Dynamics of the reaction O(1D2)+H2→OH(X 2Π,v″=2,3)+H: Full characterization of product energetics

Cleveland, Cheryl B.; Jursich, Gregory; Trolier, M.; Wiesenfeld, J. R.

doi:10.1063/1.451984

Cited by 67 publications

(29 citation statements)

References 38 publications

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“…The general trend in the excitation data is similar to that reported by others [e.g., Mikulecky and Cericke, 1992;Smith and Butler, 1980;Butler et al, 1986;Cleveland et al, 1987] for this range of rotational levels. The excitation rate is found to increase approximately linearly with increasing rotational level and then fall off at total internal energies near the reaction exoergicity.…”

Section: Discussionsupporting

confidence: 76%

Chemistry of Atmospheric Excitation Processes

Caledonia¹,

Oakes²,

Upschulte³

et al. 2002

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Section: Discussionsupporting

confidence: 76%

Chemistry of Atmospheric Excitation Processes

Caledonia¹,

Oakes²,

Upschulte³

et al. 2002

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“…IS ExperimentaP-3,6,16,17 and molecular dynamics simulation studies 8 ,18-24 have demonstrated that the simplest ofthese 0* reactions, that with H2 in Eq. (2), proceeds via insertion of 0* into the H-Hbond to yield HOH, 6,16,17,25 with subsequent decomposition of the chemically activated intermediate leading to production of highly excited OH molecules.…”

Section: Introductionmentioning

confidence: 99%

Full characterization of OH product energetics in the reaction of O(1D2) with hydrocarbons

Park¹,

Wiesenfeld²

1991

The Journal of Chemical Physics

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120

122

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The energetics of the OH(X 2Π, 0≤ν″≤4) product arising from the reaction of O(1D2) with the hydrocarbons CH4, C2H6, C3H8, and C(CH3)4 was fully characterized using laser-induced fluorescence (LIF). The product distribution is in sensible accord with earlier more limited LIF and infrared chemiluminescence studies, and the overall yield of OH decreases dramatically in the case of the heavier hydrocarbons as would be expected if dissociation of the collision intermediate was dominated by rupture of the relatively weak C–C bond. The energetics of the O(1D2)/CH4 reaction suggest that it proceeds via an insertion/elimination reaction, while that of O(1D2) with the heavier hydrocarbons appears to involve two parallel mechanisms. The major channel yields vibrationally and rotationally cool OH; by comparison with abstraction of hydrogen by O(3PJ) which preferentially yields vibrationally excited OH, this channel is associated with dissociation of a long-lived complex. The highly excited component of OH population arises from a prompt dissociation of a collision complex prior to statistical distribution of reaction exothermicity among its internal modes.

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“…Preferential population of Å(A 0 ) states has also been observed for dissociation of water initiated by the chemical reaction ( Butler et al 1986;Cleveland et al 1987;Alexander et al 2004 (Harich et al 2000). Calculations by Dixon (1995) and Dixon et al (1999) addressing these dissociation channels imply that for slow molecular rotation of H 2 O, the Å (A 0 ) states dominate, with the effect being strongest in the limiting case of the nonrotating parent.…”

Section: Discussionmentioning

confidence: 91%

A Comprehensive Study of Infrared OH Prompt Emission in Two Comets. II. Implications for Unimolecular Dissociation of H₂O

Bonev

Mumma

2006

ApJ

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Infrared emission from hydroxyl has been observed in several comets via high-resolution infrared spectroscopy. The principal excitation mechanism for this emission is single-step photolysis of H 2 O, terminating in OH fragments that are both vibrationally and rotationally excited. Recently reported comet data provide quantitative measures of the rotational distribution of OH Ã [X 2 Å; v 0 ¼ 1] for J 0 < 17:5. The measured distributions of relative g-factors for OH ''prompt'' emission, and especially the ratios of the Å(A 00 ) and Å(A 0 ) Ã-doubling components, are remarkably similar for comets C/2000 WM 1 (LINEAR) and C/2004 Q2 (Machholz). We discuss how these results complement ab initio theoretical studies of water dissociation and those done in terrestrial laboratories. (1Y0) and (2Y1) vibrational bands were detected. Paper I discussed the principal excitation mechanism for these lines, namely, photolysis of the parent molecule ( H 2 O) producing OH fragments that are both vibrationally and rotationally excited:The quantum state distribution of the dissociation product (OH Ã ) is governed by the exit channels from the electronically excited dissociative parent state (H 2 O Ã ), whose excitation in turn depends on the UV photon energy (h ) and the initial state population of H 2 O (see Häusler et al. 1987 . 1986). This parameter has been found to vary from $20 to $120 K, depending mainly on the total water production rate in the particular comet. The rotational quantum structure of OH Ã (X 2 Å ) (see Dieke & Crosswhite 1962;Herzberg 1988) causes the rovibrational emission lines to be grouped in ''quadruplets''-series of four lines corresponding to the same value of the quantum number N. 2 Such quadruplets have been observed at IR wavelengths in a number of comets (see Paper I and references therein). Paper I presented calibrated emission efficiencies (equivalent g-factors, measured in OH photons s À1 [H 2 O molecule] À1 ) for OH PE and described their application for quantifying the production of cometary H 2 O: a basic and critical measurement in cometary science. However, the distribution of relative emission efficiencies among the lines in the detected quadruplets has not been addressed until now.In this second paper of this series, we shift the focus from the problem of H 2 O production to that of H 2 O photodissociation and the rotational distribution of the product (OH Ã [X 2 Å; v 0 ¼ 1]). The latter problem has played a principal role in unimolecular dissociation studies, and it has received significant experimental and theoretical attention (e.g., Carrington 1964;Yamashita 1975;Andresen et al. 1984;Häusler et al. 1987;Engel et al. 1988;Harich et al. 2000;Nizkorodov et al. 2003;Mordaunt et al. 1994;Dixon 1995;Dixon et al. 1999;van Harrevelt & van Hemert 2000). Our purpose is to augment the existing laboratory database for OH Ã rotational distributions with a set of measurements of emission from this photodissociation product of cometary H 2 O. To that end, we discuss relative g-factors, which ...

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Dynamics of the reaction O(1D2)+H2→OH(X 2Π,v″=2,3)+H: Full characterization of product energetics

Cited by 67 publications

References 38 publications

Chemistry of Atmospheric Excitation Processes

Chemistry of Atmospheric Excitation Processes

Full characterization of OH product energetics in the reaction of O(1D2) with hydrocarbons

A Comprehensive Study of Infrared OH Prompt Emission in Two Comets. II. Implications for Unimolecular Dissociation of H₂O

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Dynamics of the reaction O(1D2)+H2→OH(X 2Π,v″=2,3)+H: Full characterization of product energetics

Cited by 67 publications

References 38 publications

Chemistry of Atmospheric Excitation Processes

Chemistry of Atmospheric Excitation Processes

Full characterization of OH product energetics in the reaction of O(1D2) with hydrocarbons

A Comprehensive Study of Infrared OH Prompt Emission in Two Comets. II. Implications for Unimolecular Dissociation of H2O

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A Comprehensive Study of Infrared OH Prompt Emission in Two Comets. II. Implications for Unimolecular Dissociation of H₂O