Quantum yield of chlorine-atom formation in the photodissociation of chlorine peroxide (ClOOCl) at 308 nm

Molina, Mario J.; Colussi, A. J.; Molina, Luisa T.; Schindler, R. N.; Tso, Tai‐Ly

doi:10.1016/0009-2614(90)85275-h

Cited by 60 publications

(49 citation statements)

References 9 publications

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“…This result confirms earlier work, where the quantum yield for Cl formation is reported to be unity. 12 The present results corroborate the conclusions deduced from previous works and reduce the error limit of the primary quantum yield of ClOOCl photolysis. Model simulations yield significant differences for the ozone mixing ratio considering (a) ClOOCl decays exclusively via eq 2, i.e., γ Cl ) 1.0, and (b) γ Cl ) 0.9 and γ ClO ) 0.1.…”

Section: Resultssupporting

confidence: 92%

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Ultraviolet Photolysis of the ClO Dimer

Plenge¹,

Flesch²,

Kühl³

et al. 2004

J. Phys. Chem. A

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Photodissociation of the ClO dimer (ClOOCl) is studied in the ultraviolet regime (250 and 308 nm) under collision-free conditions. The primary photolysis products are probed by photoionization mass spectrometry. At both photolysis wavelengths, exclusively the formation of 2Cl + O 2 is observed, corresponding to a primary quantum yield γ Cl near unity. Considering the error limit of the experimental results one obtains γ Cl g 0.98 at 250 nm and γ Cl g 0.90 at 308 nm, respectively. At both photolysis wavelengths the pathway yielding ClO is not observed, corresponding to γ ClO e 0.02 at 250 nm and γ ClO e 0.10 at 308 nm. Sensitivity studies of these results with respect to ozone depletion in the stratosphere regarding photochemically induced ozone loss are discussed using model simulations. These simulations suggest that a change of γ Cl from 1.0 to 0.9 leads to a reduction of polar ozone loss of ∼5%.

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Section: Resultssupporting

confidence: 92%

“…12,13 This is accomplished by considering the detection limits of both cations. The estimate of the detection limits is based on the cation signals strengths that are measured as voltage pulses by a digital oscilloscope, where the signals are loaded into 50 Ω.…”

Section: Resultsmentioning

confidence: 99%

Ultraviolet Photolysis of the ClO Dimer

Plenge¹,

Flesch²,

Kühl³

et al. 2004

J. Phys. Chem. A

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“…Among the various classes of compounds present in the troposphere, unsaturated hydrocarbons are unique in exhibiting signifi-acids. The kinetics and mechanisms of the gas-phase reactions of ozone with organic compounds have been comprehensively reviewed by Atkinson and Carter [3]. Most studies on the reactions of ozone and alkenes have been limited to room temperature, the primary purpose being to elucidate the role of these reactions in atmospheric pollution.…”

Section: Introductionmentioning

confidence: 99%

Reactions of Ozone with Unsaturated Organic Compounds

Treacy¹,

Hag²,

O'Farrell³

et al. 1992

Ber Bunsenges Phys Chem

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The basis 3df2df in Table 1 again contains one set of $functions on all heavy atoms. Second row atoms carry three sets of &functions but first row atoms only two. When this basis set is used instead of 6-31 lG(2dJp) the atomization energies of C10, OC10, and ClOO are all in acceptable agreement with experiment.The basis 3df2df has been applied to two further test molecules and to the C103-isomers. For all species in Table 1 but ClOCl the deviation is less than 5 kcalfmol.The G1 calculations on C103-isomers were started with geometry optimizations on the HF/6-31G*-and MP2f6-31G*-levels of theory. All three supposed isomers, C1000, OC100, and sym-C103 were found as minima [9] on the potential energy hypersurface. The GI total energy calculations using the basis set described above gave heats of formation of 41, 58, and 48 kcalfmol, respectively.From these ab initio calculations it appears that ClOOO might be considered as an intermediate in reaction (1). Since it is a real minimum on the potential energy hypersurface, there must exist a barrier for the exothermic dissociation of ground state ClOOO into C10 and 02.The work was supported in part by the BMFT, Bonn, withinThe authors acknowledge access to the facilities of the Hochstproject 0744120 0.leistungsrechenzentrum Julich. References Howard SidebottomUniversity College Dublin, Ireland Chemical Kinetics f Elementary Reactions f RadicalsRate constants for the gas-phase reactions of ozone with a series of alkenes have been determined using a conventional static system. Ozone loss was monitored in excess of the hydrocarbon and rate data measured at 1 atmosphere total pressure over the temperature range 240-324 K. The Arrhenius parameters obtained are discussed in terms of structure-reactivity relationships. Product studies have been carried out for the reaction of O3 with the conjugated dienes, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene) and 2,3-dimethyl-1,3-butadiene in air. The results provide information on the decomposition pathways for the primary ozonides and the relative importance of ozone addition to the two doublebonds in isoprene.cant reactivity towards ozone as well as towards hydroxyl and nitrate radicals. Numerous potentially important roles of the ozone-alkene reaction have been recognized since these reactions can provide mutual sinks for both ozone and alkenes and concomitantly serve as sources of partially oxidised compounds e. g. CO, aldehydes, ketones and organic

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“…These observations are in agreement with the results of quantum mechanical calculations (McGrath et al [508,509]; Jensen and Odershede [379]; Stanton et al [750]). Molina et al [548] reported a quantum yield of approximately unity (1.03 ± 0.12) for the Cl + ClOO pathway from a flash photolysis study at 308 nm, in which the yield of Cl atoms was measured using time-resolved atomic resonance fluorescence. These results are in agreement with the steady-state photolysis study of Cox and Hayman [190].…”

Section: -95mentioning

confidence: 99%

“…O + CS. The room temperature recommendation is an average of the rate constants determined by Slagle et al [1210], Bida et al [135], Lilenfeld and Richardson [827], and Hancock and Smith [548]. The temperature dependence is that of Lilenfeld and Richardson, with the A-factor adjusted to yield the recommended value of k(298 K).…”

Section: -96mentioning

confidence: 99%