Relative rate constants for removal of vibrationally excited OH(X2πi)v=9 by some small molecules at room temperature

Finlayson-Pitts, B. J.; Toohey, D. W.; Ezell, M. J.

doi:10.1002/kin.550150206

Cited by 13 publications

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“…Under local thermodynamic equilibrium conditions, the fraction of vibrationally excited molecules is in the order of magnitude of only 10 −8 . Literature on the rate coefficients involving Reaction (R1) for vibrationally excited OH is quite sparse and in partial disagreement (Coltharp et al, 1971;Worley et al, 1972;Finlayson-Pitts et al, 1983;Varandas and Zhang, 2001 and references therein). For our study, rate coefficients as a function of temperature and OH vibrational level as suggested by Varandas and Zhang (2001) are used.…”

Section: Introductionmentioning

confidence: 99%

Do vibrationally excited OH molecules affect middle and upper atmospheric chemistry?

et al. 2010

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Abstract. Except for a few reactions involving electronically excited molecular or atomic oxygen or nitrogen, atmospheric chemistry modelling usually assumes that the temperature dependence of reaction rates is characterized by Arrhenius' law involving kinetic temperatures. It is known, however, that in the upper atmosphere the vibrational temperatures may exceed the kinetic temperatures by several hundreds of Kelvins. This excess energy has an impact on the reaction rates. We have used upper atmospheric OH populations and reaction rate coefficients for OH(v = 0...9)+O 3 and OH(v = 0...9)+O to estimate the effective (i.e. population weighted) reaction rates for various atmospheric conditions. We have found that the effective rate coefficient for OH(v = 0...9)+O 3 can be larger by a factor of up to 1470 than that involving OH in its vibrational ground state only. At altitudes where vibrationally excited states of OH are highly populated, the OH reaction is a minor sink of O x and O 3 compared to other reactions involving, e.g., atomic oxygen. Thus the impact of vibrationally excited OH on the ozone or O x sink remains small. Among quiescent atmospheres under investigation, the largest while still small (less than 0.1%) effect was found for the polar winter upper stratosphere and mesosphere. The contribution of the reaction of vibrationally excited OH with ozone to the OH sink is largest in the upper polar winter stratosphere (up to 4%), while its effect on the HO 2 source is larger in the lower thermosphere (up to 1.5% for polar winter and 2.5% for midlatitude night conditions). For OH(v = 0...9)+O the effective rate coefficients are Correspondence to: T. von Clarmann (thomas.clarmann@kit.edu) lower by up to 11% than those involving OH in its vibrational ground state. The effects on the odd oxygen sink are negative and can reach −3% (midlatitudinal nighttime lowermost thermosphere), i.e. neglecting vibrational excitation overestimates the odd oxygen sink. The OH sink is overestimated by up to 10%. After a solar proton event, when upper atmospheric OH can be enhanced by an order of magnitude, the excess relative odd oxygen sink by consideration of vibrational excitation in the reaction of OH(v = 0...9)+O 3 is estimated at up to 0.2%, and the OH sink by OH(v = 0...9)+O can be reduced by 12% in the thermosphere by vibrational excitation.

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Section: Introductionmentioning

confidence: 99%

Do vibrationally excited OH molecules affect middle and upper atmospheric chemistry?

et al. 2010

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Kinetics of interaction of vibrationally excited OH(X²π_i)_v=9 with simple hydrocarbons at room temperature

Finlayson-Pitts

Toohey

Ezell

1985

Int J of Chemical Kinetics

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Relative rate constants for the removal of vibrationally excited OH in the ninth vibrational level of its ground electronic state [designated hereafter by OH'(9)I by interaction with a series of simple hydrocarbons at room temperature are reported. The reaction of hydrogen atoms with ozone was used to generate OH'(9) in a fast flow discharge system at 1.1 2 0.1 torr total pressure. The decrease in the (9 + 3 band) Meinel band chemiluminescent emission intensity at 626 nm was followed as a function of the concentration of added organic or of a reference deactivator (02), respectively, at a fixed reaction time; these data gave relative rate constants, k f / k ; * , for the removal of OH'(9) by the organic. The relative rate constants determined in this study are as follows: C,H,, 2.7 k 0.2; C,H8, 4.4 k 0.4; n-C,H,,, 7.5 t 0.6; iso-C,H,,, 7.3 k 0.8; n--C,H,,, 10.4 2 0.7; C2Ha, 22.9 2 1.8; C3H6, 43.4 k 1.4; cis-2-C4H,, 47.7 2 3.1; C6&, 29 2 7. (Errors are two standard deviations of the weighted mean of experiments in two flow tubes with different wall coatings and carrier gases.) The implications of the trends in these rate constants for the relative contributions of energy transfer and reaction to the net removal of OH'(9) are discussed.

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Numerical simulation of an optically active medium of an OD-CO2 laser

Myasnikov

Neshchimenko

Tubin

1991

Journal of Engineering Physics

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Relative rate constants for removal of vibrationally excited OH(X²π_i)_v=9 by some small molecules at room temperature

Cited by 13 publications

References 49 publications

Do vibrationally excited OH molecules affect middle and upper atmospheric chemistry?

Do vibrationally excited OH molecules affect middle and upper atmospheric chemistry?

Kinetics of interaction of vibrationally excited OH(X²π_i)_v=9 with simple hydrocarbons at room temperature

Numerical simulation of an optically active medium of an OD-CO2 laser

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Relative rate constants for removal of vibrationally excited OH(X2πi)v=9 by some small molecules at room temperature

Cited by 13 publications

References 49 publications

Do vibrationally excited OH molecules affect middle and upper atmospheric chemistry?

Do vibrationally excited OH molecules affect middle and upper atmospheric chemistry?

Kinetics of interaction of vibrationally excited OH(X2πi)v=9 with simple hydrocarbons at room temperature

Numerical simulation of an optically active medium of an OD-CO2 laser

Contact Info

Product

Resources

About

Relative rate constants for removal of vibrationally excited OH(X²π_i)_v=9 by some small molecules at room temperature

Kinetics of interaction of vibrationally excited OH(X²π_i)_v=9 with simple hydrocarbons at room temperature