Temperature dependence of the collisional deactivation of I (2P12) by I2 and O2 from 300 to 600 K

Burde, D. H.; Yang, Tiankai; McFarlane, R. A.

doi:10.1016/0009-2614(93)85168-n

Cited by 18 publications

(7 citation statements)

References 21 publications

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“…For this reason, O 2 , an efficient quencher of I* was added to most experiments, typically at the 1-3 Torr level. As the quenching rate coefficient, (k 9 ) is E4 Â 10 À11 cm 3 molecule À1 s À1 , 17,18 the lifetime of I( 2 P 1/2 ) is just a few ms for conversion to ground state I, which is considerably shorter than the chemical lifetime of I due to reactions (R1), (R6) or (R7).…”

Section: Resultsmentioning

confidence: 99%

A laser photolysis–resonance fluorescence study of the reactions: I + O₃→ IO + O₂, O + I₂→ IO + I, and I + NO₂+ M → INO₂+ M at 298 K

Tucceri

Dillon

Crowley

2005

Phys. Chem. Chem. Phys.

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Laser flash photolysis coupled to resonance-fluorescence detection of I atoms was used to measure the rate coefficients for the reactions: I + O3 --> IO + O2 (R1), O + I2 --> IO + I (R6) and I + NO2 + M --> INO2 + M (R7). All experiments were conducted under pseudo first-order conditions, and the accuracy of the results was enhanced by online determination of reagent concentrations by optical absorption. Bimolecular rate coefficients for reactions (R1) and (R6) were determined to be k1 = (1.28 +/- 0.06) x 10(-12) and k6 = (1.2 +/- 0.1) x 10(-10) cm3 molecule(-1) s(-1) at 298 +/- 2 K, independent of pressure. Rate coefficients for the termolecular reaction (R7), also at 298 +/- 2 K, were found to be in the falloff region between 3rd and 2nd order behaviour and, when combined with other datasets obtained at higher and lower pressures, were adequately described by a simplified Troe function with the parameters: k7,0 (He, 330 K) = 1.48 x 10(-31) cm6 molecule(-2) s(-1), F(C) (He) = 0.43, and k7, infinity = 1.1 x 10(-10) cm3 molecule(-1) s(-1) for He as bath gas. In N2 (or air) the following parameters were obtained k7,0 (N2, 300 K) = 3.2 x 10(-31) cm6 molecule(-2) s(-1), F(C) ( N2) = 0.48, with k7, infinity set to 1.1 x 10(-10) cm3 molecule(-1) s(-1) as obtained from analysis of the falloff curve obtained in He.

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Section: Resultsmentioning

confidence: 99%

A laser photolysis–resonance fluorescence study of the reactions: I + O₃→ IO + O₂, O + I₂→ IO + I, and I + NO₂+ M → INO₂+ M at 298 K

Tucceri

Dillon

Crowley

2005

Phys. Chem. Chem. Phys.

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“…CF 3 I photolysis resulting in an excited state iodine atom occurs primarily at λ < 300 nm. , However, the obvious reactions, are endothermic given the currently accepted values for the enthalpies of formation for IO and HI . Addition of O 2 would deactivate I* produced by CF 3 I photolysis through the near resonant electronic−electronic energy transfer process where k 7 = 4 × 10 -11 cm 3 molecule -1 s -1 . O 2 also reacts with CF 3 ( k 8 296 K, 25 Torr) = ∼3 × 10 -12 cm 3 molecule -1 s -1 .…”

Section: Discussionmentioning

confidence: 99%

Rate Coefficients for the OH + CF₃I Reaction between 271 and 370 K

2000

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The rate coefficient, k 1, for the reaction OH + CF3I → products was measured under pseudo-first-order conditions in hydroxyl radical, OH. OH temporal profiles were monitored by laser-induced fluorescence (LIF), and CF3I concentrations were determined by UV/Visible absorption. We determined k 1 (T) to be (2.10 ± 0.80) × 10-11 exp[−(2000 ± 140)/T] cm3 molecule-1 s-1, over the temperature range 271 to 370 K. The quoted uncertainties are 2σ (95% confidence limits, σA = AσlnA). Previous measurements of k 1(T) are compared with our values, and possible reasons for the discrepancies are discussed. The heat of formation of HOI is deduced to be less than −16 kcal mole-1, if the products of reaction 1 are mostly HOI and CF3. These measurements support the earlier conclusion that the reaction of OH with CF3I plays a negligibly small role in the atmospheric removal of CF3I.

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“…Extensive studies have been carried out measuring quenching efficiencies of several compounds on the Temperature dependence studies [9,10] (case b) have been carried out in some systems and might provide some insight into the interaction involved in the energy transfer process although, as expected, "weak" temperature dependencies have been reported so far and it is not easy to interpret them for complex acceptor molecules [11].…”

Section: Introductionmentioning

confidence: 96%

Quenching of I(2P�) by R-OH compounds. Influence of the alkyl group on the quenching efficiency

Chiappero

Badini

Argüello

1997

Int. J. Chem. Kinet.

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I* emission. These have been extended to many systems to understand the mechanism involved in energy transfer processes. This problem has been tackled using several approaches: (a) Direct measurement of state-to-state E-v rate constants; (b) Temperature dependence of the bulk or overall quenching rate constants; (c) Isotope effects on the observed quenching rate constants; and (d) study of the quenching efficiencies of a "family" of compounds.Although the first approach is the most satisfactory and direct, only in few cases is it experimentally achievable. Few systems (HF, H 2 , and H 2 O) [5][6][7][8] have been studied directly (case a) because of the complexity added by the acceptor intramolecular energy redistribution which grows with the number of vibrational degrees of freedom. Based on the kinetic analysis of the system, state-to-state energy transfer studies are limited up to triatomic acceptor molecules. INTRODUCTIONThe study of the electronically excited iodine atom, I ( 2 P 1/2 ) (hereafter called I*) constitutes a case example of a system which can undergo electronic to vibrational-rotational energy transfer. The I* is only about 0.92 eV above the ground state and this energy excess hardly contributes to the already low reactivity of the iodine atom in gas phase. Actually, there are few systems in which reactive quenching of I* is present (i.e., interhalogens, ozone) [1 -4].Extensive studies have been carried out measuring quenching efficiencies of several compounds on the ABSTRACTThe deactivation of I( 2 P 1/2 ) by R-OH compounds (R ϭ H, C n H 2nϩ1 ) was studied using time-resolved atomic absorption at 206.2 nm. The second-order quenching rate constants determined for H 2 O, CH 3 OH, C 2 H 5 OH, n-C 3 H 7 OH, i-C 3 H 7 OH, n-C 4 H 9 OH, i-C 4 H 9 OH, s-C 4 H 9 OH, t-C 4 H 9 OH, are respectively, 2.4 Ϯ 0.3 ϫ 10 Ϫ12 , 5.5 Ϯ 0.8 ϫ 10 Ϫ12 , 8 Ϯ 1 ϫ 10 Ϫ12 , 10 Ϯ 1 ϫ 10 Ϫ12 , 10 Ϯ 1 ϫ 10 Ϫ12 , 11.1 Ϯ 0.9 ϫ 10 Ϫ12 , 9.8 Ϯ 0.9 ϫ 10 Ϫ12 , 7.1 Ϯ 0.7 ϫ 10 Ϫ12 , and 4.1 Ϯ 0.4ϫ 10 Ϫ12 cm 3 molec Ϫ1 s Ϫ1 at room temperature. It is believed that a quasi-resonant electronic to vibrational energy transfer mechanism accounts for most of the features of the quenching process. The influence of the alkyl group and its role in the total quenching rate is also discussed.

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Temperature dependence of the collisional deactivation of I (2P12) by I2 and O2 from 300 to 600 K

Cited by 18 publications

References 21 publications

A laser photolysis–resonance fluorescence study of the reactions: I + O₃→ IO + O₂, O + I₂→ IO + I, and I + NO₂+ M → INO₂+ M at 298 K

A laser photolysis–resonance fluorescence study of the reactions: I + O₃→ IO + O₂, O + I₂→ IO + I, and I + NO₂+ M → INO₂+ M at 298 K

Rate Coefficients for the OH + CF₃I Reaction between 271 and 370 K

Quenching of I(2P�) by R-OH compounds. Influence of the alkyl group on the quenching efficiency

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Temperature dependence of the collisional deactivation of I (2P12) by I2 and O2 from 300 to 600 K

Cited by 18 publications

References 21 publications

A laser photolysis–resonance fluorescence study of the reactions: I + O3→ IO + O2, O + I2→ IO + I, and I + NO2+ M → INO2+ M at 298 K

A laser photolysis–resonance fluorescence study of the reactions: I + O3→ IO + O2, O + I2→ IO + I, and I + NO2+ M → INO2+ M at 298 K

Rate Coefficients for the OH + CF3I Reaction between 271 and 370 K

Quenching of I(2P�) by R-OH compounds. Influence of the alkyl group on the quenching efficiency

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A laser photolysis–resonance fluorescence study of the reactions: I + O₃→ IO + O₂, O + I₂→ IO + I, and I + NO₂+ M → INO₂+ M at 298 K

A laser photolysis–resonance fluorescence study of the reactions: I + O₃→ IO + O₂, O + I₂→ IO + I, and I + NO₂+ M → INO₂+ M at 298 K

Rate Coefficients for the OH + CF₃I Reaction between 271 and 370 K