Primary quantum yields in photodissociation of isopropyl nitrite

Ludwig, Barbara E.; McMillan, G. R.

doi:10.1021/ja01033a008

Cited by 13 publications

(13 citation statements)

References 5 publications

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“…The latter is known as an important step in the reduction of nitric oxide in the combustion of alkyl nitrates and nitrites, and it is of relevance to the atmospheric chemistry of CH 3 O which is produced in the oxidation of CH 4 . The existence of this disproportionation reaction has been further confirmed in investigations on the reactions of the radicals ethoxy ,− and isopropoxy − with NO: Finally it is noted that in the context of the present study, we have also investigated the photodissociation of homogeneous ethyl nitrite clusters [C 2 H 5 ONO] n . We found HNO(X̃ 1 A‘) as a cluster reaction product analogous to [CH 3 ONO] n which further corroborates the cluster cage mechanism leading via disproportionation to the formation of HNO.…”

Section: Discussionsupporting

confidence: 58%

Photoinduced Bimolecular Reactions in Homogeneous [CH₃ONO]_nClusters

and

Huber

1997

J. Phys. Chem. A

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The photodissociation of homogeneous methyl nitrite clusters, [CH3ONO] n with n ≈ 400−1000, was investigated in a supersonic jet using excitation mainly at 365 nm, which corresponds to S 0 → S 1 (nπ*) excitation in the monomer. Besides the two types of NO(X̃2II) photofragment distributions, a rotationally relaxed one (T rot ∼ 250 K) and a nonthermally “hot” one (〈J‘‘〉 = 35.5) which result from the primary dissociation step CH3ONO → CH3O + NO of cluster-bound CH3ONO, we observed the products HNO(X̃A‘) and H2CO(X̃1A1) by state-selected LIF spectroscopy. Their product−yield excitation spectra and their formation dependence on the backing pressure revealed that HNO and H2CO originate exclusively from cluster photodissociation and not from primary photodissociation of the monomer. The mechanism of their formation was found to be the disproportionation reaction of the primary photofragments, CH3O + NO → HNO + H2CO, mediated by caging of the cluster environment. The fragments collide with, and recoil at, the solvent shell followed by subsequent recombination, disproportionation, or escape from the evaporating solvent cage. The present results are consistent with previous findings on the photolysis of isolated CH3ONO molecules in solid noble gas matrices where exclusively the products HNO and H2CO were found.

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Section: Discussionsupporting

confidence: 58%

Photoinduced Bimolecular Reactions in Homogeneous [CH₃ONO]_nClusters

and

Huber

1997

J. Phys. Chem. A

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“…The fraction of 'hot' alkoxy radicals estimated from these plots was of the order of B10%, with a hint of an increase with temperature. These results can be compared with the work of McMillan and co-workers [38][39][40] on the photolysis of t-butyl, t-pentyl and isopropyl nitrites at 366 nm where r5% of the alkoxy radicals were reported to be produced with energies above the barrier to decomposition. In order to obtain the ratio k 7 /k 6 in a thermally equilibrated system, the slopes of the plots of Fig.…”

Section: Resultsmentioning

confidence: 82%

A temperature-dependent relative-rate study of the OH initiated oxidation of n-butane: The kinetics of the reactions of the 1- and 2-butoxy radicals

Cassanelli¹,

Johnson

Cox³

2005

Phys. Chem. Chem. Phys.

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The kinetics of the reactions of 1-and 2-butoxy radicals have been studied using a slow-flow photochemical reactor with GC-FID detection of reactants and products. Branching ratios between decomposition, CH3CH(O*)CH2CH3 --> CH3CHO + C2H5, reaction (7), and reaction with oxygen, CH3CH(O*)CH2CH3+ O2 --> CH3C(O)C2H5+ HO2, reaction (6), for the 2-butoxy radical and between isomerization, CH3CH2CH2CH2O* --> CH2CH2CH2CH2OH, reaction (9), and reaction with oxygen, CH3CH2CH2CH2O* + O2 --> C3H7CHO + HO2, reaction (8), for the 1-butoxy radical were measured as a function of oxygen concentration at atmospheric pressure over the temperature range 250-318 K. Evidence for the formation of a small fraction of chemically activated alkoxy radicals generated from the photolysis of alkyl nitrite precursors and from the exothermic reaction of 2-butyl peroxy radicals with NO was observed. The temperature dependence of the rate constant ratios for a thermalized system is given by k7/k6= 5.4 x 10(26) exp[(-47.4 +/- 2.8 kJ mol(-1))/RT] molecule cm(-3) and k9/k8= 1.98 x 10(23) exp[(-22.6 +/- 3.9 kJ mol(-1))/RT] molecule cm(-3). The results agree well with the available experimental literature data at ambient temperature but the temperature dependence of the rate constant ratios is weaker than in current recommendations.

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“…OH radicals were generated from the photolysis of isopropyl nitrite (IPN, Karl Industries, Ohio) in a mixture of N 2 and air (Ultrapure Air, Scott-Marrin, total hydrocarbons as CH 4 o 0.01 ppm; CO o 0.01 ppm; NO x o 0.001 ppm; SO 2 o 0.001 ppm), summarized in reactions 1-3: [30][31][32][33][34] (CH 3 ) 2 CHONO + hn -(CH 3 ) 2 CHO + NO…”

Section: Oh Generationmentioning

confidence: 99%