Characterization of molecular channel in photodissociation of SOCl<sub>2</sub> at 248 nm: Cl<sub>2</sub> probing by cavity ring-down absorption spectroscopy

Chen, Bo-Jung; Tsai, Po‐Yu; Huang, Ting-Kang; Xia, Zhu-Hong; Lin, King‐Chuen; Chiou, Chuei-Jhih; Sun, Bing‐Jian; Chang, Agnes H. H.

doi:10.1039/c4cp06043a

Cited by 9 publications

(18 citation statements)

References 51 publications

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“…In order to verify whether the obtained transition states correspond to the desired process, internal reaction coordinate (IRC) calculations were carried out. On the basis of the obtained stationary points, more accurate energies were then obtained by single‐point calculations at the CCSD(T) level employing the correlation consistent triple ζ basis set cc‐pVTZ, which has been proved to achieve good agreement between computational and experimental results . Because of the lack of proper scaling factors for the level of theory used here, the CCSD(T) energies were corrected for the unscaled ω B97X‐D ZPVE.…”

Section: Theoretical Methodsmentioning

confidence: 99%

Vacuum ultraviolet photoionization mass spectrometric study of cyclohexene

et al. 2016

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In this work, photoionization and dissociation of cyclohexene have been studied by means of coupling a reflectron time-of-flight mass spectrometer with the tunable vacuum ultraviolet (VUV) synchrotron radiation. The adiabatic ionization energy of cyclohexene as well as the appearance energies of its fragment ions C6 H9 (+) , C6 H7 (+) , C5 H7 (+) , C5 H5 (+) , C4 H6 (+) , C4 H5 (+) , C3 H5 (+) and C3 H3 (+) were derived from the onset of the photoionization efficiency (PIE) curves. The optimized structures for the transition states and intermediates on the ground state potential energy surfaces related to photodissociation of cyclohexene were characterized at the ωB97X-D/6-31+g(d,p) level. The coupled cluster method, CCSD(T)/cc-pVTZ, was employed to calculate the corresponding energies with the zero-point energy corrections by the ωB97X-D/6-31+g(d,p) approach. Combining experimental and theoretical results, possible formation pathways of the fragment ions were proposed and discussed in detail. The retro-Cope rearrangement was found to play a crucial role in the formation of C4 H6 (+) , C4 H5 (+) and C3 H5 (+) . Intramolecular hydrogen migrations were observed as dominant processes in most of the fragmentation pathways of cyclohexene. The present research provides a clear picture of the photoionization and dissociation processes of cyclohexene in the 8- to 15.5-eV photon energy region.

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Section: Theoretical Methodsmentioning

confidence: 99%

Vacuum ultraviolet photoionization mass spectrometric study of cyclohexene

et al. 2016

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“…In comparison with this result, the quantum yields of Br 2 and I 2 produced from photodissociation of CH 2 Br 2 23,27 and CH 2 I 2 , 26 at the same wavelength yielded values of 0.21 ± 0.06 and 0.004 ± 0.0025, respectively. The quantum yield for the ICl channel from CH 2 ICl is smaller by a factor of 4 than that of Br 2 from CH 2 Br 2 but 10 times larger than that of I 2 from CH 2 I 2 .…”

Section: Resultsmentioning

confidence: 56%

“…Alternatively, the quantum yield for the ICl channel can be determined by the indirect method, when the quantum yields of similar reactions are well established. The Br 2 formation from CH 2 Br 2 photodissociation studied in previous work was chosen as a reference reaction with a quantum yield of 0.21 ± 0.06. , The following equation is used to calculate the quantum yield of ICl production where [ICl] and [Br 2 ] are concentrations obtained from the experiment, n CH 2 ICl and n CH 2 Br 2 are the number densities of CH 2 ICl and CH 2 Br 2 , and σ CH 2 ICl and σ CH 2 Br 2 are the absorption cross sections of CH 2 ICl and CH 2 Br 2 at 248 nm. We evaluated the Br 2 concentration to be 8.1 × 10 15 molecules/cm 3 at the rotational line of 519.68 nm by ring-down time measurements, and n CH 2 Br 2 was experimentally controlled to 596 mTorr.…”

Section: Resultsmentioning

confidence: 99%

“…The experimental setup of the CRDS apparatus has been described elsewhere − In brief, the CRDS is composed of three units, a ring-down flow cell, the photolysis-and-probe laser system, and the ring-down time detection and signal analysis. A KrF excimer laser, emitting at 248 nm with an energy of 10–30 mJ/pulse, was employed for photolysis.…”

Section: Methodsmentioning

confidence: 99%

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Cavity Ring-Down Absorption Spectroscopy: Optical Characterization of ICl Product in Photodissociation of CH₂ICl at 248 nm

et al. 2018

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Iodine monochloride (ICl) elimination from one-photon dissociation of CH 2 ICl at 248 nm is monitored by cavity ring-down absorption spectroscopy (CRDS). The spectrum of ICl is acquired in the transition of B 3 Π 0 ← X 1 Σ + and is confirmed to result from a primary photodissociation, that is, CH 2 ICl + hν → CH 2 + 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 CH 2 Br 2 → CH 2 + Br 2 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 CH 2 ICl 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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“…As demonstrated with cavity ring-down absorption spectroscopy (CRDS), − we have successfully monitored the Br 2 and I 2 fragments eliminated from a series of halogen-containing hydrocarbons. We also observed a primary product of Br 2 in one-photon dissociation of (COBr) 2 at 248 nm and proposed a plausible reaction mechanism for the products Br 2 + 2CO .…”

Section: Introductionmentioning

confidence: 99%

Cl₂ Elimination in 248 nm Photolysis of (COCl)₂ Probed with Cavity Ring-Down Absorption Spectroscopy

et al. 2017

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Cavity ring-down absorption spectroscopy (CRDS) is employed to investigate one-photon dissociation of (COCl) at 248 nm obtaining a primary Cl elimination channel. A ratio of vibrational population is estimated to be 1:(0.12 ± 0.03):(0.011 ± 0.003) for the v = 0, 1, and 2 levels. The quantum yield of Cl molecular channel is obtained to be 0.8 ± 0.4 initiated from the X̃ A ground state surface (COCl) via internal conversion. The obtained total quantum yield is attributed to both primary ((COCl) + hν → 2CO + Cl) and secondary reactions (dominated by Cl + COCl → Cl + CO). The former is estimated to share a yield of >0.14, while the latter contributes up to 0.66. The photodissociation pathway to the molecular products is calculated to proceed via a four-center transition state (TS) from which Cl is eliminated synchronously. Installation of the mirrors with reflectivity of 99.995% in the CRDS apparatus prolongs the ring-down time to 70 μs, thus allowing for the contribution from 17% up to 66% of the total Cl yield from secondary reaction depending on the reaction temperature. Despite uncertainty in determining the product yield, the primary Cl dissociation channel eliminated from (COCl) is observed for the first time.

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Characterization of molecular channel in photodissociation of SOCl₂ at 248 nm: Cl₂ probing by cavity ring-down absorption spectroscopy

Cited by 9 publications

References 51 publications

Vacuum ultraviolet photoionization mass spectrometric study of cyclohexene

Vacuum ultraviolet photoionization mass spectrometric study of cyclohexene

Cavity Ring-Down Absorption Spectroscopy: Optical Characterization of ICl Product in Photodissociation of CH₂ICl at 248 nm

Cl₂ Elimination in 248 nm Photolysis of (COCl)₂ Probed with Cavity Ring-Down Absorption Spectroscopy

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Characterization of molecular channel in photodissociation of SOCl2 at 248 nm: Cl2 probing by cavity ring-down absorption spectroscopy

Cited by 9 publications

References 51 publications

Vacuum ultraviolet photoionization mass spectrometric study of cyclohexene

Vacuum ultraviolet photoionization mass spectrometric study of cyclohexene

Cavity Ring-Down Absorption Spectroscopy: Optical Characterization of ICl Product in Photodissociation of CH2ICl at 248 nm

Cl2 Elimination in 248 nm Photolysis of (COCl)2 Probed with Cavity Ring-Down Absorption Spectroscopy

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Characterization of molecular channel in photodissociation of SOCl₂ at 248 nm: Cl₂ probing by cavity ring-down absorption spectroscopy

Cavity Ring-Down Absorption Spectroscopy: Optical Characterization of ICl Product in Photodissociation of CH₂ICl at 248 nm

Cl₂ Elimination in 248 nm Photolysis of (COCl)₂ Probed with Cavity Ring-Down Absorption Spectroscopy