Spectroscopic observation of the methylene(~a1A1) radical in the reaction of acetylene with oxygen atoms

Abstract

acetone molecular ions retain large amounts of internal energy for more than 30 /us after formation by electron impact. (2) These highly excited ions are the dominant CID reactants at such low collision energies. (3) These low-energy (0.45-and 0.65-eV) collisions trigger the release (E -* T) of about 2.9 eV of stored energy into the recoil of the acetone ion and the collider He atom. With reference to the initial ion beam direction, the acetone ions are backward scattered and He atoms are forward scattered in the CM coordinate frame. (4) The recoiling acetone molecular ion rapidly dissociates into acetyl ion and methyl radical with low kinetic energy of separation. We infer from these observations that the collision process triggers the A -X conversion of the acetone molecular ion with the release of most (perhaps all) of the stored electronic energy as translational energy. The vibrationally excited ion then dissociates from the ground-state hypersurface. Our continuing research on polyatomic ion CID dynamics will address the question whether electronically excited states are also important intermediates at higher collision energies.

Identification of the Sequence CH(2Π) + C2H2 → C3H2 + H (and C3H + H2) Followed by C3H2 + O → C2H + HCO (or H + CO) as C2H Source in C2H2/O/H Atomic Flames

“…Including the known C 2 H 2 plus O reaction mechanism, leading to the formation of CH( 2 Π), [20][21][22][23][24][25][26][27][28][29][30][31][32][33]40,41,56 the overall mechanism for C 2 H production can be schematized as follows:…”

“…27 Hydrogen atoms are known to react very rapidly with both primary products of reaction 1, HCCO, 22,28 and CH 2 ( 3 B 1 ). 25, 31 The CH 2 ( 3 B 1 ) + H reaction (r5) produces CH( 2 Π), which exhibits a similar high reactivity toward closed-shell molecules as does CH 2 ( 1 A 1 ). 25, 31 The CH 2 ( 3 B 1 ) + H reaction (r5) produces CH( 2 Π), which exhibits a similar high reactivity toward closed-shell molecules as does CH 2 ( 1 A 1 ).…”

Soft electron impact ionization in crossed molecular beam reactive scattering: The dynamics of the O(3P)+C2H2 reaction

“…The reaction plays an important role as intermediate in soot formation in flames, [19][20][21][22] and is also thought to be responsible of prompt CO 2 formation in acetylene flames. 23 For the theoretical modeling of combustion systems an accurate branching ratio of reaction ͑1͒ is needed.…”

Absolute Rate Coefficient of the HCCO + NO Reaction over the Range T = 297−802 K

“…14 Of these reactions, those involving the ketenyl radical, HCCO, play a central role, 14 particularly the rapid reaction of ketenyl with atomic hydrogen, 15,16 which leads to highly reactive CH 17 and CH 2 (ã 1 A 1 ); 18 These radicals are known to undergo rapid reactions with many hydrocarbons, notably C 2 H 2 , [19][20][21][22] leading to higher unsaturated hydrocarbons, which are the building blocks of polycyclic aromatic hydrocarbons. 23,24 In combustion, HCCO is formed mainly by oxidation of ethyne, [25][26][27][28][29] and thought to be removed mainly by reaction with O 2 , H, O, OH, and NO.…”