [PMID: 17429825 DOI: 10.1002/cphc.200700109] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
For the first time, two hydrogen-deficient hydrocarbon radicals are generated in situ via laser ablation of graphite and seeding the ablated species in acetylene gas, which acts as a carrier and reactant simultaneously. By recording photoionization efficiency curves (PIE) and simulating the experimental spectrum with computed Franck-Condon (FC) factors, we can reproduce the general pattern of the PIE curve of m/z=37. We recover ionization energies of 9.15 eV and 9.76 eV for the linear and cyclic isomers, respectively. Our combined experimental and theoretical studies provide an unprecedented, versatile pathway to investigate the ionization energies of even more complex hydrocarbon radicals in situ, which are difficult to prepare by classical synthesis, in future experiments.
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Affiliation(s)
- Ralf I Kaiser
- University of Hawaii at Manoa, Department of Chemistry, Honolulu, HI 96822, USA.
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40
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Li J, Yang J, Mo Y, Lau KC, Qian XM, Song Y, Liu J, Ng CY. Combined vacuum ultraviolet laser and synchrotron pulsed field ionization study of CH2BrCl. J Chem Phys 2007; 126:184304. [PMID: 17508800 DOI: 10.1063/1.2730829] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The pulsed field ionization-photoelectron (PFI-PE) spectrum of bromochloromethane (CH2BrCl) in the region of 85,320-88,200 cm-1 has been measured using vacuum ultraviolet laser. The vibrational structure resolved in the PFI-PE spectrum was assigned based on ab initio quantum chemical calculations and Franck-Condon factor predictions. At energies 0-1400 cm-1 above the adiabatic ionization energy (IE) of CH2BrCl, the Br-C-Cl bending vibration progression (nu1+=0-8) of CH2BrCl+ is well resolved and constitutes the major structure in the PFI-PE spectrum, whereas the spectrum at energies 1400-2600 cm-1 above the IE(CH2BrCl) is found to exhibit complex vibrational features, suggesting perturbation by the low lying excited CH2BrCl+(A 2A") state. The assignment of the PFI-PE vibrational bands gives the IE(CH2BrCl)=85,612.4+/-2.0 cm-1 (10.6146+/-0.0003 eV) and the bending frequencies nu1+(a1')=209.7+/-2.0 cm-1 for CH2BrCl+(X2A'). We have also examined the dissociative photoionization process, CH2BrCl+hnu-->CH2Cl++Br+e-, in the energy range of 11.36-11.57 eV using the synchrotron based PFI-PE-photoion coincidence method, yielding the 0 K threshold or appearance energy AE(CH2Cl+)=11.509+/-0.002 eV. Combining the 0 K AE(CH2Cl+) and IE(CH2BrCl) values obtained in this study, together with the known IE(CH2Cl), we have determined the 0 K bond dissociation energies (D0) for CH2Cl+-Br (0.894+/-0.002 eV) and CH2Cl-Br (2.76+/-0.01 eV). We have also performed CCSD(T, full)/complete basis set (CBS) calculations with high-level corrections for the predictions of the IE(CH2BrCl), AE(CH2Cl+), IE(CH2Cl), D0(CH2Cl+-Br), and D0(CH2Cl-Br). The comparison between the theoretical predictions and experimental determinations indicates that the CCSD(T, full)/CBS calculations with high-level corrections are highly reliable with estimated error limits of <17 meV.
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Affiliation(s)
- Juan Li
- Key Laboratory for Atomic and Molecular Nanosciences, Department of Physics, Tsinghua University, Beijing 10084, China
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41
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Xing X, Reed B, Lau KC, Ng CY, Zhang X, Ellison GB. Vacuum ultraviolet laser pulsed field ionization-photoelectron study of allyl radical CH2CHCH2. J Chem Phys 2007; 126:171101. [PMID: 17492849 DOI: 10.1063/1.2737443] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The pulsed field ionization-photoelectron (PFI-PE) spectrum of allyl radical CH2CHCH2 (C3H5) in the energy range of 65 200-66 600 cm-1 has been measured using vacuum ultraviolet laser. Based on the simulation of the rotational structures resolved in the vibrational PFI-PE bands of C3H5+(X 1A1;0(0+) and nu7+=1), the ionization energies (IEs) of C3H5(X 2A2;0(0)) to form C3H5+(X 1A1;0(0+) and nu7+=1) are determined to be 65 584.6+/-2.0 cm-1 (8.131 46+/-0.000 25 eV) and 66 020.9+/-2.0 cm-1 (8.185 56+/-0.000 25 eV), respectively, where nu7+(a1) is the symmetric C-C-C bending mode of C3H5+(X 1A1). These values are compared to IE(C3H5) values obtained in previous experimental and high-level ab initio quantum theoretical studies.
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Affiliation(s)
- Xi Xing
- Department of Chemistry, University of California, Davis, Davis, California 95616
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42
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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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Willitsch S, Merkt F, Kállay M, Gauss J. Thermochemical properties of small open-shell systems: experimental and high-levelab initioresults for NH2and. Mol Phys 2006. [DOI: 10.1080/13895260500518551] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Taatjes CA. Uncovering the Fundamental Chemistry of Alkyl + O2Reactions via Measurements of Product Formation. J Phys Chem A 2006; 110:4299-312. [PMID: 16571032 DOI: 10.1021/jp056997f] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reactions of alkyl radicals (R) with molecular oxygen (O(2)) are critical components in chemical models of tropospheric chemistry, hydrocarbon flames, and autoignition phenomena. The fundamental kinetics of the R + O(2) reactions is governed by a rich interplay of elementary physical chemistry processes. At low temperatures and moderate pressures, the reactions form stabilized alkylperoxy radicals (RO(2)), which are key chain carriers in the atmospheric oxidation of hydrocarbons. At higher temperatures, thermal dissociation of the alkylperoxy radicals becomes more rapid and the formation of hydroperoxyl radicals (HO(2)) and the conjugate alkenes begins to dominate the reaction. Internal isomerization of the RO(2) radicals to produce hydroperoxyalkyl radicals, often denoted by QOOH, leads to the production of OH and cyclic ether products. More crucially for combustion chemistry, reactions of the ephemeral QOOH species are also thought to be the key to chain branching in autoignition chemistry. Over the past decade, the understanding of these important reactions has changed greatly. A recognition, arising from classical kinetics experiments but firmly established by recent high-level theoretical studies, that HO(2) elimination occurs directly from an alkylperoxy radical without intervening isomerization has helped resolve tenacious controversies regarding HO(2) formation in these reactions. Second, the importance of including formally direct chemical activation pathways, especially for the formation of products but also for the formation of the QOOH species, in kinetic modeling of R + O(2) chemistry has been demonstrated. In addition, it appears that the crucial rate coefficient for the isomerization of RO(2) radicals to QOOH may be significantly larger than previously thought. These reinterpretations of this class of reactions have been supported by comparison of detailed theoretical calculations to new experimental results that monitor the formation of products of hydrocarbon radical oxidation following a pulsed-photolytic initiation. In this article, these recent experiments are discussed and their contributions to improving general models of alkyl + O(2) reactions are highlighted. Finally, several prospects are discussed for extending the experimental investigations to the pivotal questions of QOOH radical chemistry.
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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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C. Lau K, Ng CY. Accurate ab initio Predictions of Ionization Energies and Heats of Formation for Cyclopropenylidene, Propargylene and Propadienylidene. CHINESE J CHEM PHYS 2006. [DOI: 10.1360/cjcp2006.19(1).29.10] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Lago AF, Baer T. A Photoelectron Photoion Coincidence Study of the Vinyl Bromide and Tribromoethane Ion Dissociation Dynamics: Heats of Formation of C2H3+, C2H3Br, C2H3Br+, C2H3Br2+, and C2H3Br3. J Phys Chem A 2005; 110:3036-41. [PMID: 16509625 DOI: 10.1021/jp053943x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The threshold photoelectron photoion coincidence (TPEPICO) technique has been used to measure accurate dissociative photoionization onsets of vinyl bromide and 1,1,2-tribromoethane. The reactions investigated and their 0 K onsets are C2H3Br + hnu --> C2H3+ + Br (11.902 +/- 0.008 eV); C2H3Br3 + hnu --> C2H3Br2+ + Br (10.608 +/- 0.008 eV); and (C2H3Br3 + hnu --> C2H3Br+ + 2Br (12.301 +/- 0.035 eV). The vinyl ion heat of formation (Delta(f)H degrees 298K = 1116.1 +/- 3.0 kJ/mol) has been calculated using W1 theory and used as an anchor along with the measured dissociation energies to determine the heats of formation, Delta(f)H degrees 298K, in kJ/mol, of the following bromine-containing species: C2H3Br (74.1 +/- 3.1), C2H3Br+ (1021.9 +/- 3.1), C2H3Br2+ (967.1 +/- 4.0), and C2H3Br3 (53.5 +/- 4.3). These results represent accurate and consistent experimental determinations of heats of formation for these bromine-containing species, which serve to correct the discrepancies in the literature for C2H3Br and C2H3Br+ and provide the first experimental determination for the enthalpies of formation of C2H3Br2+ and C2H3Br3.
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Affiliation(s)
- A F Lago
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA
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