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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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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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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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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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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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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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Sun G, Sommar J, Feng X, Lin CJ, Ge M, Wang W, Yin R, Fu X, Shang L. Mass-Dependent and -Independent Fractionation of Mercury Isotope during Gas-Phase Oxidation of Elemental Mercury Vapor by Atomic Cl and Br. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:9232-41. [PMID: 27501307 DOI: 10.1021/acs.est.6b01668] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
This study presents the first measurement of Hg stable isotope fractionation during gas-phase oxidation of Hg(0) vapor by halogen atoms (Cl(•), Br(•)) in the laboratory at 750 ± 1 Torr and 298 ± 3 K. Using a relative rate technique, the rate coefficients for Hg(0)+Cl(•) and Hg(0)+Br(•) reactions are determined to be (1.8 ± 0.5) × 10(-11) and (1.6 ± 0.8) × 10(-12) cm(3) molecule(-1) s(-1), respectively. Results show that heavier isotopes are preferentially enriched in the remaining Hg(0) during Cl(•) initiated oxidation, whereas being enriched in the product during oxidation by Br(•). The fractionation factors for (202)Hg/(198)Hg during the Cl(•) and Br(•) initiated oxidations are α(202/198) = 0.99941 ± 0.00006 (2σ) and 1.00074 ± 0.00014 (2σ), respectively. A Δ(199)Hg/Δ(201)Hg ratio of 1.64 ± 0.30 (2σ) during oxidation of Hg(0) by Br atoms suggests that Hg-MIF is introduced by the nuclear volume effect (NVE). In contrast, the Hg(0) + Cl(•) reaction produces a Δ(199)Hg/Δ(201)Hg-slope of 1.89 ± 0.18 (2σ), which in addition to a high degree of odd-mass-number isotope MIF suggests impacts from MIF effects other than NVE. This reaction also exhibits significant MIF of (200)Hg (Δ(200)Hg, up to -0.17‰ in the reactant) and is the first physicochemical process identified to trigger (200)Hg anomalies that are frequently detected in atmospheric samples.
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Affiliation(s)
- Guangyi Sun
- University of Chinese Academy of Sciences, Beijing 100190, China
| | | | | | - Che-Jen Lin
- Center for Advances in Water and Air Quality, Lamar University , Beaumont, Texas 77710, United States
| | - Maofa Ge
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, China
| | - Weigang Wang
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, China
| | - Runsheng Yin
- Environmental Chemistry and Technology Program, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
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Chen BJ, Tsai PY, Huang TK, Xia ZH, Lin KC, Chiou CJ, Sun BJ, Chang AHH. Characterization of molecular channel in photodissociation of SOCl2 at 248 nm: Cl2 probing by cavity ring-down absorption spectroscopy. Phys Chem Chem Phys 2015; 17:7838-47. [PMID: 25715942 DOI: 10.1039/c4cp06043a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A primary elimination channel of the chlorine molecule in the one-photon dissociation of SOCl2 at 248 nm was investigated using cavity ring-down absorption spectroscopy (CRDS). By means of spectral simulation, the ratio of the vibrational population in the v = 0, 1, and 2 levels was evaluated to be 1 : (0.10 ± 0.02) : (0.009 ± 0.005), corresponding to a Boltzmann vibrational temperature of 340 ± 30 K. The Cl2 molecular channel was obtained with a quantum yield of 0.4 ± 0.2 from the X(1)A' ground state of SOCl2via internal conversion. The dissociation mechanism differs from a prior study where a smaller yield of <3% was obtained, initiated from the 2(1)A' excited state. Temperature-dependence measurements of the Cl2 fragment turn out to support our mechanism. With the aid of ab initio potential energy calculations, two dissociation routes to the molecular products were found, including one synchronous dissociation pathway via a three-center transition state (TS) and the other sequential dissociation pathway via a roaming-mediated isomerization TS. The latter mechanism with a lower energy barrier dominates the dissociation reaction.
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Affiliation(s)
- Bo-Jung Chen
- Department of Chemistry, National Taiwan University, Taipei, Taiwan.
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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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Fan H, Tsai PY, Lin KC, Lin CW, Yan CY, Yang SW, Chang AHH. Molecular elimination of Br2 in photodissociation of CH2BrC(O)Br at 248 nm using cavity ring-down absorption spectroscopy. J Chem Phys 2012; 137:214304. [DOI: 10.1063/1.4767346] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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