Evidence for the dominance of collision-induced intersystem crossing in collisions of 1CH2 with O2 and a determination of the H atom yields from 3CH2+O2, using time-resolved detection of H formation by vuvLIF

Blitz, Mark A.; McKee, Kenneth W.; Pilling, Michael J.; Seakins, Paul W.

doi:10.1016/s0009-2614(03)00393-2

Cited by 26 publications

(23 citation statements)

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“…Examples of such CIISC fractional channel yields include 0:10 þ0:10 À0:04 for 1 CH 2 + H 2 [5], 0.1 for 1 CH 2 + CH 4 [3,6], and 0.22 for 1 CH 2 + C 2 H 2 [7]. Parallel measurements for 1 CH 2 + O 2 , by contrast, have demonstrated unit efficiency for CIISC [8,9].…”

Section: Introductionmentioning

confidence: 99%

The effect of temperature on collision induced intersystem crossing in the reaction of 1CH2 with H2

Blitz

Choi

Kovács

et al. 2005

Proceedings of the Combustion Institute

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Section: Introductionmentioning

confidence: 99%

The effect of temperature on collision induced intersystem crossing in the reaction of 1CH2 with H2

Blitz

Choi

Kovács

et al. 2005

Proceedings of the Combustion Institute

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“…For the reaction between 1 CH2 and O2, relaxation has been shown to be the only loss process on timescales applicable to this work (Blitz et al, 2003;Hancock and Haverd, 2003). This is reasonably assumed to be the case over the temperature range employed in this study, as evidenced by the fact that the removal rate of 1 CH2 with O2 over the temperature range of 43 -298 K (Douglas et al, 2018), remains over an order of magnitude faster than the H atom production rates observed in this study (Table II).…”

Section: Ch2 + O2 3 Ch2 + O2 (R18)mentioning

confidence: 96%

“…For the reaction of 3 CH2 with O2 (R19), there have been four room temperature values reported by Blitz et al (2003), Darwin et al (1989), Alvarez and Moore (1994) , and Hancock and Haverd (2003). The reaction was studied by Blitz et al (2003) using a very similar procedure to that used in this work, while two of the other studies used laser flash photolysis of ketene at 351 nm to produce ground state 3 CH2, and monitored the reaction by detecting changes in the absorbance of either the 3 CH2 reactant (Darwin et al, 1989) or the CO product (Alvarez and Moore, 1994). Hancock and Haverd (2003) used time-resolved Fourier transform emission spectroscopy to monitor products from the reaction, with 3 CH2 also being produced by 351 nm photolysis of ketene.…”

Section: Kineticsmentioning

confidence: 99%

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Low temperature studies of the rate coefficients and branching ratios of reactive loss vs quenching for the reactions of 1CH2 with C2H6, C2H4, C2H2

Douglas

Blitz

Feng

et al. 2019

Icarus

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The kinetics of the reactions of the first excited state of methylene, 1 CH2, with C2H2, C2H4, and C2H6, have been measured over the temperature range 43-298 K by pulsed laser photolysis, monitoring 1 CH2 removal by laser induced fluorescence. Low temperatures were obtained using a pulsed Laval expansion (43-134 K), while a slow flow reaction cell was used for temperatures of 160 K and above. The rate coefficients for the reactions with C2H2, C2H4, and C2H6, all showed a strong negative temperature dependence. In combination with other literature data, the coefficients can be parameterized as: kC 2 H 2 (43 ≤ T/K ≤ 298) = (3.22 ± 0.15) × 10-10 × (T/298) (-0.394 ±0.066) kC 2 H 4 (43 ≤ T/K ≤ 298) = (2.16 ± 0.14) × 10-10 × (T/298) (-0.612 ±0.089) kC 2 H 6 (43 ≤ T/K ≤ 298) = (1.78 ± 0.10) × 10-10 × (T/298) (-0.545 ±0.078) Branching ratios for reactive removal of 1 CH2 vs quenching to ground state were also determined for all three colliders and for H2 and CH4, at temperatures between 100 and 298 K. The values measured show that the dominant removal process of 1 CH2 by H2, C2H2, and C2H4, changes from reactive removal to quenching to ground state 3 CH2 as the temperature decreases from 298 K to 100 K, while for CH4 and C2H6, reactive removal drops from around 85 % to around 55 %. The impacts of the new measurements for Titan's atmosphere are examined using a 1D chemistry and transport model. A significant increase (~25%) in the mixing ratio of benzene between 500 and 1550 km is calculated, due to the increased production of C3H3 from the reaction of 1 CH2 with C2H2.

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Dynamics of the CH₃ + OH reaction

Ree

Kim

Shin

2011

Int J of Chemical Kinetics

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We study dynamics of the CH 3 + OH reaction over the temperature range of 300-2500 K using a quasiclassical method for the potential energy composed of explicit forms of short-range and long-range interactions. The explicit potential energy used in the study gives minimum energy paths on potential energy surfaces showing barrier heights, channel energies, and van der Waals well, which are consistent with ab initio calculations. Approximately, 20% of CH 3 + OH collisions undergo OH dissociation in a direct-mode mechanism on a subpicosecond scale (<50 fs) with the rate coefficient as high as ∼10 −10 cm 3 molecule −1 s −1 . Less than 10% leads to the formation of excited intermediates CH 3 OH † with excess vibrational energies in CO and OH bonds. CH 3 OH † stabilizes to CH 3 OH, redissociates back to reactants, or forms one of various products after intramolecular energy redistribution via bond dissociation and formation on the time scale of 50-200 fs. The principal product is 1 CH 2 (k CH 2 being ∼10 −11 ), whereas ks for CH 2 OH, CH 2 O, and CH 3 O are ∼10 −12 . The minor products are HCOH and CH 4 (k ∼10 −13 ). The total rate coefficient for CH 3 + OH → CH 3 OH † → products is ∼10 −11 and is weakly dependent on temperature. C

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Evidence for the dominance of collision-induced intersystem crossing in collisions of 1CH2 with O2 and a determination of the H atom yields from 3CH2+O2, using time-resolved detection of H formation by vuvLIF

Cited by 26 publications

References 23 publications

The effect of temperature on collision induced intersystem crossing in the reaction of 1CH2 with H2

The effect of temperature on collision induced intersystem crossing in the reaction of 1CH2 with H2

Low temperature studies of the rate coefficients and branching ratios of reactive loss vs quenching for the reactions of 1CH2 with C2H6, C2H4, C2H2

Dynamics of the CH₃ + OH reaction

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Evidence for the dominance of collision-induced intersystem crossing in collisions of 1CH2 with O2 and a determination of the H atom yields from 3CH2+O2, using time-resolved detection of H formation by vuvLIF

Cited by 26 publications

References 23 publications

The effect of temperature on collision induced intersystem crossing in the reaction of 1CH2 with H2

The effect of temperature on collision induced intersystem crossing in the reaction of 1CH2 with H2

Low temperature studies of the rate coefficients and branching ratios of reactive loss vs quenching for the reactions of 1CH2 with C2H6, C2H4, C2H2

Dynamics of the CH3 + OH reaction

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Dynamics of the CH₃ + OH reaction