1
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Wang G, Liu T, Zou M, Karsili TNV, Lester MI. UV photodissociation dynamics of the acetone oxide Criegee intermediate: experiment and theory. Phys Chem Chem Phys 2023; 25:7453-7465. [PMID: 36848133 DOI: 10.1039/d3cp00207a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
The photodissociation dynamics of the dimethyl-substituted acetone oxide Criegee intermediate [(CH3)2COO] is characterized following electronic excitation to the bright 1ππ* state, which leads to O (1D) + acetone [(CH3)2CO, S0] products. The UV action spectrum of (CH3)2COO recorded with O (1D) detection under jet-cooled conditions is broad, unstructured, and essentially unchanged from the corresponding electronic absorption spectrum obtained using a UV-induced depletion method. This indicates that UV excitation of (CH3)2COO leads predominantly to the O (1D) product channel. A higher energy O (3P) + (CH3)2CO (T1) product channel is not observed, although it is energetically accessible. In addition, complementary MS-CASPT2 trajectory surface-hopping (TSH) simulations indicate minimal population leading to the O (3P) channel and non-unity overall probability for dissociation (within 100 fs). Velocity map imaging of the O (1D) products is utilized to reveal the total kinetic energy release (TKER) distribution upon photodissociation of (CH3)2COO at various UV excitation energies. Simulation of the TKER distributions is performed using a hybrid model that combines an impulsive model with a statistical component, the latter reflecting the longer-lived (>100 fs) trajectories identified in the TSH calculations. The impulsive model accounts for vibrational activation of (CH3)2CO arising from geometrical changes between the Criegee intermediate and the carbonyl product, indicating the importance of CO stretch, CCO bend, and CC stretch along with activation of hindered rotation and rock of the methyl groups in the (CH3)2CO product. Detailed comparison is also made with the TKER distribution arising from photodissociation dynamics of CH2OO upon UV excitation.
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Affiliation(s)
- Guanghan Wang
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
| | - Tianlin Liu
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
| | - Meijun Zou
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
| | - Tolga N V Karsili
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, LA 70504, USA.
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
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2
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Wang G, Liu T, Zou M, Sojdak CA, Kozlowski MC, Karsili TNV, Lester MI. Electronic Spectroscopy and Dissociation Dynamics of Vinyl-Substituted Criegee Intermediates: 2-Butenal Oxide and Comparison with Methyl Vinyl Ketone Oxide and Methacrolein Oxide Isomers. J Phys Chem A 2023; 127:203-215. [PMID: 36574960 DOI: 10.1021/acs.jpca.2c08025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The 2-butenal oxide Criegee intermediate [(CH3CH═CH)CHOO], an isomer of the four-carbon unsaturated Criegee intermediates derived from isoprene ozonolysis, is characterized on its first π* ← π electronic transition and by the resultant dissociation dynamics to O (1D) + 2-butenal [(CH3CH═CH)CHO] products. The electronic spectrum of 2-butenal oxide under jet-cooled conditions is observed to be broad and unstructured with peak absorption at 373 nm, spanning to half maxima at 320 and 420 nm, and in good accord with the computed vertical excitation energies and absorption spectra obtained for its lowest energy conformers. The distribution of total kinetic energy released to products is ascertained through velocity map imaging of the O (1D) products. About half of the available energy, deduced from the theoretically computed asymptotic energy, is accommodated as internal excitation of the 2-butenal fragment. A reduced impulsive model is introduced to interpret the photodissociation dynamics, which accounts for the geometric changes between 2-butenal oxide and the 2-butenal fragment, and vibrational activation of associated modes in the 2-butenal product. Application of the reduced impulsive model to the photodissociation of isomeric methyl vinyl ketone oxide reveals greater internal activation of the methyl vinyl ketone product arising from methyl internal rotation and rock, which is distinctly different from the dissociation dynamics of 2-butenal oxide or methacrolein oxide.
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Affiliation(s)
- Guanghan Wang
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Tianlin Liu
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Meijun Zou
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Christopher A Sojdak
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Marisa C Kozlowski
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Tolga N V Karsili
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, United States
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
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3
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Karsili TNV, Marchetti B, Lester MI, Ashfold MNR. Electronic Absorption Spectroscopy and Photochemistry of Criegee Intermediates. Photochem Photobiol 2023; 99:4-18. [PMID: 35713380 DOI: 10.1111/php.13665] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 06/14/2022] [Indexed: 01/26/2023]
Abstract
Interest in Criegee intermediates (CIs), often termed carbonyl oxides, and their role in tropospheric chemistry has grown massively since the demonstration of laboratory-based routes to their formation and characterization in the gas phase. This article reviews current knowledge regarding the electronic spectroscopy of atmospherically relevant CIs like CH2 OO, CH3 CHOO, (CH3 )2 COO and larger CIs like methyl vinyl ketone oxide and methacrolein oxide that are formed in the ozonolysis of isoprene, and of selected conjugated carbene-derived CIs of interest in the synthetic chemistry community. Of the aforementioned atmospherically relevant CIs, all except CH2 OO and (CH3 )2 COO exist in different conformers which, under tropospheric conditions, can display strikingly different thermal loss rates via unimolecular and bimolecular processes. Calculated photolysis rates based on their absorption properties suggest that solar photolysis will rarely be a significant contributor to the total loss rate for any CI under tropospheric conditions. Nonetheless, there is ever-growing interest in the absorption cross sections and primary photochemistry of CIs following excitation to the strongly absorbing 1 ππ* state, and how this varies with CI, with conformer and with excitation wavelength. The later part of this review surveys the photochemical data reported to date, including a range of studies that demonstrate prompt photo-induced fission of the terminal O-O bond, and speculates about possible alternate decay processes that could occur following non-adiabatic coupling to, and dissociation from, highly internally excited levels of the electronic ground state of a CI.
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Affiliation(s)
| | | | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA
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4
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Liu T, Zou M, Caracciolo A, Sojdak CA, Lester MI. Substituent Effects on the Electronic Spectroscopy of Four-Carbon Criegee Intermediates. J Phys Chem A 2022; 126:6734-6741. [DOI: 10.1021/acs.jpca.2c05502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tianlin Liu
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Meijun Zou
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Adriana Caracciolo
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Christopher A. Sojdak
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Marsha I. Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
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5
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Takahashi K. Wave Packet Calculation of Absolute UV Cross Section of Criegee Intermediates. J Phys Chem A 2022; 126:6080-6090. [PMID: 36041057 DOI: 10.1021/acs.jpca.2c04141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Criegee intermediates, R1R2COO, are reactive species formed in the atmosphere through the ozonolysis of alkenes. They have an intense ultraviolet (UV) adsorption between 300 to 400 nm. However, experimentally determining the absolute cross sections is not easy. We used wave packet propagation on an one-dimensional adiabatic potential energy curve (PEC) along the OO bond to simulate the UV spectra for various Criegee intermediates. Our results showed a very fast, ∼20 fs, decay out of the Franck-Condon region. This gives justification for using the semiclassical approach which was utilized in previous studies. From the comparison of various quantum chemistry methods, we found that multireference methods can give spectra with a width and cross section reproducing the experimental results, while single reference methods tend to give narrower skewed peaks with a larger cross section. From the test using wave packet propagation on various approximated PECs and transition moment functions, we show that the Gaussian approximation within the reflection method is valid. In addition, we found that we can obtain peak positions that reproduce the experimental results by shifting those obtained by MRCI+Q, CASSCF, EOMCCSD, and TDCAMB3LYP by -0.2, -1.0, -0.3, and -0.5 eV, respectively. The Gaussian approximation using peak position, oscillator strength, and peak width from MRCI+Q is a cost-effective way to simulate the UV spectra of Crigee intermediates for which experimental determination may be hard.
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Affiliation(s)
- Kaito Takahashi
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
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6
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Nikoobakht B, Köppel H. Correlated quantum treatment of the photodissociation dynamics of formaldehyde oxide CH 2OO. Phys Chem Chem Phys 2022; 24:12433-12441. [PMID: 35575032 DOI: 10.1039/d2cp01007k] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An extended theoretical analysis of the photodissociation of the smallest Criegee intermediate CH2OO following excitation to the B state is presented. It relies on explicitly correlated multireference electronic wavefunctions combined with a quantum dynamical treatment for two interacting (B-C) electronic states and three coupled nuclear degrees of freedom. The 3D model relies on PESs along the O-O and C-O stretching as well as C-O-O bending modes for the two lowest excited states with A' symmetry, and is sufficiently accurate to reproduce the experimental B1A'-X1A' absorption spectrum, especially at the low-energy range to unprecedented accuracy. The existence of a deep well (∼0.4 eV) on the (diabatic) B state causes a considerable amount of the wavepacket to be reflected by the B state well, which can explain the vibronic structures appearing in the long wavelength range of 360-470 nm of the spectrum. The main progression appearing in the energy range from 360 to 470 nm is assigned to the O-O stretching mode while finer details are affected by couplings to the C-O stretching and C-O-O bending modes. The weakly avoided crossing between the B-state and C-state potential energy surfaces appearing near 3.1 eV excitation energy (for RS2-F12 method) causes considerable disturbance in the vibronic fine structure of the bands. The description of the latter is quite strongly affected by the type of electron correlation treatment adopted, either fully variational (MRCI type) or perturbation theoretic (RS2 type). The results give novel insight into the complex interactions governing that intriguing process.
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Affiliation(s)
- Behnam Nikoobakht
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, INF 229, D-69120 Heidelberg, Germany.
| | - Horst Köppel
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, INF 229, D-69120 Heidelberg, Germany.
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7
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Lin YH, Takahashi K, Lin JJM. Absolute photodissociation cross sections of thermalized methyl vinyl ketone oxide and methacrolein oxide. Phys Chem Chem Phys 2022; 24:10439-10450. [PMID: 35441630 DOI: 10.1039/d2cp00476c] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Methyl vinyl ketone oxide (MVKO) and methacrolein oxide (MACRO) are resonance-stabilized Criegee intermediates which are formed in the ozonolysis reaction of isoprene, the most abundant unsaturated hydrocarbon in the atmosphere. The absolute photodissociation cross sections of MVKO and MACRO were determined by measuring their laser depletion fraction at 352 nm, which was deduced from their time-resolved UV-visible absorption spectra. After calibrating the 352 nm laser fluence with the photodissociation of NO2, for which the absorption cross section and photodissociation quantum yield are well known, the photodissociation cross sections of thermalized (299 K) MVKO and MACRO at 352 nm were determined to be (3.02 ± 0.60) × 10-17 cm2 and (1.53 ± 0.29) × 10-17 cm2, respectively. Using their reported spectra and photodissociation quantum yields, their peak absorption cross sections were deduced to be (3.70 ± 0.74) × 10-17 cm2 (at 371 nm, MVKO) and (3.04 ± 0.58) × 10-17 cm2 (at 397 nm, MACRO). These values agree fairly with our theoretical predictions and are substantially larger than those of smaller, alkyl-substituted Criegee intermediates (CH2OO, syn-CH3CHOO, (CH3)2COO), revealing the effect of extended conjugation. With their cross sections, we also quantified the synthesis yields of MVKO and MACRO in the present experiment to be 0.22 ± 0.10 (at 299 K and 30-700 torr) and 0.043 ± 0.019 (at 299 K and 500 torr), respectively, relative to their photolyzed precursors. The lower yield of MACRO can be related to the high endothermicity of its formation channel.
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Affiliation(s)
- Yen-Hsiu Lin
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan. .,Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Kaito Takahashi
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
| | - Jim Jr-Min Lin
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan. .,Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
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8
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Esposito VJ, Werba O, Bush SA, Marchetti B, Karsili TNV. Insights into the Ultrafast Dynamics of CH 2 OO and CH 3 CHOO Following Excitation to the Bright 1 ππ* State: The Role of Singlet and Triplet States. Photochem Photobiol 2021; 98:763-772. [PMID: 34767632 DOI: 10.1111/php.13560] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 11/09/2021] [Indexed: 12/11/2022]
Abstract
Criegee intermediates make up a class of molecules that are of significant atmospheric importance. Understanding their electronically excited states guides experimental detection and provides insight into whether solar photolysis plays a role in their removal from the troposphere. The latter is particularly important for large and functionalized Criegee intermediates. In this study, the excited state chemistry of two small Criegee intermediates, formaldehyde oxide (CH2 OO) and acetaldehyde oxide (CH3 CHOO), was modeled to compare their specific dynamics and mechanisms following excitation to the bright ππ* state and to assess the involvement of triplet states to the excited state decay process. Following excitation to the bright ππ* state, the photoexcited population exclusively evolves to form oxygen plus aldehyde products without the involvement of triplet states. This occurs despite the presence of a more thermodynamically stable triplet path and several singlet/triplet energy crossings at the Franck-Condon geometry and contrasts with the photodynamics of related systems such as acetaldehyde and acetone. This work sets the foundations to study Criegee intermediates with greater molecular complexity, wherein a bathochromic shift in the electron absorption profiles may ensure greater removal via solar photolysis.
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Affiliation(s)
| | | | - Sarah A Bush
- University of Louisiana at Lafayette, Lafayette, LA
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9
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Wang G, Liu T, Caracciolo A, Vansco MF, Trongsiriwat N, Walsh PJ, Marchetti B, Karsili TNV, Lester MI. Photodissociation dynamics of methyl vinyl ketone oxide: A four-carbon unsaturated Criegee intermediate from isoprene ozonolysis. J Chem Phys 2021; 155:174305. [PMID: 34742186 DOI: 10.1063/5.0068664] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The electronic spectrum of methyl vinyl ketone oxide (MVK-oxide), a four-carbon Criegee intermediate derived from isoprene ozonolysis, is examined on its second π* ← π transition, involving primarily the vinyl group, at UV wavelengths (λ) below 300 nm. A broad and unstructured spectrum is obtained by a UV-induced ground state depletion method with photoionization detection on the parent mass (m/z 86). Electronic excitation of MVK-oxide results in dissociation to O (1D) products that are characterized using velocity map imaging. Electronic excitation of MVK-oxide on the first π* ← π transition associated primarily with the carbonyl oxide group at λ > 300 nm results in a prompt dissociation and yields broad total kinetic energy release (TKER) and anisotropic angular distributions for the O (1D) + methyl vinyl ketone products. By contrast, electronic excitation at λ ≤ 300 nm results in bimodal TKER and angular distributions, indicating two distinct dissociation pathways to O (1D) products. One pathway is analogous to that at λ > 300 nm, while the second pathway results in very low TKER and isotropic angular distributions indicative of internal conversion to the ground electronic state and statistical unimolecular dissociation.
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Affiliation(s)
- Guanghan Wang
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Tianlin Liu
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Adriana Caracciolo
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Michael F Vansco
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Nisalak Trongsiriwat
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Patrick J Walsh
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Barbara Marchetti
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, USA
| | - Tolga N V Karsili
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, USA
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
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10
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Esposito VJ, Liu T, Wang G, Caracciolo A, Vansco MF, Marchetti B, Karsili TNV, Lester MI. Photodissociation Dynamics of CH 2OO on Multiple Potential Energy Surfaces: Experiment and Theory. J Phys Chem A 2021; 125:6571-6579. [PMID: 34314179 DOI: 10.1021/acs.jpca.1c03643] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
UV excitation of the CH2OO Criegee intermediate across most of the broad span of the (B 1A')-(X 1A') spectrum results in prompt dissociation to two energetically accessible asymptotes: O (1D) + H2CO (X 1A1) and O (3P) + H2CO (a 3A''). Dissociation proceeds on multiple singlet potential energy surfaces that are coupled by two regions of conical intersection (CoIn). Velocity map imaging (VMI) studies reveal a bimodal total kinetic energy release (TKER) distribution for the O (1D) + H2CO (X 1A1) products with the major and minor components accounting for ca. 40% and ca. 20% on average of the available energy (Eavl), respectively. The unexpected low TKER component corresponds to highly internally excited H2CO (X 1A1) products accommodating ca. 80% of Eavl. Full dimensional trajectory calculations suggest that the bimodal TKER distribution of the O (1D) + H2CO (X 1A1) products originates from two different dynamical pathways: a primary pathway (69%) evolving through one CoIn region to products and a smaller component (20%) sampling both CoIn regions enroute to products. Those that access both CoIn regions likely give rise to the more highly internally excited H2CO (X 1A1) products. The remaining trajectories (11%) dissociate to O (3P) + H2CO (a 3A'') products after traversing through both CoIn regions. The complementary experimental and theoretical investigation provides insight on the photodissociation of CH2OO via multiple dissociation pathways through two regions of CoIn that control the branching and energy distributions of products.
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Affiliation(s)
- Vincent J Esposito
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Tianlin Liu
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Guanghan Wang
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Adriana Caracciolo
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Michael F Vansco
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Barbara Marchetti
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, United States
| | - Tolga N V Karsili
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, United States
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
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11
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Nikoobakht B, Köppel H. UV absorption spectrum and photodissociation dynamics of CH 2OO following excitation to the B1 A′ state. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1958019] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Behnam Nikoobakht
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Heidelberg, Germany
| | - Horst Köppel
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Heidelberg, Germany
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12
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McCoy JC, Marchetti B, Thodika M, Karsili TNV. A Simple and Efficient Method for Simulating the Electronic Absorption Spectra of Criegee Intermediates: Benchmarking on CH 2OO and CH 3CHOO. J Phys Chem A 2021; 125:4089-4097. [PMID: 33970629 DOI: 10.1021/acs.jpca.1c01074] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Criegee intermediates (CIs) play a vital role in the atmosphere-known most prominently for enhancing the oxidizing capacity of the troposphere. Knowledge of their electronic absorption spectra is of vital importance for two reasons: (1) to aid experimentalists in detecting CIs and (2) in deciding if their removal is affected by solar photolysis. In this article we report a simple and efficient method based on the nuclear ensemble method that may be effectively used to compute the electronic absorption spectra of Criegee intermediates without the need for extensive computation of preparing the initial configurations of the starting geometry. We use this method to benchmark several excited-state electronic structure methods and their efficacy in reproducing the electronic absorption spectra of two well-known cases of CI: CH2OO and CH3CHOO. The success and computational feasibility of the methodology are crucial for its applicability to CIs of increasing molecular complexity, which have no known experimentally measured electronic absorption spectra, allowing a guide for experimentalists. Application of the methodology to more complex CIs (e.g., those with extended conjugation or those derived from endocyclic alkenes) will also reveal if solar photolysis becomes a competitive removal process when compared to unimolecular decay or bimolecular chemistry.
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Affiliation(s)
- Julia C McCoy
- University of Louisiana at Lafayette, Lafayette, Louisiana 70503, United States
| | - Barbara Marchetti
- University of Louisiana at Lafayette, Lafayette, Louisiana 70503, United States
| | - Mushir Thodika
- Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Tolga N V Karsili
- University of Louisiana at Lafayette, Lafayette, Louisiana 70503, United States
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13
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Vansco MF, Marchetti B, Trongsiriwat N, Bhagde T, Wang G, Walsh PJ, Klippenstein SJ, Lester MI. Synthesis, Electronic Spectroscopy, and Photochemistry of Methacrolein Oxide: A Four-Carbon Unsaturated Criegee Intermediate from Isoprene Ozonolysis. J Am Chem Soc 2019; 141:15058-15069. [PMID: 31446755 DOI: 10.1021/jacs.9b05193] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Ozonolysis of isoprene, one of the most abundant volatile organic compounds in the earth's atmosphere, generates the four-carbon unsaturated methacrolein oxide (MACR-oxide) Criegee intermediate. The first laboratory synthesis and direct detection of MACR-oxide is achieved through reaction of photolytically generated, resonance-stabilized iodoalkene radicals with oxygen. MACR-oxide is characterized on its first π* ← π electronic transition using a ground-state depletion method. MACR-oxide exhibits a broad UV-visible spectrum peaked at 380 nm with weak oscillatory structure at long wavelengths ascribed to vibrational resonances. Complementary theory predicts two strong π* ← π transitions arising from extended conjugation across MACR-oxide with overlapping contributions from its four conformers. Electronic promotion to the 11ππ* state agrees well with experiment, and results in nonadiabatic coupling and prompt release of O 1D products observed as anisotropic velocity-map images. This UV-visible detection scheme will enable study of its unimolecular and bimolecular reactions under thermal conditions of relevance to the atmosphere.
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Affiliation(s)
- Michael F Vansco
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
| | - Barbara Marchetti
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
| | - Nisalak Trongsiriwat
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
| | - Trisha Bhagde
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
| | - Guanghan Wang
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
| | - Patrick J Walsh
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division , Argonne National Laboratory , Lemont , Illinois 60439 , United States
| | - Marsha I Lester
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
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14
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Vansco MF, Marchetti B, Lester MI. Electronic spectroscopy of methyl vinyl ketone oxide: A four-carbon unsaturated Criegee intermediate from isoprene ozonolysis. J Chem Phys 2019; 149:244309. [PMID: 30599734 DOI: 10.1063/1.5064716] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Ozonolysis of isoprene, one of the most abundant volatile organic compounds in the atmosphere, proceeds through methyl vinyl ketone oxide (MVK-oxide), methacrolein oxide, and formaldehyde oxide (CH2OO) Criegee intermediates. The present study focuses on MVK-oxide, a four-carbon unsaturated carbonyl oxide intermediate, using vacuum ultraviolet photoionization at 118 nm and UV-visible induced depletion of the m/z = 86 mass channel to characterize its first π* ← π electronic transition. The electronic spectrum is broad and unstructured with its peak at 388 nm (3.2 eV). The MVK-oxide spectrum is shifted to a significantly longer wavelength than CH2OO and alkyl-substituted Criegee intermediates studied previously due to extended conjugation across the vinyl and carbonyl oxide groups. Electronic excitation results in rapid dissociation at λ ≤ 430 nm to methyl vinyl ketone and O 1D products, the latter detected by 2 + 1 resonance enhanced multiphoton ionization using velocity map imaging. Complementary electronic structure calculations (CASPT2(12,10)/AVDZ) predict two π* ← π transitions with significant oscillator strength for each of the four conformers of MVK-oxide with vertical excitation energies (and corresponding wavelengths) in the 3.1-3.6 eV (350-400 nm) and 4.5-5.5 eV (220-280 nm) regions. The computed electronic absorption profile of MVK-oxide, based on a Wigner distribution of ground state configurations and summed over the four conformers, is predicted to peak at 397 nm. UV-visible spectroscopy on the first π* ← π transition is shown by a combination of experiment and theory to provide a sensitive method for detection of the MVK-oxide Criegee intermediate that will enable further studies of its photochemistry and unimolecular and bimolecular reaction dynamics.
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Affiliation(s)
- Michael F Vansco
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Barbara Marchetti
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
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15
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Chang YP, Li YL, Liu ML, Ou TC, Lin JJM. Absolute Infrared Absorption Cross Section of the Simplest Criegee Intermediate Near 1285.7 cm -1. J Phys Chem A 2018; 122:8874-8881. [PMID: 30351942 DOI: 10.1021/acs.jpca.8b06759] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The ν4 fundamental of the simplest Criegee intermediate, CH2OO, has been monitored with high-resolution infrared (IR) transient absorption spectroscopy under total pressures of 4-94 Torr. This IR spectrum provides an unambiguous identification of CH2OO and is potentially useful to determine the number density of CH2OO in various laboratory studies. Here we utilized an ultraviolet (UV) and IR coupled spectrometer to measure the UV and IR absorption spectra of CH2OO simultaneously; the absolute IR cross section can then be determined by using a known UV cross section. Due to significant pressure broadening in the studied pressure range, we integrated the IR absorption spectra between 1285.2 and 1286.4 cm-1 (covering the Q branch), and then we converted this integrated absorbance to the absolute integral IR cross section of CH2OO (for the Q branch); its absolute value is (3.7 ± 0.6) × 10-19 cm·molecule-1 or 2.2 ± 0.4 km·mol-1. The whole rotational band (P, Q, and R branches) can be adequately simulated by using the precise spectroscopic parameters from the literature, yielding the absolute integral IR cross section (full ν4 band) to be 19.2 ± 3.5 km·mol-1. For a practical detection of CH2OO, this work also reports the peak cross section as a function of total pressure (4-94 Torr O2). At low pressure (≤4 Torr), where the pressure broadening is insignificant, the absorption cross section of the highest peak is (6.2 ± 0.9) × 10-18 cm2·molecule-1 (at the system line width of 0.004 cm-1 fwhm).
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Affiliation(s)
- Yuan-Pin Chang
- Department of Chemistry , National Sun Yat-sen University , Kaohsiung 80424 , Taiwan
| | - Yu-Lin Li
- Institute of Atomic and Molecular Sciences , Academia Sinica , Taipei 10617 , Taiwan.,Department of Chemistry , National Taiwan University , Taipei 10617 , Taiwan
| | - Meng-Ling Liu
- Institute of Atomic and Molecular Sciences , Academia Sinica , Taipei 10617 , Taiwan.,Air Quality Control, Solid Waste and Waste Water Process Engineering , Universität Stuttgart , Stuttgart 70569 , Germany
| | - Ting-Chun Ou
- Institute of Atomic and Molecular Sciences , Academia Sinica , Taipei 10617 , Taiwan
| | - Jim Jr-Min Lin
- Institute of Atomic and Molecular Sciences , Academia Sinica , Taipei 10617 , Taiwan.,Department of Chemistry , National Taiwan University , Taipei 10617 , Taiwan
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16
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Jr-Min Lin J, Chao W. Structure-dependent reactivity of Criegee intermediates studied with spectroscopic methods. Chem Soc Rev 2018; 46:7483-7497. [PMID: 28840926 DOI: 10.1039/c7cs00336f] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Criegee intermediates are very reactive carbonyl oxides that are formed in reactions of unsaturated hydrocarbons with ozone (ozonolysis). Recently, Criegee intermediates have gained significant attention since a new preparation method has been reported in 2012, which employs the reaction of iodoalkyl radical with molecular oxygen: for instance, CH2I + O2 → CH2OO + I. This new synthesis route can produce Criegee intermediates with a high number density, which allows direct detection of the Criegee intermediate via various spectroscopic tools, including vacuum UV photoionization mass spectrometry, absorption and action spectroscopy in the UV and IR regions, and microwave spectroscopy. Criegee intermediates have been thought to play important roles in atmospheric chemistry, such as in OH radical formation as well as oxidation of atmospheric gases such as SO2, NO2, volatile organic compounds, organic and inorganic acids, and even water. These reactions are relevant to acid rain and aerosol formation. Kinetics data including rate coefficients, product yields and their temperature and pressure dependences are important for understanding and modeling relevant atmospheric chemistry. In fundamental physical chemistry, Criegee intermediates have unique and interesting features, which have been partially revealed through spectroscopic, kinetic, and dynamic investigations. Although previous review articles have discussed Criegee intermediates, new data and knowledge on Criegee intermediates are still being accumulated. In this tutorial review, we have focused on structure-dependent reactivity of Criegee intermediates and various spectroscopic tools that have been utilized to probe the kinetics of Criegee intermediates.
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Affiliation(s)
- Jim Jr-Min Lin
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
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17
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Yin C, Takahashi K. How big is the substituent dependence of the solar photolysis rate of Criegee intermediates? Phys Chem Chem Phys 2018; 20:16247-16255. [DOI: 10.1039/c8cp02015a] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Substituent dependence of the UV spectra of Criegee intermediates were calculated using multireference methods.
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Affiliation(s)
- Cangtao Yin
- Institute of Atomic and Molecular Sciences
- Academia Sinica
- Taipei 10617
- Taiwan
| | - Kaito Takahashi
- Institute of Atomic and Molecular Sciences
- Academia Sinica
- Taipei 10617
- Taiwan
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18
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Trabelsi T, Kumar M, Francisco JS. Substituent effects on the spectroscopic properties of Criegee intermediates. J Chem Phys 2017; 147:164303. [DOI: 10.1063/1.4998170] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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