193 nm photodissociation of acetylene

Balko, Barbara A.; Zhang, J.; Lee, Yuan T.

doi:10.1063/1.460130

Cited by 93 publications

(78 citation statements)

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“…It is important to stress that the benzene molecule (C 6 H 6 ) [44][45][46] is present in the atmosphere of Titan along with highly reactive ethynyl radicals (C 2 H); the latter are predominantly formed from the solar ultraviolet photolysis of acetylene at wavelengths below 200 nm. [47][48][49][50][51] Therefore, the present crossed beam study of the perdeutero variant of the ethynyl radical with benzene is aimed to extract the underlying chemical dynamics together with potential reaction intermediates and the final reaction product under single collision conditions to shed light if the phenylacetylene molecule can be formed via a barrierless reaction of benzene with the ethynyl radical.…”

Section: Introductionmentioning

confidence: 99%

Crossed Molecular Beam Study on the Formation of Phenylacetylene and Its Relevance to Titan’s Atmosphere

et al. 2010

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The crossed molecular beam experiment of the deuterated ethynyl radical (C 2 D; X 2 Σ + ) with benzene [C 6 H 6 (X 1 A 1g )] and its fully deuterated analog [C 6 D 6 (X 1 A 1g )] was conducted at a collision energy of 58.1 kJ mol -1 . Our experimental data suggest the formation of the phenylacetylene-d 6 via indirect reactive scattering dynamics through a long-lived reaction intermediate; the reaction is initiated by a barrierless addition of the ethynyl-d 1 radical to benzene-d 6 . This initial collision complex was found to decompose via a tight exit transition state located about 42 kJ mol -1 above the separated products; here, the deuterium atom is ejected almost perpendicularly to the rotational plane of the decomposing intermediate and almost parallel to the total angular momentum vector. The overall experimental exoergicity of the reaction is shown to be 121 ( 10 kJ mol -1 ; this compares nicely with the computed reaction energy of -111 kJ mol -1 . Even though the experiment was conducted at a collisional energy higher than equivalent temperatures typically found in the atmosphere of Titan (94 K and higher), the reaction may proceed in Titan's atmosphere as it involves no entrance barrier, all transition states involved are below the energy of the separated reactants, and the reaction is exoergic. Further, the phenylacetylene was found to be the sole reaction product.

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Section: Introductionmentioning

confidence: 99%

Crossed Molecular Beam Study on the Formation of Phenylacetylene and Its Relevance to Titan’s Atmosphere

et al. 2010

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“…The use of this machine in high resolution photodissociation studies has been described previously [29]. The experimental protocol is the same as for the previous acetylene photodissociation experiments [29], the only difference being that all TOF spectra were taken without the skimmer.…”

Section: Experimentmentioning

confidence: 99%

“…However, based on the analogous C 2 H 2 photodissociation 9 experiments [29,31], this effect should only contribute a maximum of 2 kcal/mole. Since the P(E T ) threshold is much greater than 64 kcal/mole, the fast tail must be attributed to acetylene formation.…”

Section: Comparison Of Atomic and Molecular Channelsmentioning

confidence: 99%

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Photodissociation of ethylene at 193 nm

Balko

Zhang

Lee

1992

The Journal of Chemical Physics

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The photodissociation of ethylene at 193 nm was studied by measuring the product translational energy distributions for the H+C2H3 and H2+C2H2 channels. In agreement with previous workers, it was determined that atomic and molecular elimination occur in relatively equal amounts. Using 1,1 D2CCH2 and 1,2 cis HDCCDH, it was shown that both acetylene and vinylidene are formed and that the acetylene/vinylidene ratio is approximately 2/3 in the molecular elimination. This H2 elimination channel has a translational energy distribution peaked at around 20 kcal/mol, indicating that it is a concerted process with a substantial exit barrier. It was found that the H atom elimination channel is best described as a simple bond rupture occurring after internal conversion of the electronically excited molecule to the vibrationally excited ground state ethylene. Some of the primary C2H3 product has sufficient internal energy to spontaneously decompose to H+HC≡CH. At higher laser intensity a large fraction of the C2H3, however, absorbs another photon and fragments to H+H2C=C: (1A1 and 3B2).

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“…[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] This ab initio quantum chemistry study of neutral-radical reactions with unsaturated hydrocarbons consists of two fundamental parts. The first is an investigation of the reaction mechanism, derived from quantum chemical calculations of the ethynyl or cyano addition reaction to the unsaturated hydrocarbon.…”

Section: List Of Tablesmentioning

confidence: 99%

Ab Initio Quantum Chemical Studies on Neutral-Radical Reactions of Ethynyl (C2H) and Cyano (CN) with Unsaturated Hydrocarbons

Jamal¹

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193 nm photodissociation of acetylene

Cited by 93 publications

References 43 publications

Crossed Molecular Beam Study on the Formation of Phenylacetylene and Its Relevance to Titan’s Atmosphere

Crossed Molecular Beam Study on the Formation of Phenylacetylene and Its Relevance to Titan’s Atmosphere

Photodissociation of ethylene at 193 nm

Ab Initio Quantum Chemical Studies on Neutral-Radical Reactions of Ethynyl (C2H) and Cyano (CN) with Unsaturated Hydrocarbons

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