Infrared Spectrum and Structure of Intermediates in the Reaction of OH with CO

Milligan, Dolphus E.; Jacox, Marilyn E.

doi:10.1063/1.1675022

Cited by 167 publications

(143 citation statements)

References 31 publications

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“…Previously, CO 2 +H reactions have been studied by Milligan & Jacox (1971) in UV-photolysis experiments of Ar:CO 2 :H 2 O matrices. Only the formation of more oxygen-rich species such as CO 3 has been observed, but not HCOOH.…”

Section: Discussionmentioning

confidence: 99%

“…A number of other HCOOH formation routes are possible (see e.g., Milligan & Jacox 1971;Hudson & Moore 1999;Keane 2001), from either HCO+OH → HCOOH or HCO+O → HCOO+H → HCOOH. In addition, experiments suggest that under specific catalytic conditions CO 2 can react to form HCOOH (Ogo et al 2006) but this requires catalytic surface sites, i.e., CO 2 directly attached to a silicate or metallic grain site.…”

Section: Astrophysical Implicationsmentioning

confidence: 99%

“…A large number of photolysis experiments of astrophysically relevant ices exist where H-atoms are produced through photo dissociation of H 2 O or other precursors (e.g., Ewing et al 1960;Milligan & Jacox 1964, 1971Van Ijzendoorn et al 1983;Allamandola et al 1988;Gerakines et al 2000;Moore et al 2001;Wu et al 2002). These give useful information on potential hydrogenation reactions schemes, but do not give specific information about reaction rates (see for example Sects.…”

Section: Comparison With Other Hydrogenation Experimentsmentioning

confidence: 99%

“…H-addition reactions in astrophysically relevant ices have been studied previously through UV photolysis experiments, where the hydrogen atoms are produced by dissociation of a suitable precursor molecule, often H 2 O ice (e.g., Ewing et al 1960;Milligan & Jacox 1964, 1971Van Ijzendoorn et al 1983;Allamandola et al 1988;Gerakines et al 2000;Moore et al 2001;Wu et al 2002). Although these experiments give a useful indication whether certain hydrogenation reactions may or may not occur, their results cannot be compared directly with those obtained from the laboratory studies mentioned above, nor can they be used to quantitatively test reaction schemes such as those in Fig.…”

Section: Introductionmentioning

confidence: 99%

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H-atom bombardment of CO₂, HCOOH, and CH₃CHO containing ices

Bisschop¹,

Fuchs²,

Dishoeck³

et al. 2007

A&A

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Context. Hydrogenation reactions are expected to be among the most important surface reactions on interstellar ices. However, solid state astrochemical laboratory data on reactions of H-atoms with common interstellar ice constituents are largely lacking. Aims. The goal of our laboratory work is to determine whether and how carbon dioxide (CO 2 ), formic acid (HCOOH) and acetaldehyde (CH 3 CHO) react with H-atoms in the solid state at low temperatures and to derive reaction rates and production yields. Methods. Pure CO 2 , HCOOH and CH 3 CHO interstellar ice analogues are bombarded by H-atoms in an ultra-high vacuum experiment. The experimental conditions are varied systematically. The ices are monitored by reflection absorption infrared spectroscopy and the reaction products are detected in the gas phase through temperature programmed desorption. These techniques are used to determine the resulting destruction and formation yields as well as the corresponding reaction rates. Results. Within the sensitivity of our set-up we conclude that H-atom bombardment of pure CO 2 and HCOOH ice does not result in detectable reaction products. The upper limits on the reaction rates are ≤7 × 10 −17 cm 2 s −1 which make it unlikely that these species play a major role in the formation of more complex organics in interstellar ices due to reactions with H-atoms. In contrast, CH 3 CHO does react with H-atoms. At most 20% is hydrogenated to ethanol (C 2 H 5 OH) and a second reaction route leads to the break-up of the C-C bond to form solid state CH 4 (∼20%) as well as H 2 CO and CH 3 OH (15-50%). The methane production yield is expected to be equal to the summed yield of H 2 CO and CH 3 OH and therefore CH 4 most likely evaporates partly after formation due to the high exothermicity of the reaction. The reaction rates for CH 3 CHO destruction depend on ice temperature and not on ice thickness. The results are discussed in an astrophysical context.

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Section: Discussionmentioning

confidence: 99%

Section: Astrophysical Implicationsmentioning

confidence: 99%

Section: Comparison With Other Hydrogenation Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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H-atom bombardment of CO₂, HCOOH, and CH₃CHO containing ices

Bisschop¹,

Fuchs²,

Dishoeck³

et al. 2007

A&A

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“…3 The exact height and shape of the barrier to the formation of H + CO 2 are critical to the overall kinetics of the reaction. However, beyond limited spectroscopic studies [15][16][17][18][19][20][21] and measurements of excited state dynamics, 22 little experimental information exists on the isolated HOCO radical, and there is no quantitative agreement on the nature of the barrier and the role that tunneling plays in the overall kinetics of the OH + CO reaction. 9,[23][24][25] Photoelectron-photofragment coincidence (PPC) spectroscopy 26 has been used to directly probe the HOCO PES governing the dynamics of this reaction, resolving three processes: detachment to internally excited HOCO radicals (stable channel), dissociation to H + CO 2 (exit channel), and dissociation to OH + CO (entrance channel).…”

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confidence: 99%

Communication: New insight into the barrier governing CO2 formation from OH + CO

Johnson

Poad

Shen

et al. 2011

The Journal of Chemical Physics

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Despite its relative simplicity, the role of tunneling in the reaction OH + CO → H + CO2 has eluded the quantitative predictive powers of theoretical reaction dynamics. In this study a one-dimensional effective barrier to the formation of H + CO2 from the HOCO intermediate is directly extracted from dissociative photodetachment experiments on HOCO and DOCO. Comparison of this barrier to a computed minimum-energy barrier shows that tunneling deviates significantly from the calculated minimum-energy pathway, predicting product internal energy distributions that match those found in the experiment and tunneling lifetimes short enough to contribute significantly to the overall reaction. This barrier can be of direct use in kinetic and statistical models and aid in the further refinement of the potential energy surface and reaction dynamics calculations for this system.

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