Dynamics of reactions O(D1)+C6H6 and C6D6

Chen, Hui Fen; Liang, Chi Wei; Lin, Jim J.; Lee, Yuan‐Pern; Ogilvie, J. F.; Xu, Z. F.; Lin, Ming‐Chang

doi:10.1063/1.2994734

Cited by 9 publications

(27 citation statements)

References 85 publications

(101 reference statements)

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“…It should be noted that dissociation of C 6 H 5 O to C 5 H 5 + CO is energetically not possible for O( 3 P) because of a high barrier of ca. 50 kcal/mol (see Figure ) and negligible also for O( 1 D) . Furthermore, we note that previous CMB work on the reactions of both O( 3 P) and O( 1 D) with benzene has shown that some phenol adduct survives until the detector for the O( 3 P) reaction but not for the O( 1 D) reaction .…”

Section: Resultsmentioning

confidence: 58%

“…The resulting collision energy was 8.2 kcal/mol. The small percentage of O( 1 D) present in the atomic oxygen beam was expected to contribute significantly to the measured product distributions because the reaction cross section of O( 3 P) with benzene is considerably lower than that of O( 1 D), as the O( 3 P) + C 6 H 6 reaction is characterized by a very significant entrance energy barrier of about 4 kcal/mol while the O( 1 D) reaction is barrierless …”

Section: Methodsmentioning

confidence: 99%

“…On the basis of the theoretical part of the present work, which supersedes previous theoretical studies, , the energetically available reactive channels for the O( 3 P, 1 D) + benzene reactions are the following: The reported enthalpies of reaction at 0 K are those calculated in this work (the values in parentheses are experimental values from recommended Δ H 0 0 ); C 5 H 6 stands for 1,3-cyclopentadiene and C 5 H 5 for the cyclopentadienyl radical. It should be noted that the H abstraction channel leading to OH + C 6 H 5 (phenyl) is endoergic by about 10 kcal/mol for O( 3 P) and exhibits a high energy barrier (of about 12 kcal/mol); therefore, it is expected to contribute negligibly to the O( 3 P) reaction and to be minor also for the O( 1 D) reaction (see the SI).…”

Section: Introductionmentioning

confidence: 99%

“…The reactants and the main observed products (phenoxy + H, cyclopentadiene + CO, and cyclopentadienyl + H + CO, are indicated in black. The abstraction channel leading to OH + C 6 H 5 (phenyl), which is endothermic for O( 3 P) by about 12 kcal/mol (see ref ) and exothermic for O( 1 D) by about 36 kcal/mol (see ref and the SI), the pathway from 3 W1(A″) to phenoxy + H, which has a high transition state energy of about 16 kcal/mol with respect to reactants (see ref ), and the pathway to C 6 H 4 (benzyne) + H 2 O products (Δ H 0 0 = −26.5 kcal/mol; see ref ), which have very low probabilities of formation, are not shown.…”

Section: Introductionmentioning

confidence: 99%

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Crossed-Beam and Theoretical Studies of the O(³P, ¹D) + Benzene Reactions: Primary Products, Branching Fractions, and Role of Intersystem Crossing

et al. 2021

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Reliable modeling of hydrocarbon oxidation relies critically on knowledge of the branching fractions (BFs) as a function of temperature ( T ) and pressure ( p ) for the products of the reaction of the hydrocarbon with atomic oxygen in its ground state, O( 3 P). During the past decade, we have performed in-depth investigations of the reactions of O( 3 P) with a variety of small unsaturated hydrocarbons using the crossed molecular beam (CMB) technique with universal mass spectrometric (MS) detection and time-of-flight (TOF) analysis, combined with synergistic theoretical calculations of the relevant potential energy surfaces (PESs) and statistical computations of product BFs, including intersystem crossing (ISC). This has allowed us to determine the primary products, their BFs, and extent of ISC to ultimately provide theoretical channel-specific rate constants as a function of T and p . In this work, we have extended this approach to the oxidation of one of the most important species involved in the combustion of aromatics: the benzene (C 6 H 6 ) molecule. Despite extensive experimental and theoretical studies on the kinetics and dynamics of the O( 3 P) + C 6 H 6 reaction, the relative importance of the C 6 H 5 O (phenoxy) + H open-shell products and of the spin-forbidden C 5 H 6 (cyclopentadiene) + CO and phenol adduct closed-shell products are still open issues, which have hampered the development of reliable benzene combustion models. With the CMB technique, we have investigated the reaction dynamics of O( 3 P) + benzene at a collision energy ( E c ) of 8.2 kcal/mol, focusing on the occurrence of the phenoxy + H and spin-forbidden C 5 H 6 + CO and phenol channels in order to shed further light on the dynamics of this complex and important reaction, including the role of ISC. Concurrently, we have also investigated the reaction dynamics of O( 1 D) + benzene at the same E c . Synergistic high-level electronic structure calculations of the underlying triplet/singlet PESs, including nonadiabatic couplings, have been performed to complement and assist the interpretation of the experimental results. Statistical (RRKM)/master equation (ME) computations of the product distribution and BFs on these PESs, with inclusion of ISC, have been performed and compared to experiment. In light of the reasonable agreement between the CMB experiment, literature kinetic experimental results, and theoretical predictions for the O( 3 P) + benzene reaction, the so-validated computatio...

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Section: Resultsmentioning

confidence: 58%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Crossed-Beam and Theoretical Studies of the O(³P, ¹D) + Benzene Reactions: Primary Products, Branching Fractions, and Role of Intersystem Crossing

et al. 2021

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“…As can be seen, the m / z = 66 angular distribution exhibits a prominent peak, centered at the CM angle, superimposed to two broad wings. The central peak reflects the small amount of phenol adduct from the O( 3 P) reaction (no phenol was observed from the O( 1 D) reaction , ) that fragments in the ionizer to C 5 H 6 + , and its distribution reflects the centroid distribution (see the Supporting Information). In contrast, the two side wings reflect the formation of the C 5 H 6 product detected at its parent mass (66 amu) from both O( 3 P) and O( 1 D) reactions (see the Supporting Information).…”

mentioning

confidence: 99%

Theoretical Study of the Extent of Intersystem Crossing in the O(³P) + C₆H₆ Reaction with Experimental Validation

Cavallotti

Falco

Maffei

et al. 2020

J. Phys. Chem. Lett.

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The extent of intersystem crossing in the O( 3 P) + C 6 H 6 reaction, a prototypical system for spin-forbidden reactions in oxygenated aromatic molecules, is theoretically evaluated for the first time. Calculations are performed using nonadiabatic transition-state theory coupled with stochastic master equation simulations and Landau–Zener theory. It is found that the dominant intersystem crossing pathways connect the T2 and S0 potential energy surfaces through at least two distinct minimum-energy crossing points. The calculated channel-specific rate constants and intersystem crossing branching fractions differ from previous literature estimates and provide valuable kinetic data for the investigation of benzene and polycyclic aromatic hydrocarbons oxidation in interstellar, atmospheric, and combustion conditions. The theoretical results are supported by crossed molecular beam experiments with electron ionization mass-spectrometric detection and time-of-flight analysis at 8.2 kcal/mol collision energy. This system is a suitable benchmark for theoretical and experimental studies of intersystem crossing in aromatic species.

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Transient Infrared Absorption Spectra of Reaction Intermediates Detected with a Step‐scan Fourier‐transform Infrared Spectrometer

Huang

Chen

Hsu

et al. 2013

J Chinese Chemical Soc

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Our group has utilized a step-scan FTIR spectrometer operating in the absorption mode to characterize transient species in chemical reactions upon photo-irradiation of gaseous mixtures in a multipass White cell. The operational temporal resolution is typically 1-10 ms with spectral resolution 0.1-4 cm -1 , depending on conditions. The acquisition of both ac-and dc-coupled signals enables an extraction of minute changes in the large background signal to attain a typical detectable absorbance variation greater than 11 0 -4 . By consideration of reaction mechanisms and comparison of vibrational wavenumbers, IR intensities, and rotational contours predicted with theoretical calculations, we have assigned IR absorption bands of many important atmospheric free radicals and unstable species including their conformers, such as ClCO, ClSO, ClCS, ClCOOH, CH 3 SO 2 , CH 3 SOO, CH 3 OSO, CH 3 SO, CH 3 OO, CH 3 C(O)OO, CH 2 OO C 6 H 5 CO, C 6 H 5 SO 2 , and C 6 H 5 C(O)OO. The advantages and limitations of this technique to perform spectral and kinetic investigations of transient species in chemical reactions are discussed. (2010-). His main research interests focus on the spectroscopy, kinetics, and ion pumps of the photosynthetic proteins, using various time-resolved approaches including step-scan FTIR, nanosecond-resolved transient absorption, and electrochemical methods. Chiao Tung University. The main research topics pursued concern spectroscopy, kinetics and dynamics of free radicals or unstable species, using diverse methods including step-scan time-resolved FTIR (emission or absorption), matrix isolation using p-H 2 , cavity ringdown, IR-VUV photoionization, and ultrafast lasers. He has identified more than 70 new free radicals, most of which are important in atmospheric, combustion, or planetary chemistry. He has received numerous honors, and was elected asThe step-scan measurements are performed under the master mode of the spectrometer (Thermo Nicolet, NEXUS 870), in which the timing trigger is initiated by the spectrometer. Figure 3 CHEMICAL SOCIETY Fig. 5. Schematic of the White cell. The first and second IR beam paths and the first and second UV photolysis beam paths of the multiply reflected light are shown. Circular dots indicate images of the IR beam at each reflection.

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Dynamics of reactions O(D1)+C6H6 and C6D6

Cited by 9 publications

References 85 publications

Crossed-Beam and Theoretical Studies of the O(³P, ¹D) + Benzene Reactions: Primary Products, Branching Fractions, and Role of Intersystem Crossing

Crossed-Beam and Theoretical Studies of the O(³P, ¹D) + Benzene Reactions: Primary Products, Branching Fractions, and Role of Intersystem Crossing

Theoretical Study of the Extent of Intersystem Crossing in the O(³P) + C₆H₆ Reaction with Experimental Validation

Transient Infrared Absorption Spectra of Reaction Intermediates Detected with a Step‐scan Fourier‐transform Infrared Spectrometer

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Dynamics of reactions O(D1)+C6H6 and C6D6

Cited by 9 publications

References 85 publications

Crossed-Beam and Theoretical Studies of the O(3P, 1D) + Benzene Reactions: Primary Products, Branching Fractions, and Role of Intersystem Crossing

Crossed-Beam and Theoretical Studies of the O(3P, 1D) + Benzene Reactions: Primary Products, Branching Fractions, and Role of Intersystem Crossing

Theoretical Study of the Extent of Intersystem Crossing in the O(3P) + C6H6 Reaction with Experimental Validation

Transient Infrared Absorption Spectra of Reaction Intermediates Detected with a Step‐scan Fourier‐transform Infrared Spectrometer

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Product

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Crossed-Beam and Theoretical Studies of the O(³P, ¹D) + Benzene Reactions: Primary Products, Branching Fractions, and Role of Intersystem Crossing

Crossed-Beam and Theoretical Studies of the O(³P, ¹D) + Benzene Reactions: Primary Products, Branching Fractions, and Role of Intersystem Crossing

Theoretical Study of the Extent of Intersystem Crossing in the O(³P) + C₆H₆ Reaction with Experimental Validation