Dissociation rate of hot benzene

Tsai, Shang‐Ting; Lin, Ching‐Fuh; Lee, Yuan T.; Ni, Chi-Kung

doi:10.1063/1.481774

Cited by 78 publications

(44 citation statements)

References 29 publications

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“…Yokoyama et al [31] have investigated the photodissociation of benzene using 193 nm photon (hv = 6.4 eV). A similar research has been reported by Tsai et al [32]. In our experiments, 157 nm photon (hv = 7.9 eV) has been used for ionization of species.…”

Section: Dissociative Ionization By F 2 -Lasersupporting

confidence: 52%

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Determinations of Intermediate Neutral Species in Hydrocarbon Discharge Plasma

Liu

Wang

Xiao

et al. 2010

Plasma Chem Plasma Process

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This work reports laser ionization combined with Time-Of-Flight (TOF) mass spectrometry investigation on intermediate species in the hydrocarbon plasma of atmospheric-pressure fast-flow pulsed dc-discharge. All neutral intermediate species including transient radicals from benzene/Ar discharge have been characterized by a molecular beam sampling combined with TOF mass spectrometry. This shows that with a hydrocarbon gas mixture of 0.3% C 6 H 6 in Ar discharge the intermediate species consist of simple radicals (such as C 2 , C 5 H 5 , C 7 H 7 ) and polycyclic organic molecules (C 10 H 8 , C 13 H 10 , C 14 H 10 ). Theoretical studies on total energies and ionization potentials of the intermediate species have been carried out using the hybrid density functional theory. Effect of the ionization potential on mass spectral intensity has been discussed. Based on the observed data, the possible major neutral reaction channels of the plasma chemistry have been discussed. The developed experimental method has implications in volatile organic compounds removing and impurities diagnosis in Tokamak edge-plasma.

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Section: Dissociative Ionization By F 2 -Lasersupporting

confidence: 52%

“…e) and the formation of small neutrals (Eqs. [30][31][32][33][34][35]. But the highly excited state C 6 H 6 * is efficiently quenched by collisions with the background gas argon and thereby should contribute weakly to its dissociation.…”

Section: Penning Ionization In Discharge Plasmamentioning

confidence: 99%

Determinations of Intermediate Neutral Species in Hydrocarbon Discharge Plasma

Liu

Wang

Xiao

et al. 2010

Plasma Chem Plasma Process

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“…Deactivation of the excited electronic states formed by absorption of ultraviolet photons lead to a transient highly excited state of the ground electronic state (C 6 H 6 *). This state has a lifetime of up to 2 ms and subsequently fragments into the photodissociation products [ Tsai et al , 2000]. C 6 H 6 * can also be deactivated by collisions with N 2 [ Nakashima and Yoshihara , 1982].…”

Section: Chemical Modelsmentioning

confidence: 99%

Formation and distribution of benzene on Titan

2008

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[1] We present a study of the formation and distribution of benzene (C 6 H 6 ) on Titan. Analysis of the Cassini Mass Spectrometer (INMS) measurements of benzene densities on 12 Titan passes shows that the benzene signal exhibits an unusual time dependence, peaking $20 s after closest approach, rather than at closest approach. We show that this behavior can be explained by recombination of phenyl radicals (C 6 H 5 ) with H atoms on the walls of the instrument and that the measured signal is a combination of (1) C 6 H 6 from the atmosphere and (2) C 6 H 6 formed within the instrument. In parallel, we investigate Titan benzene chemistry with a set of photochemical models. A model for the ionosphere predicts that the globally averaged production rate of benzene by ion-molecule reactions is $10 7 cm À2 s À1 , of the same order of magnitude as the production rate by neutral reactions of $4 Â 10 6 cm À2 s À1 . We show that benzene is quickly photolyzed in the thermosphere, and that C 6 H 5 radicals, the main photodissociation products, are $3 times as abundant as benzene. This result is consistent with the phenyl/benzene ratio required to match the INMS observations. Loss of benzene occurs primarily through reaction of phenyl with other radicals, leading to the formation of complex aromatic species. These species, along with benzene, diffuse downward, eventually condensing near the tropopause. We find a total production rate of solid aromatics of $10 À15 g cm À2 s À1 , corresponding to an accumulated surface layer of $3 m.

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“…Benzene is excited near 3.3 m not only by near-IR solar radiation but also by solar UV and visible radiation. We have computed the excitation of benzene produced by UV and visible solar radiation taking into account the cross-sections of benzene in the UV and visible [Etzkorn et al, 1999;Feng et al, 2002], the solar UV-VIS flux at Titan's top atmosphere [Rottman, 2005], and a mean efficiency of 10% to 60% for wavelengths from 160 to 245 nm [Tsai et al, 2000]. We have found, however, an excitation similar to that produced by the near-IR pumping.…”

Section: Analysis Of the "Unidentified" Emissionmentioning

confidence: 99%

“…"Hot" benzene [Tsai et al, 2000] could be another candidate for explaining the UnE. Benzene is excited near 3.3 m not only by near-IR solar radiation but also by solar UV and visible radiation.…”

Section: Analysis Of the "Unidentified" Emissionmentioning

confidence: 99%

An unidentified emission in Titan's upper atmosphere

Dinelli

López‐Puertas

Adriani

et al. 2013

Geophysical Research Letters

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[1] We have analyzed limb daytime observations of Titan's upper atmosphere at 3.3 m, acquired by the visual-infrared mapping spectrometer (VIMS) on Cassini. They were previously studied by García-Comas et al. (2011) to derive CH 4 densities. Here, we report an unidentified emission peaking around 3.28 m, hidden under the methane R branch. This emission is very strong, with intensity comparable to the CH 4 bands located in the same spectral region. It presents a maximum at about 950 km and extends from 600 km up to 1250 km. It is definitely pumped by solar radiation since it vanishes at night. Our analysis shows that neither methane nor the major hydrocarbon compounds already discovered in Titan's upper atmosphere are responsible for it. We have discarded many other potential candidates and suggest that the unidentified emission might be caused by aromatic compounds. Citation:

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Dissociation rate of hot benzene

Cited by 78 publications

References 29 publications

Determinations of Intermediate Neutral Species in Hydrocarbon Discharge Plasma

Determinations of Intermediate Neutral Species in Hydrocarbon Discharge Plasma

Formation and distribution of benzene on Titan

An unidentified emission in Titan's upper atmosphere

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