1
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Balaganesh M, Song J, Kasai T, Lin KC. Photodissociation of CH 2BrCHBrC(O)Cl at 248 nm: probing Br 2 as the primary fragment using cavity ring-down spectroscopy. Phys Chem Chem Phys 2021; 23:22492-22500. [PMID: 34590099 DOI: 10.1039/d1cp02279b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photodissociation of 2,3-dibromopropionyl chloride (CH2BrCHBrC(O)Cl, 2,3-DBPC) at 248 nm was carried out to study Br2 as the primary molecular product in the B3Π+0u ← X1Σ+g transition using cavity ring-down absorption spectroscopy. The rotational spectra (v'' = 0-2) were acquired and assigned with the aid of spectral simulation. It is verified that the obtained Br2 fragment is attributed to the one-photon dissociation of 2,3-DBPC and is free from contributions of secondary reactions. The vibrational ratio of the Br2 population of v(0):v(1):v(2) is equal to 1:(0.58 ± 0.12):(0.23 ± 0.09), corresponding to the Boltzmann vibrational temperature of 623 ± 38 K. The quantum yield of Br2 eliminated from 2,3-DBPC is estimated to be 0.09 ± 0.04. The dissociation pathways of 2,3-DBPC and its potential energy surfaces were calculated using density functional theory. By employing the CCSD(T)//M062X/6-31+g(d,p) level of theory, transition state barriers and corresponding reaction energies were calculated for the Br, Cl, Br2, BrCl, HBr and HCl elimination channels. The unimolecular rate constant for Br2 elimination was determined to be 2.09 × 105 s-1 using Rice-Ramsperger-Kassel-Marcus (RRKM) theory, thus explaining the small quantum yield of the Br2 channel.
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Affiliation(s)
- Muthiah Balaganesh
- Department of Chemistry, National Taiwan Univeristy, Taipei 106, Taiwan.
| | - Joseph Song
- Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, New York 11794-3400, USA
| | - Toshio Kasai
- Department of Chemistry, National Taiwan Univeristy, Taipei 106, Taiwan. .,Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
| | - King-Chuen Lin
- Department of Chemistry, National Taiwan Univeristy, Taipei 106, Taiwan. .,Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
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2
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Muthiah B, Kasai T, Lin KC. Probing BrCl from photodissociation of CH 2BrCl and CHBr 2Cl at 248 nm using cavity ring-down spectroscopy. Phys Chem Chem Phys 2021; 23:6098-6106. [PMID: 33683243 DOI: 10.1039/d0cp06350a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photodissociation of di- and tri-halogenated methanes including CH2BrCl and CHBr2Cl at 248 nm was investigated using cavity ringdown absorption spectroscopy (CRDS). The spectra of the BrCl(v'' = 2, 3) and Br2(v'' = 1, 2) fragments were probed over the wavelength range of 594.5-596 nm in the B3Π+0u ← X1Σ+g and B3Π (0+) ← X1Σ+ transitions, respectively. Their corresponding spectra were simulated for assignment of rotational lines at a given vibrational level. The quantum yields for Br2 eliminated from CHBr2Cl and BrCl from CH2BrCl were determined to be 0.048 ± 0.018 and 0.037 ± 0.014, respectively. The photodissociation of CHBr2Cl yielded only the Br2 fragment, but not the BrCl fragment in the experiments. An ab initio theoretical method based on the CCSD(T)//B3LYP/6-311g(d,p) level was employed to evaluate the potential energy surface for the dissociation pathways to produce Br2 and BrCl from CHBr2Cl, which encountered a transition state barrier of 445 and 484 kJ mol-1, respectively. The corresponding RRKM rate constants were calculated to show that the branching ratio of (Br2/BrCl) is ∼20. The BrCl spectrum is expected to be obscured by the much larger Br2 spectrum, explaining why BrCl fragments cannot be detected in the photolysis of CHBr2Cl.
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Affiliation(s)
- Balaganesh Muthiah
- Department of Chemistry, National Taiwan Univeristy, Taipei 106, Taiwan.
| | - Toshio Kasai
- Department of Chemistry, National Taiwan Univeristy, Taipei 106, Taiwan. and Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
| | - King-Chuen Lin
- Department of Chemistry, National Taiwan Univeristy, Taipei 106, Taiwan. and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
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3
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Lin KC, Muthiah B, Chang HP, Kasai T, Chang YP. Halogen-related photodissociation in atmosphere: characterisation of atomic halogen, molecular halogen, and hydrogen halide. INT REV PHYS CHEM 2020. [DOI: 10.1080/0144235x.2020.1822590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- King-Chuen Lin
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
| | | | - Hsiu-Pu Chang
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Toshio Kasai
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
- Institute of Scientific and Industrial Research, Osaka University, Osaka, Japan
| | - Yuan-Pin Chang
- Department of Chemistry, National Sun Yat-sen University, Kaohsiung, Taiwan
- Aerosol Science Research Center, National Sun Yat-sen University, Kaohsiung, Taiwan
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung, Taiwan
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4
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Chen JY, Selvaraju M, Lin YT, Dhole S, Lin CY, Sun CM. Molecular Iodine-Promoted [3 + 2] Oxidative Cyclization for the Synthesis of Heteroarene-Fused [1,2,4] Thiadiazoles/Selenadiazoles. J Org Chem 2020; 85:5570-5579. [PMID: 32249566 DOI: 10.1021/acs.joc.0c00421] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Two new classes of heteroarene-fused [1,2,4]thiadiazole and [1,2,4]selenadiazole are synthesized through the iodine-mediated [3 + 2] oxidative cyclization of 2-aminoheteroarenes and isothiocyanates/isoselenocyanates. This oxidative [3 + 2] annulation strategy is highly regiospecific to proceed a selective C-N bond formation at the endo-nitrogen of 2-aminoheteroarenes followed by an intramolecular oxidative N-S/N-Se bond formation. It is the first example of an I2-mediated oxidative nitrogen-selenium (N-Se) bond formation.
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Affiliation(s)
- Jin-Yu Chen
- Department of Applied Chemistry, National Chiao Tung University, 1001 Ta-Hsueh Road, Hsinchu 300-10, Taiwan
| | - Manikandan Selvaraju
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Yen-Tzu Lin
- Department of Applied Chemistry, National Chiao Tung University, 1001 Ta-Hsueh Road, Hsinchu 300-10, Taiwan
| | - Sandip Dhole
- Department of Applied Chemistry, National Chiao Tung University, 1001 Ta-Hsueh Road, Hsinchu 300-10, Taiwan
| | - Chih-Yu Lin
- Department of Applied Chemistry, National Chiao Tung University, 1001 Ta-Hsueh Road, Hsinchu 300-10, Taiwan
| | - Chung-Ming Sun
- Department of Applied Chemistry, National Chiao Tung University, 1001 Ta-Hsueh Road, Hsinchu 300-10, Taiwan.,Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, 100, Shih-Chuan 1st Road, Kaohsiung 807-08, Taiwan
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5
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Wei Z, Li J, Zhang H, Lu Y, Yang M, Loh ZH. Ultrafast dissociative ionization and large-amplitude vibrational wave packet dynamics of strong-field-ionized di-iodomethane. J Chem Phys 2019; 151:214308. [PMID: 31822095 DOI: 10.1063/1.5132967] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We employ few-cycle pulses to strong-field-ionize di-iodomethane (CH2I2) and femtosecond extreme ultraviolet (XUV) transient absorption spectroscopy to investigate the subsequent ultrafast dissociative ionization and vibrational wave packet dynamics. Probing in the spectral region of the I 4d core-level transitions, the time-resolved XUV differential absorption spectra reveal the population of several electronic states of CH2I2 + by strong-field ionization. Global analysis reveals three distinct time scales for the observed dynamics: 20 ± 2 fs, 49 ± 6 fs, and 157 ± 9 fs, ascribed to relaxation of the CH2I2 + parent ion from the Franck-Condon region, dissociation of high-lying excited states of CH2I2 + to I+ (3P2), CH2I, and I2 + (2Π3/2,g), and dissociation of CH2I2 + to I (2P3/2) and CH2I+, respectively. Oscillatory features in the time-resolved XUV differential absorption spectra point to the generation of vibrational wave packets in both the residual CH2I2 and the CH2I2 + parent ion. Analysis of the oscillation frequencies and phases reveals, in the case of neutral CH2I2, C-I symmetric stretching induced by bond softening and I-C-I bending driven by a combination of bond softening and R-selective depletion. In the case of CH2I2 +, both the fundamental and first overtone frequencies of the I-C-I bending mode are observed, indicating large-amplitude I-C-I bending motion, in good agreement with results obtained from ab initio simulations of the XUV transition energy along the I-C-I bend coordinate. These results show that femtosecond XUV absorption spectroscopy is well-suited for studying ultrafast photodissociation and vibrational wave packet dynamics.
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Affiliation(s)
- Zhengrong Wei
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Jialin Li
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Huimin Zhang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Yunpeng Lu
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Minghui Yang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Zhi-Heng Loh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
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6
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Muthiah B, Paredes-Roibás D, Kasai T, Lin KC. Photodissociation of CH 2BrI using cavity ring-down spectroscopy: in search of a BrI elimination channel. Phys Chem Chem Phys 2019; 21:13943-13949. [PMID: 30137071 DOI: 10.1039/c8cp04130j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photodissociation of CH2BrI was investigated in search of unimolecular elimination of BrI via a primary channel using cavity ring-down absorption spectroscopy (CRDS) at 248 nm. The BrI spectra were acquired involving the first three ground vibrational levels corresponding to A3Π1 ← X1Σ+ transition. With the aid of spectral simulation, the BrI rotational lines were assigned. The nascent vibrational populations for v'' = 0, 1, and 2 levels are obtained with a population ratio of 1 : (0.58 ± 0.10) : (0.34 ± 0.05), corresponding to a Boltzmann-like vibrational temperature of 713 ± 49 K. The quantum yield of the ground state BrI elimination reaction is determined to be 0.044 ± 0.014. The CCSD(T)//B3LYP/MIDI! method was employed to explore the potential energy surface for the unimolecular elimination of BrI from CH2BrI.
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Affiliation(s)
- Balaganesh Muthiah
- Department of Chemistry, National Taiwan Univeristy, Taipei 106, Taiwan.
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7
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Wu H, Xue Y, Wen J, Wang H, Bai L, He W, Sun R, Zheng W. BrCl+ elimination from Coulomb explosion of 1,2-bromochloroethane induced by intense femtosecond laser fields. RSC Adv 2019; 9:31853-31859. [PMID: 35530799 PMCID: PMC9072746 DOI: 10.1039/c9ra07498h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 10/03/2019] [Indexed: 12/14/2022] Open
Abstract
By using a dc-slice imaging technique, photodissociation of 1,2-C2H4BrCl was investigated at 800 nm looking for heteronuclear unimolecular ion elimination of BrCl+ in an 80 fs laser field. The occurrence of fragment ion BrCl+ in the mass spectrum verified the existence of a unimolecular decomposition channel of BrCl+ in this experiment. The relative quantum yield of the BrCl+ channel was measured to be 0.8%. By processing and analyzing the velocity and angular distributions obtained from the corresponding sliced images of BrCl+ and its partner ion C2H4+, we concluded that BrCl+ came from Coulomb explosion of the 1,2-bromochloroethane dication 1,2-C2H4BrCl2+. With the aid of quantum chemical calculations at the M06-2X/def2-TZVP level, the potential energy surface for BrCl+ detachment from 1,2-C2H4BrCl2+ has been examined in detail. According to the ab initio calculations, two transition state structures tended to correlate with the reactant 1,2-C2H4BrCl2+ and the products BrCl+ + C2H4+. In this entire dissociation process, the C–Br and C–Cl bond lengths were observed to elongate asymmetrically, that is, the C–Br chemical bond broke firstly, and subsequently a new Br–Cl chemical bond started to emerge while the C–Cl bond continued to exist for a while. Hence, an asynchronous concerted elimination mechanism was favored for BrCl+ detachment. Concerted elimination of the molecular ion BrCl+ from Coulomb explosion of 1,2-bromochloroethane was studied theoretically and experimentally.![]()
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Affiliation(s)
- Hua Wu
- School of Sciences
- Xi'an Shiyou University
- Shanxi 710065
- P. R. China
| | - Yuanxin Xue
- School of Sciences
- Xi'an Shiyou University
- Shanxi 710065
- P. R. China
| | - Junqing Wen
- School of Sciences
- Xi'an Shiyou University
- Shanxi 710065
- P. R. China
| | - Hui Wang
- School of Sciences
- Xi'an Shiyou University
- Shanxi 710065
- P. R. China
| | - Lihua Bai
- School of Sciences
- Xi'an Shiyou University
- Shanxi 710065
- P. R. China
| | - Wanlin He
- School of Sciences
- Xi'an Shiyou University
- Shanxi 710065
- P. R. China
| | - Ruijuan Sun
- School of Sciences
- Xi'an Shiyou University
- Shanxi 710065
- P. R. China
| | - Wenli Zheng
- School of Sciences
- Xi'an Shiyou University
- Shanxi 710065
- P. R. China
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8
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Paredes-Roibás D, Balaganesh M, Kasai T, Gavira-Vallejo JM, Lin KC. Cavity Ring-Down Absorption Spectroscopy: Optical Characterization of ICl Product in Photodissociation of CH 2ICl at 248 nm. J Phys Chem A 2018; 122:8344-8353. [PMID: 30278130 DOI: 10.1021/acs.jpca.8b07012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Iodine monochloride (ICl) elimination from one-photon dissociation of CH2ICl at 248 nm is monitored by cavity ring-down absorption spectroscopy (CRDS). The spectrum of ICl is acquired in the transition of B3Π0 ← X1Σ+ and is confirmed to result from a primary photodissociation, that is, CH2ICl + hν → CH2 + ICl. The vibrational population ratio is determined with the aid of spectral simulation to be 1:(0.36 ± 0.10):(0.11 ± 0.05) for the vibrational levels ν = 0, 1, and 2 in the ground electronic state, corresponding to a Boltzmann-like vibrational temperature of 535 ± 69 K. The quantum yield of the ICl molecular channel for the reaction is obtained to be 0.052 ± 0.026 using a relative method in which the scheme CH2Br2 → CH2 + Br2 is adopted as the reference reaction. The ICl product contributed by the secondary collisions is minimized such that its quantum yield obtained is not overestimated. With the aid of the CCSD(T)//B3LYP/MIDI! level of theory, the ICl elimination from CH2ICl is evaluated to follow three pathways via either (1) a three-center transition state or (2) two isomerization transition states. However, the three-center concerted mechanism is verified to be unfavorable.
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Affiliation(s)
- Denís Paredes-Roibás
- Departamento de Ciencias y Técnicas Fisicoquímicas , Facultad de Ciencias, Universidad Nacional de Educación a Distancia (UNED) , Paseo de la Senda del Rey 9 , E-28040 Madrid , Spain
| | - Muthiah Balaganesh
- Department of Chemistry , National Taiwan Univeristy , Taipei 10617 , Taiwan.,Institute of Atomic and Molecular Sciences , Academia Sinica , Taipei 10617 , Taiwan
| | - Toshio Kasai
- Department of Chemistry , National Taiwan Univeristy , Taipei 10617 , Taiwan.,Institute of Scientific and Industrial Research , Osaka University , Ibaraki, Osaka 567-0047 , Japan
| | - José María Gavira-Vallejo
- Departamento de Ciencias y Técnicas Fisicoquímicas , Facultad de Ciencias, Universidad Nacional de Educación a Distancia (UNED) , Paseo de la Senda del Rey 9 , E-28040 Madrid , Spain
| | - King Chuen Lin
- Department of Chemistry , National Taiwan Univeristy , Taipei 10617 , Taiwan.,Institute of Atomic and Molecular Sciences , Academia Sinica , Taipei 10617 , Taiwan
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9
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Borin VA, Matveev SM, Budkina DS, El-Khoury PZ, Tarnovsky AN. Direct photoisomerization of CH 2I 2vs. CHBr 3 in the gas phase: a joint 50 fs experimental and multireference resonance-theoretical study. Phys Chem Chem Phys 2018; 18:28883-28892. [PMID: 27722308 DOI: 10.1039/c6cp05129d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Femtosecond transient absorption measurements powered by 40 fs laser pulses reveal that ultrafast isomerization takes place upon S1 excitation of both CH2I2 and CHBr3 in the gas phase. The photochemical conversion process is direct and intramolecular, i.e., it proceeds without caging media that have long been implicated in the photo-induced isomerization of polyhalogenated alkanes in condensed phases. Using multistate complete active space second order perturbation theory (MS-CASPT2) calculations, we investigate the structure of the photochemical reaction paths connecting the photoexcited species to their corresponding isomeric forms. Unconstrained minimum energy paths computed starting from the S1 Franck-Condon points lead to S1/S0 conical intersections, which directly connect the parent CHBr3 and CH2I2 molecules to their isomeric forms. Changes in the chemical bonding picture along the S1/S0 isomerization reaction path are described using multireference average coupled pair functional (MRACPF) calculations in conjunction with natural resonance theory (NRT) analysis. These calculations reveal a complex interplay between covalent, radical, ylidic, and ion-pair dominant resonance structures throughout the nonadiabatic photochemical isomerization processes described in this work.
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Affiliation(s)
- Veniamin A Borin
- Center for Photochemical Sciences, Department of Chemistry, Bowling Green State University, Bowling Green, Ohio, USA.
| | - Sergey M Matveev
- Center for Photochemical Sciences, Department of Chemistry, Bowling Green State University, Bowling Green, Ohio, USA.
| | - Darya S Budkina
- Center for Photochemical Sciences, Department of Chemistry, Bowling Green State University, Bowling Green, Ohio, USA.
| | - Patrick Z El-Khoury
- Physical Sciences Division, Pacific Northwest National Laboratory, P. O. Box 999, Richland, WA 99352, USA
| | - Alexander N Tarnovsky
- Center for Photochemical Sciences, Department of Chemistry, Bowling Green State University, Bowling Green, Ohio, USA.
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10
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Huang TK, Chen BJ, Lin KC, Lin L, Sun BJ, Chang AHH. Cl2 Elimination in 248 nm Photolysis of (COCl)2 Probed with Cavity Ring-Down Absorption Spectroscopy. J Phys Chem A 2017; 121:2888-2895. [DOI: 10.1021/acs.jpca.6b12810] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ting-Kang Huang
- Department of Chemistry, National Taiwan University,
and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
| | - Bo-Jung Chen
- Department of Chemistry, National Taiwan University,
and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
| | - King-Chuen Lin
- Department of Chemistry, National Taiwan University,
and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
| | - Lin Lin
- Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan
| | - Bing-Jian Sun
- Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan
| | - A. H. H. Chang
- Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan
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11
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Huang M, Kline N, Miller TA, Dawes R. Studies via Near-Infrared Cavity Ringdown Spectroscopy and Electronic Structure Calculations of the Products of the Photolysis of Dihalomethane/N2/O2 Mixtures. J Phys Chem A 2017; 121:98-112. [DOI: 10.1021/acs.jpca.6b10632] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Meng Huang
- Department
of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Neal Kline
- Department
of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
- Research
and Technology Directorate, Edgewood Chemical Biological Center, Aberdeen
Proving Ground, Gunpowder, Maryland 21010-5424, United States
| | - Terry A. Miller
- Department
of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Richard Dawes
- Department
of Chemistry, Missouri University of Science and Technology, Rolla, Missouri 65409, United States
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12
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Toulson BW, Alaniz JP, Grant Hill J, Murray C. Near-UV photodissociation dynamics of CH2I2. Phys Chem Chem Phys 2016; 18:11091-103. [DOI: 10.1039/c6cp01063f] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The near-UV photodissociation dynamics of CH2I2has been investigated using a combination of velocity-map (slice) ion imaging andab initiocalculations characterizing the excited states.
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Affiliation(s)
| | | | - J. Grant Hill
- Department of Chemistry
- University of Sheffield
- Sheffield S3 7HF
- UK
| | - Craig Murray
- Department of Chemistry
- University of California, Irvine
- Irvine
- USA
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13
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Lin KC, Tsai PY. Molecular halogen elimination from halogen-containing compounds in the atmosphere. Phys Chem Chem Phys 2014; 16:7184-98. [PMID: 24622955 DOI: 10.1039/c3cp54828g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Atmospheric halogen chemistry has drawn much attention, because the halogen atom (X) playing a catalytic role may cause severe stratospheric ozone depletion. Atomic X elimination from X-containing hydrocarbons is recognized as the major primary dissociation process upon UV-light irradiation, whereas direct elimination of the X2 product has been seldom discussed or remained a controversial issue. This account is intended to review the detection of X2 primary products using cavity ring-down absorption spectroscopy in the photolysis at 248 nm of a variety of X-containing compounds, focusing on bromomethanes (CH2Br2, CF2Br2, CHBr2Cl, and CHBr3), dibromoethanes (1,1-C2H4Br2 and 1,2-C2H4Br2) and dibromoethylenes (1,1-C2H2Br2 and 1,2-C2H2Br2), diiodomethane (CH2I2), thionyl chloride (SOCl2), and sulfuryl chloride (SO2Cl2), along with a brief discussion on acyl bromides (BrCOCOBr and CH2BrCOBr). The optical spectra, quantum yields, and vibrational population distributions of the X2 fragments have been characterized, especially for Br2 and I2. With the aid of ab initio calculations of potential energies and rate constants, the detailed photodissociation mechanisms may be comprehended. Such studies are fundamentally important to gain insight into the dissociation dynamics and may also practically help to assess the halogen-related environmental variation.
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Affiliation(s)
- King-Chuen Lin
- Department of Chemistry, National Taiwan University, Taipei, and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan.
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14
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Tu CP, Cheng HI, Chang BC. Spectroscopic study of the I2 formation from the photolysis of iodomethanes (CHI3, CH2I2, CH3I, and CH2ICl) at different wavelengths. J Phys Chem A 2013; 117:13572-7. [PMID: 23952939 DOI: 10.1021/jp407599x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Emission spectra following the photolysis of iodomethanes (CHI3, CH2I2, CH3I, and CH2ICl) at 266 nm were recorded in a slow flow cell. In addition to emission from the electronically excited species including CH (A(2)Δ, B(2)Σ(-), and C(2)Σ(+)), C2 (d(3)Πg), and atomic iodine ((4)P(o)), a series of emission bands was observed in the 12,000-19,000 cm(-1) region. The dominant structure of these emission bands was verified as the I2 B(3)Π(+)(0,u)-X(1)Σ(+)g emission at the 532 nm excitation, and the observed I2 was formed from collisions between iodine atoms generated from the C-I bond dissociation in these iodomethanes. The I2 emission spectra following the photolysis of CH2I2 at different wavelengths were acquired, and the threshold energy for the first C-I bond cleavage was determined to be 208 ± 1 kJ mol(-1). We also obtained the emission spectra of pure I2 at several visible excitation wavelengths for comparison with those from the photolysis of iodomethanes, and a least-squares global fit of the observed I2 emission bands yields more accurate anharmonicity parameters for the vibrational structure in the I2 B-X transition.
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Affiliation(s)
- Cian-Ping Tu
- Department of Chemistry, National Central University , 300 Jungda Road, Jhongli 32001, Taiwan
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15
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Ouyang B, McLeod MW, Jones RL, Bloss WJ. NO3 radical production from the reaction between the Criegee intermediate CH2OO and NO2. Phys Chem Chem Phys 2013; 15:17070-5. [DOI: 10.1039/c3cp53024h] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Saha A, Kawade M, Upadhyaya HP, Kumar A, Naik PD, Bajaj P. Resonance enhanced multiphoton ionization time-of-flight (REMPI-TOF) study of phosphorous oxychloride (POCl3) dissociation at 235nm: Dynamics of Cl(2Pj) formation. Chem Phys 2012. [DOI: 10.1016/j.chemphys.2012.09.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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