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Matsugi A, Suzuki S. Ring Growth Mechanism in the Reaction between Fulvenallenyl and Cyclopentadienyl Radicals. J Phys Chem A 2024; 128:1327-1338. [PMID: 38351621 DOI: 10.1021/acs.jpca.3c07441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Recombination between resonance-stabilized hydrocarbon radicals is an important class of reactions that contribute to molecular growth chemistry in combustion. In the present study, the ring growth mechanism in the reaction between fulvenallenyl (C7H5) and cyclopentadienyl (C5H5) radicals is investigated computationally. The reaction pathways are explored by quantum chemical calculations, and the phenomenological and steady-state rate constants are determined by solving the multiple-well master equations. The primary reaction routes following the recombination between the two radicals are found to be as follows: formation of the adducts, isomerization by hydrogen shift reactions, cyclization to form tricyclic compounds, and their isomerization and dissociation reactions, leading to the formation of acenaphthylene. The overall process can be approximately represented as C7H5 + C5H5 → acenaphthylene + 2H with the bimolecular rate constant of about 4 × 10-12 cm3 molecule-1 s-1. A reaction mechanism consisting of 20 reactions, including the formation, isomerization, and dissociation processes of major intermediate species, is proposed for use in kinetic modeling.
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Affiliation(s)
- Akira Matsugi
- Research Institute of Science for Safety and Sustainability, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba 305-8569, Japan
| | - Shunsuke Suzuki
- Research Institute for Energy Conversion, National Institute of Advanced Industrial Science and Technology (AIST), 1-2-1 Namiki, Tsukuba 305-8564, Japan
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2
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Izato YI, Matsugi A, Koshi M, Miyake A. Computation of entropy values for non-electrolyte solute molecules in solution based on semi-empirical corrections to a polarized continuum model. Phys Chem Chem Phys 2023; 25:8082-8089. [PMID: 36876720 DOI: 10.1039/d2cp04972d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Abstract
A simple heuristic model was developed for estimating the entropy of a solute molecule in an ideal solution based on quantum mechanical calculations with polarizable continuum models (QM/PCMs). A translational term was incorporated that included free-volume compensation for the Sackur-Tetrode equation and a rotational term was modeled based on the restricted rotation of a dipole in an electrostatic field. The configuration term for the solute at a given concentration was calculated using a simple lattice model that considered the number of configurations of the solute within the lattice. The configurational entropy was ascertained from this number based on Boltzmann's principle. Standard entropy values were determined for 41 combinations of solutes and solvents at a set concentration of 1 mol dm-3 using the proposed model, and the computational values were compared with experimental data. QM/PCM calculations were conducted at the ωB97X-D/6-311++G(d,p)/IEF-PCM level using universal force field van der Waals radii scaled by 1.2. The proposed model accurately reproduced the entropy values reported for solutes in non-aqueous solvents within a mean absolute deviation of 9.2 J mol-1 K-1 for 33 solutions. This performance represents a considerable improvement relative to that obtained using the method based on the ideal gas treatment that is widely utilized in commercially available computation packages. In contrast, computations for aqueous molecules overestimated the entropies because hydrophobic effects that decrease the entropy of aqueous solutions were not included in the present model.
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Affiliation(s)
- Yu-Ichiro Izato
- Graduate School of Information and Environment Sciences, Yokohama National University, 79-7 Tokiwadai, Hodogaya-ku, Yokohama, Japan.
| | - Akira Matsugi
- National Institute of Advanced Industrial Sciences and Technology, 16-1 Onogawa, Tsukuba, Ibaraki, Japan
| | - Mitsuo Koshi
- Professor Emeritus, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan
| | - Atsumi Miyake
- Graduate School of Information and Environment Sciences, Yokohama National University, 79-7 Tokiwadai, Hodogaya-ku, Yokohama, Japan.
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3
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Abstract
An attempt is made to evaluate the nonstatistical effects in the thermal decomposition of hydrogen peroxide (H2O2). Previous experimental studies on this reaction reported an unusual pressure dependence of the rate constant indicating broader falloff behavior than expected from conventional theory. In this work, the possibility that the rate constant is affected by nonstatistical effects is investigated based on classical trajectory calculations on the global potential energy surfaces of H2O2 and H2O2 + Ar. The emphasis is on the intramolecular energy redistribution from the K-rotor, that is, the external rotor for rotation around the principal axis of least moment of inertia. The calculations for the H2O2 molecules excited above the dissociation threshold suggest that the energy redistribution from the torsion and K-rotor to vibrations can be competitive with dissociation. In particular, the slow redistribution of the energy associated with the K-rotor significantly affects the dissociation rate. The successive trajectory calculations for collisions of H2O2 with Ar show that the energy associated with the K-rotor can be collisionally transferred more efficiently than the vibrational energy. On the basis of these results and several assumptions, a simple model is proposed to account for the nonstatistical effects on the pressure-dependent thermal rate constants. The model predicts significant broadening of the falloff curve of the rate constants but still cannot fully explain the experimental data.
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Affiliation(s)
- Akira Matsugi
- National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
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4
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Abstract
Multichannel thermal decomposition reactions of n-propyl radicals, 1-pentyl radicals, and toluene are investigated by solving a two-dimensional master equation formulated as a function of total energy (E) and angular momentum (J). The primary aim of this study is to elucidate the role of angular momentum in the kinetics of multichannel unimolecular reactions. The collisional transition processes of the reactants colliding with argon are characterized based on the classical trajectory calculations and implemented in the master equation. The rate constants calculated by using the two-dimensional master equation are compared with those of one-dimensional master equations. The consequence of the explicit treatment of angular momentum depends on the J dependence of the microscopic rate constants and is particularly emphasized in the thermal decomposition of toluene, for which the C-H and C-C bond fission channels are considered. The centrifugal effect is insignificant in the energetically favored C-H bond fission but is substantial in the energetically higher C-C bond fission, which causes rotational channel switching of the microscopic rate constants. The proper treatment of the J-dependent channel coupling effect, weak collisional transfer of J, and initial-J-dependent collisional energy transfer are found to be essential for predicting the branching fractions at low pressures.
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Affiliation(s)
- Akira Matsugi
- National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
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5
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Matsugi A. Modeling Collisional Transitions in Thermal Unimolecular Reactions: Successive Trajectories and Two-Dimensional Master Equation for Trifluoromethane Decomposition in an Argon Bath. J Phys Chem A 2020; 124:6645-6659. [PMID: 32786667 DOI: 10.1021/acs.jpca.0c05906] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Collisional transition processes in thermal unimolecular reactions are modeled by collision frequency, Z, and probability distribution function, P(E, J; E', J'), which describes the probabilities of collisional transitions from the initial state specified by the total energy and angular momentum, (E', J'), to the final states, (E, J). The validity of the collisional transition model, consisting of Z and P(E, J; E', J'), is assessed here for the title reaction. The present model and its parameters are derived from the moments of transition probabilities calculated by classical trajectory simulations. The model explicitly accounts for coupling between the energy and angular momentum transfer and the dependence of transition probability on the initial state. The performance of the model is evaluated by comparing the rate constants calculated by solving the two-dimensional master equation with those obtained from the classical trajectory calculations of the sequence of successive collisions. The rate constants are also compared with available experimental data. The present collisional transition model is found to perform fairly well for predicting the pressure-dependent rate constants. The uncertainty in the prediction and sensitivities of the rate constants to the model parameters are discussed. A simplified version of the model is proposed, which performs as well as the full model. The simplifications and robust procedures for calculating the model parameters are described.
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Affiliation(s)
- Akira Matsugi
- National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
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6
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Matsugi A. A high-repetition-rate shock tube for transient absorption and laser-induced fluorescence studies of high-temperature chemical kinetics. Rev Sci Instrum 2020; 91:054101. [PMID: 32486712 DOI: 10.1063/5.0007394] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 04/09/2020] [Indexed: 06/11/2023]
Abstract
A newly constructed high-repetition-rate shock tube designed for kinetic studies of high-temperature reactions using spectroscopic methods is described. The instrument operates at a 0.2-Hz cycle rate with a high reproducibility of reaction conditions that permits extensive signal averaging to improve the quality of kinetic trace data. The density and temperature of the gas behind the reflected shock wave are examined by probing the product formation from reference reactions. Two types of experimental techniques are implemented: transient absorption spectroscopy and time-resolved laser-induced fluorescence. Both methods are shown to be suitable for kinetic measurements of elementary reactions, as illustrated by their application in thermal decomposition reactions of the benzyl radicals and trifluoromethane.
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Affiliation(s)
- Akira Matsugi
- National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
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7
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Abstract
Understanding the mechanism of high-temperature reactions of aromatic hydrocarbons and radicals is essential for the modeling of hydrocarbon growth processes in combustion environments. In this study, the thermal decomposition reaction of benzyl radicals was investigated using time-resolved broadband cavity-enhanced absorption spectroscopy behind reflected shock waves at a postshock pressure of 100 kPa and temperatures of 1530, 1630, and 1740 K. The transient absorption spectra during the decomposition were recorded over the spectral range of 282-410 nm. The spectra were contributed by the absorption of benzyl radicals and some transient and residual absorbing species. The temporal behavior of the absorption was analyzed using a kinetic model to determine the rate constant for benzyl decomposition. The obtained rate constants can be represented by the Arrhenius expression k1 = 1.1 × 1012 exp(-30 500 K/T) s-1 with an estimated logarithmic uncertainty of Δlog10 k = ±0.2. Kinetic simulation of the secondary reactions indicated that fulvenallenyl radicals are potentially responsible for the transient absorption that appeared around 400 nm. This assignment is consistent with the available spectroscopic information of this radical. Possible candidates for the residual absorbing species are presented, suggesting the potential importance of ortho-benzyne as a reactive intermediate.
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Affiliation(s)
- Akira Matsugi
- National Institute of Advanced Industrial Science and Technology (AIST) , 16-1 Onogawa , Tsukuba , Ibaraki 305-8569 , Japan
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8
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Abstract
The air-water interface plays central roles in "on-droplet" synthesis, living systems, and the atmosphere; however, what makes reactions at the interface specific is largely unknown. Here, we examined carbocationic reactions of monoterpene (C10H16 isomer) on an acidic water microjet by using spray ionization mass spectrometry. Gaseous monoterpenes are trapped in the uppermost layers of a water surface via proton transfer and then undergo a chain-propagation reaction. The oligomerization pathway of β-pinene (β-P), which showed prompt chain-propagation, is examined by simultaneous exposure to camphene (CMP). (CMP)H+ is the most stable isomer formed via rearrangement of (β-P)H+ in the gas phase; however, no co-oligomerization was observed. This indicates that the oligomerization of (β-P)H+ proceeded via ring-opening isomerization. Quantum chemical calculations for [carbocation-(H2O)n=1,2] complexes revealed that the ring-opened isomer is stabilized by hydrogen-π bonds. We propose that partial hydration is a key factor that makes the interfacial reaction unique.
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Affiliation(s)
- Shinnosuke Ishizuka
- National Institute for Environmental Studies , 16-2 Onogawa , Tsukuba 305-8506 , Japan
| | - Akira Matsugi
- Research Institute of Science for Safety and Sustainability , National Institute of Advanced Industrial Science and Technology , 16-1 Onogawa , Tsukuba 305-8569 , Japan
| | - Tetsuya Hama
- Institute of Low Temperature Science , Hokkaido University , Kita-19 Nishi-8 , Sapporo 060-0819 , Japan
| | - Shinichi Enami
- National Institute for Environmental Studies , 16-2 Onogawa , Tsukuba 305-8506 , Japan
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9
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Matsugi A, Kubota S, Funato Y, Miura Y, Tonari K. Gas-phase reaction mechanism in chemical dry etching using NF 3 and remotely discharged NH 3/N 2 mixture. RSC Adv 2020; 10:30806-30814. [PMID: 35516038 PMCID: PMC9056326 DOI: 10.1039/d0ra05726f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 07/28/2020] [Indexed: 11/24/2022] Open
Abstract
Modeling of dry etching processes requires a detailed understanding of the relevant reaction mechanisms. This study aims to elucidate the gas-phase mechanism of reactions in the chemical dry etching process of SiO2 layers which is initiated by mixing NF3 gas with the discharged flow of an NH3/N2 mixture in an etching chamber. A kinetic model describing the gas-phase reactions has been constructed based on the predictions of reaction channels and rate constants by quantum chemical and statistical reaction-rate calculations. The primary reaction pathway includes the reaction of NF3 with H atoms, NF3 + H → NF2 + HF, and subsequent reactions involving NF2 and other radicals. The reaction pathways were analyzed by kinetic simulation, and a simplified kinetic model composed of 12 reactions was developed. The surface process was also investigated based on preliminary quantum chemical calculations for ammonium fluoride clusters, which are considered to contribute to etching. The results indicate the presence of negatively charged fluorine atoms in the clusters, which are suggested to serve as etchants to remove SiO2 from the surface. Reactions of NF3 and a discharged NH3/N2 mixture generate etchant species for destroying SiO2 layers.![]()
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Affiliation(s)
- Akira Matsugi
- National Institute of Advanced Industrial Science and Technology (AIST)
- Tsukuba
- Japan
| | - Shiro Kubota
- National Institute of Advanced Industrial Science and Technology (AIST)
- Tsukuba
- Japan
| | - Yuichi Funato
- Institute of Advanced Technology
- ULVAC, Inc
- Chigasaki
- Japan
| | - Yutaka Miura
- Institute of Advanced Technology
- ULVAC, Inc
- Chigasaki
- Japan
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10
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Affiliation(s)
- Akira Matsugi
- National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
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11
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Izato YI, Matsugi A, Koshi M, Miyake A. A simple heuristic approach to estimate the thermochemistry of condensed-phase molecules based on the polarizable continuum model. Phys Chem Chem Phys 2019; 21:18920-18929. [DOI: 10.1039/c9cp03226f] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A simple model based on a quantum chemical approach with polarizable continuum models (PCMs) to provide reasonable translational and rotational entropies for liquid phase molecules was developed.
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Affiliation(s)
- Yu-ichiro Izato
- Graduate School of Information and Environment Sciences
- Yokohama National University
- Yokohama
- Japan
| | - Akira Matsugi
- National Institute of Advanced Industrial Sciences and Technology
- Ibaraki
- Japan
| | - Mitsuo Koshi
- Department of Chemical System Engineering
- The University of Tokyo
- Tokyo
- Japan
| | - Atsumi Miyake
- Institute of Advanced Sciences
- Yokohama National University
- Yokohama
- Japan
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12
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Abstract
Pressure dependence of unimolecular reaction rates is governed by the energy transfer in collisions of reactants with bath gas molecules. Pressure-dependent rate constants can be theoretically determined by solving master equations for unimolecular reactions. In general, master equation formulations describe energy transfer processes using a collision frequency and a probability distribution model of the energy transferred per collision. The present study proposes a novel method for determining the collision frequency from the results of classical trajectory calculations. Classical trajectories for collisions of several polyatomic molecules (ethane, methane, tetrafluoromethane, and cyclohexane) with monatomic colliders (Ar, Kr, and Xe) were calculated on potential energy surfaces described by the third-order density-functional tight-binding method in combination with simple pairwise interaction potentials. Low-order (including non-integer-order) moments of the energy transferred in deactivating collisions were extracted from the trajectories and compared with those derived using some probability distribution models. The comparison demonstrates the inadequacy of the conventional Lennard-Jones collision model for representing the collision frequency and suggests a robust method for evaluating the collision frequency that is consistent with a given probability distribution model, such as the exponential-down model. The resulting collision frequencies for the exponential-down model are substantially higher than the Lennard-Jones collision frequencies and are close to the (hypothetical) capture rate constants for dispersion interactions. The practical adequacy of the exponential-down model is also briefly discussed.
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Affiliation(s)
- Akira Matsugi
- National Institute of Advanced Industrial Science and Technology (AIST) , 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
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13
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Matsugi A. Dissociation channels, collisional energy transfer, and multichannel coupling effects in the thermal decomposition of CH3F. Phys Chem Chem Phys 2018; 20:15128-15138. [DOI: 10.1039/c8cp02126k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The multichannel character of the thermal decomposition of CH3F and its dependency on the collisional energy transfer model are elucidated.
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Affiliation(s)
- Akira Matsugi
- National Institute of Advanced Industrial Science and Technology (AIST)
- Ibaraki 305-8569
- Japan
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14
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Ishizuka S, Matsugi A, Hama T, Enami S. Chain-propagation, chain-transfer, and hydride-abstraction by cyclic carbocations on water surfaces. Phys Chem Chem Phys 2018; 20:25256-25267. [DOI: 10.1039/c8cp04993a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
New mechanisms for the growth and increase in complexity of atmospheric aerosol particles are elucidated. The present findings will also be useful for interfacial polymer/oligomer synthesis.
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Affiliation(s)
| | - Akira Matsugi
- Research Institute of Science for Safety and Sustainability
- National Institute of Advanced Industrial Science and Technology
- Tsukuba 305-8569
- Japan
| | - Tetsuya Hama
- Institute of Low Temperature Science
- Hokkaido University
- Sapporo 060-0819
- Japan
| | - Shinichi Enami
- National Institute for Environmental Studies
- Tsukuba 305-8506
- Japan
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15
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Ishizuka S, Fujii T, Matsugi A, Sakamoto Y, Hama T, Enami S. Controlling factors of oligomerization at the water surface: why is isoprene such a unique VOC? Phys Chem Chem Phys 2018; 20:15400-15410. [DOI: 10.1039/c8cp01551a] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The interfacial oligomerization of isoprene is facilitated by the resonance stabilization through the formation of a tertiary carbocation with a conjugated CC bond pair, and electron enrichment induced by the neighboring methyl group.
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Affiliation(s)
- Shinnosuke Ishizuka
- Institute of Low Temperature Science
- Hokkaido University
- Sapporo 060-0819
- Japan
- National Institute for Environmental Studies
| | - Tomihide Fujii
- Graduate School of Global Environmental Studies
- Kyoto University
- Kyoto 606-8501
- Japan
| | - Akira Matsugi
- Research Institute of Science for Safety and Sustainability
- National Institute of Advanced Industrial Science and Technology
- Tsukuba 305-8569
- Japan
| | - Yosuke Sakamoto
- Graduate School of Global Environmental Studies
- Kyoto University
- Kyoto 606-8501
- Japan
- Graduate School of Human and Environmental Studies
| | - Tetsuya Hama
- Institute of Low Temperature Science
- Hokkaido University
- Sapporo 060-0819
- Japan
| | - Shinichi Enami
- National Institute for Environmental Studies
- Tsukuba 305-8506
- Japan
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16
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Abstract
The thermal decomposition reactions of 2,3,3,3- and trans-1,3,3,3-tetrafluoropropenes (TFPs) have been studied both experimentally and computationally to elucidate their kinetics and mechanism. The experiments were performed by observing the temporal profiles of HF produced in the decomposition of the tetrafluoropropenes behind shock waves at temperatures of 1540-1952 K (for 2,3,3,3-TFP) or 1525-1823 K (for trans-1,3,3,3-TFP) and pressure of 100-200 kPa in Ar bath. The reaction pathways responsible for the profiles were explored based on quantum chemical calculations. The decomposition of 2,3,3,3-TFP was predicted to proceed predominantly via direct 1,2-HF elimination to yield CHCCF3, while trans-1,3,3,3-TFP was found to decompose to HF and a variety of isomeric C3HF3 products including CHCCF3, CF2CCHF, CCHCF3, and CF2CHCF. The C3HF3 isomers can subsequently decompose to either CF2 + CHCF or CF2CC + HF products. Multichannel RRKM/master equation calculations were performed for the identified decomposition channels. The observed formation rates and apparent yields of HF are shown to be consistent with the computational predictions.
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Affiliation(s)
- Akira Matsugi
- National Institute of Advanced Industrial Science and Technology (AIST) , 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
| | - Kazuo Takahashi
- Department of Materials and Life Sciences, Sophia University , 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554, Japan
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17
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Affiliation(s)
- Akira Matsugi
- National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
| | - Hiroumi Shiina
- National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
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18
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Abstract
A fast and sensitive broadband absorption technique for measurements of high-temperature chemical kinetics and spectroscopy has been developed by applying broadband cavity-enhanced absorption spectroscopy (BBCEAS) in a shock tube. The developed method has effective absorption path lengths of 60-200 cm, or cavity enhancement factors of 12-40, over a wavelength range of 280-420 nm, and is capable of simultaneously recording absorption time profiles over an ∼32 nm spectral bandpass in a single experiment with temporal and spectral resolutions of 5 μs and 2 nm, respectively. The accuracy of the kinetic and spectroscopic measurements was examined by investigating high-temperature reactions and absorption spectra of formaldehyde behind reflected shock waves using 1,3,5-trioxane as a precursor. The rate constants obtained for the thermal decomposition reactions of 1,3,5-trioxane (to three formaldehyde molecules) and formaldehyde (to HCO + H) agreed well with the literature data. High-temperature absorption cross sections of formaldehyde between 280 and 410 nm have been determined at the post-reflected-shock temperatures of 955, 1265, and 1708 K. The results demonstrate the applicability of the BBCEAS technique to time- and wavelength-resolved sensitive absorption measurements at high temperatures.
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Affiliation(s)
- Akira Matsugi
- National Institute of Advanced Industrial Science and Technology (AIST) , 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
| | - Hiroumi Shiina
- National Institute of Advanced Industrial Science and Technology (AIST) , 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
| | - Tatsuo Oguchi
- Department of Environmental and Life Sciences, Toyohashi University of Technology , 1-1 Hibarigaoka, Tenpaku-cho, Toyohashi 441-8580, Japan
| | - Kazuo Takahashi
- Department of Materials and Life Sciences, Sophia University , 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554, Japan
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19
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Matsugi A. Collisional energy transfer in polyatomic molecules at high temperatures: Master equation analysis of vibrational relaxation of shock-heated alkanes. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2015.06.084] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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20
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Matsugi A. Dissociation of 1,1,1-Trifluoroethane Is an Intrinsic RRKM Process: Classical Trajectories and Successful Master Equation Modeling. J Phys Chem A 2015; 119:1846-58. [DOI: 10.1021/acs.jpca.5b00796] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Akira Matsugi
- National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
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21
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Affiliation(s)
- Akira Matsugi
- National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
| | - Kenji Yasunaga
- Department
of Applied Chemistry, National Defense Academy, Hashirimizu 1-10-20, Yokosuka, 239-8686, Japan
| | - Hiroumi Shiina
- National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
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22
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Matsugi A, Shiina H. Shock tube study on the thermal decomposition of fluoroethane using infrared laser absorption detection of hydrogen fluoride. J Phys Chem A 2014; 118:6832-7. [PMID: 25090102 DOI: 10.1021/jp5066709] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Motivated by recent shock tube studies on the thermal unimolecular decomposition of fluoroethanes, in which unusual trends have been reported for collisional energy-transfer parameters, the rate constants for the thermal decomposition of fluoroethane were investigated using a shock tube/laser absorption spectroscopy technique. The rate constants were measured behind reflected shock waves by monitoring the formation of HF by IR absorption at the R(1) transition in the fundamental vibrational band near 2476 nm using a distributed-feedback diode laser. The peak absorption cross sections of this absorption line have also been determined and parametrized using the Rautian-Sobel'man line shape function. The rate constant measurements covered a wide temperature range of 1018-1710 K at pressures from 100 to 290 kPa, and the derived rate constants were successfully reproduced by the master equation calculation with an average downward energy transfer, ⟨ΔEdown⟩, of 400 cm(-1).
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Affiliation(s)
- Akira Matsugi
- Research Institute of Science for Safety and Sustainability, National Institute of Advanced Industrial Science and Technology , 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
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23
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Affiliation(s)
- Akira Matsugi
- Research Institute of Science for Safety and Sustainability, National Institute of Advanced Industrial Science and Technology
| | - Hiroumi Shiina
- Research Institute of Science for Safety and Sustainability, National Institute of Advanced Industrial Science and Technology
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24
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Matsugi A, Uehara S, Kamata N, Mori N, Oku K, Mukai K, Nagano K. P694: Task dependency of long latency facilitatory effect on soleus H-reflex by cerebellar transcranial magnetic stimulation. Clin Neurophysiol 2014. [DOI: 10.1016/s1388-2457(14)50788-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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25
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Abstract
The reactivity is significantly enhanced by vibrational excitation of F2 whereas excitation of H2 vibration has a moderate effect.
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Affiliation(s)
- Akira Matsugi
- National Institute of Advanced Industrial Science and Technology (AIST)
- Tsukuba, Japan
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Abstract
Vibrationally excited species have been considered to play significant roles in H2/F2 reaction systems. In the present study, in order to obtain further understanding of the chain reaction mechanism in the combustion of mixtures containing H2 and F2, burning velocities for H2/F2/O2/N2 flames were measured and compared to that obtained from kinetic simulations using a detailed kinetic model, which involves the vibrationally excited species, HF(ν) and H2(ν), and the chain-branching reactions, HF(ν > 2) + F2 = HF + F + F (R1) and H2(ν = 1) + F2 = HF + H + F (R2). The results indicated that reaction R1 is not responsible for chain branching, whereas reaction R2 plays a dominant role in the chain reaction mechanism. The kinetic model reproduced the experimental burning velocities with the presumed rate constant of k2 = 6.6 × 10(-10) exp(-59 kJ mol(-1)/RT) cm(3) s(-1) for R2. The suggested chain-branching reaction was also investigated by quantum chemical calculations at the MRCI-F12+CV+Q/cc-pCVQZ-F12 level of theory.
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Affiliation(s)
- Akira Matsugi
- Research Institute of Science for Safety and Sustainability and ‡Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology , 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
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Abstract
Previous studies on the photodissociation of C2H5 reported rate constants for H-atom formation several orders of magnitude smaller than that predicted by Rice-Ramsperger-Kassel-Marcus (RRKM) theory. This Letter provides a potential explanation for this anomaly, based on direct trajectory calculations of C2H5 dissociation. The trajectories reveal the existence of a roaming dissociation channel that leads to the formation of C2H3 and H2. This channel is found to proceed over the ridge between the transition state of H-atom elimination and that of bimolecular H-abstraction. The formed C2H3 radical can subsequently dissociate to C2H2 and a H atom; this secondary dissociation is suggested to be a potential reason for the unexpectedly slow H-atom formation observed in the photodissociation experiments.
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Affiliation(s)
- Akira Matsugi
- National Institute of Advanced Industrial Science and Technology, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
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Affiliation(s)
- Akira Matsugi
- Department of Chemical System Engineering; School of Engineering, The University of Tokyo; 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan
- Research Institute of Science for Safety and Sustainability; National Institute of Advanced Industrial Science and Technology; 16-1 Onogawa Tsukuba Ibaraki 305-8569 Japan
| | - Akira Miyoshi
- Department of Chemical System Engineering; School of Engineering, The University of Tokyo; 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan
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Matsugi A, Miyoshi A. Reactions of o-benzyne with propargyl and benzyl radicals: potential sources of polycyclic aromatic hydrocarbons in combustion. Phys Chem Chem Phys 2012; 14:9722-8. [PMID: 22678346 DOI: 10.1039/c2cp41002h] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The kinetics and mechanisms of the reactions of o-benzyne with propargyl and benzyl radicals have been investigated computationally. The possible reaction pathways have been explored by quantum chemical calculations at the M06-2X/6-311+G(3df,2p)//B3LYP/6-311G(d,p) level and the mechanisms have been investigated by the Rice-Ramsperger-Kassel-Marcus theory/master-equation calculations. It was found that the o-benzyne associates with the propargyl and benzyl radicals without pronounced barriers and the activated adducts easily isomerize to five-membered ring species. Indenyl radical and fluorene + H were predicted to be dominantly produced by the reactions of o-benzyne with propargyl and benzyl radicals, respectively, with the rate constants close to the high-pressure limits at temperatures below 2000 K. The related reactions on the two potential energy surfaces, namely, the reaction between fulvenallenyl radical and acetylene and the decomposition reactions of indenyl and α-phenylbenzyl radicals were also investigated. The high reactivity of o-benzyne toward the resonance stabilized radicals suggested a potential role of o-benzyne as a precursor of polycyclic aromatic hydrocarbons in combustion.
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Affiliation(s)
- Akira Matsugi
- Department of Chemical System Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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Affiliation(s)
- Akira Matsugi
- Department of Chemical System Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kohsuke Suma
- Department of Chemical System Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Akira Miyoshi
- Department of Chemical System Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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Matsugi A, Suma K, Miyoshi A. Deuterium kinetic isotope effects on the gas-phase reactions of C2H with H2(D2) and CH4(CD4). Phys Chem Chem Phys 2011; 13:4022-31. [PMID: 21240398 DOI: 10.1039/c0cp02056g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Kinetics of the ethynyl (C(2)H) radical reactions with H(2), D(2), CH(4) and CD(4) was studied over the temperature range of 295-396 K by a pulsed laser photolysis/chemiluminescence technique. The C(2)H radicals were generated by ArF excimer-laser photolysis of C(2)H(2) or CF(3)C(2)H and were monitored by the chemiluminescence of CH(A(2)Δ) produced by their reaction with O(2) or O((3)P). The measured absolute rate constants for H(2) and CH(4) agreed well with the available literature data. The primary kinetic isotope effects (KIEs) were determined to be k(H(2))/k(D(2)) = 2.48 ± 0.14 and k(CH(4))/k(CD(4)) = 2.45 ± 0.16 at room temperature. Both of the KIEs increased as the temperature was lowered. The KIEs were analyzed by using the variational transition state theory with semiclassical small-curvature tunneling corrections. With anharmonic corrections on the loose transitional vibrational modes of the transition states, the theoretical predictions satisfactorily reproduced the experimental KIEs for both C(2)H + H(2)(D(2)) and C(2)H + CH(4)(CD(4)) reactions.
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Affiliation(s)
- Akira Matsugi
- Department of Chemical Systems Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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Affiliation(s)
- Akira Matsugi
- Department of Chemical System Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kohsuke Suma
- Department of Chemical System Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Akira Miyoshi
- Department of Chemical System Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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Nakajima M, Matsugi A, Miyoshi A. Mechanism and Kinetic Isotope Effect of the Reaction of C2(X1Σg+) Radicals with H2 and D2. J Phys Chem A 2009; 113:8963-70. [DOI: 10.1021/jp904165s] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Masakazu Nakajima
- Department of Chemical System Engineering, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Akira Matsugi
- Department of Chemical System Engineering, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Akira Miyoshi
- Department of Chemical System Engineering, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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